Dimethyl carbonate: a versatile reagent for a sustainable valorization of renewables

Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC02118F, Critical Review
G. Fiorani, A. Perosa, M. Selva
Green upgrading of renewables via methylations and carboxymethylations with non-toxic dimethyl carbonate (DMC).

Dimethyl carbonate: a versatile reagent for a sustainable valorization of renewables

 Author affiliations

Giulia Fiorani

Postdoctoral Research Fellow presso University of Oxford
Dr. Fiorani earned her PhD in Chemical Sciences from the University of Rome “Tor Vergata” (2010) on synthesis and applications of ionic liquids. After several post-doctoral experiences (University of Padua, Italy 2010-2012, Ca’ Foscari University of Venice 2012-2013), Giulia was awarded a Marie Curie Intra-European Fellow in 2014 at ICIQ (Institute of Chemical Research of Catalonia, Tarragona, Spain) working under the supervision of Prof. Arjan W. Kleij  on the preparation of cyclic organic carbonates from CO2 and terpene based oxiranes. Giulia joined the Williams group in 2016 and is working on renewable based polymers.

Abstract

Dimethyl carbonate (DMC) is an environmentally sustainable compound which can be used efficiently for the upgrading of several promising renewables including glycerol, triglycerides, fatty acids, polysaccharides, sugar-derived platform molecules and lignin-based phenolic compounds. This review showcases a thorough overview of the main reactions where DMC acts as a methylating and/or methoxycarbonylating agent for the transformation of small bio-based molecules as well as for the synthesis of biopolymers. All processes exemplify genuine green archetypes since they couple innocuous reactants of renewable origin with non-toxic DMC. Each section of the review provides a detailed overview on reaction conditions and scope of the investigated reactions, and discusses the rationale behind the choice of catalyst(s) and the proposed mechanisms. Criticism and comments have been put forward on the pros and cons of the described methods and their perspectives, as well as on those studies which still require follow-ups and more in-depth analyses.

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Image result for Giulia Fiorani oxford

Giulia Fiorani

Ph. D. in Chemical Sciences
Post Doctoral Research Assistant
Research experience
  • Sep 2016–present
    Post Doctoral Research Assistant
    University of Oxford · Department of Chemistry · Prof. Charlotte K. Williams
    United Kingdom
    Polymer chemistry and catalysis applied to polymers preparation.
  • Mar 2016–Sep 2016
    Post Doctoral Research Assistant
    Imperial College London · Department of Materials · Prof. Charlotte K. Williams
    United Kingdom · London, England
    Polymer chemistry and catalysis applied to polymers preparation.
  • Mar 2014–Feb 2016
    Marie Curie Intra-European Fellow
    ICIQ Institute of Chemical Research of Catalonia · Prof. Arjan W. Kleij
    Spain
    Novel applications of renewable based molecules for the preparation of cyclic carbonate and polycarbonates (FP7-PEOPLE-2013-IEF, project RENOVACARB, Grant Agreement no. 622587).
  • Apr 2012–Oct 2013
    Post Doctoral Research Assistant
    Università Ca’ Foscari Venezia · Department of Molecular Science and Nanosystems · Prof. Maurizio Selva, Prof. Alvise Benedetti
    Italy
    Synthesis and characterization of luminescent Ionic Liquids.
  • Jan 2011–Feb 2012
    Post Doctoral Research Assistant
    Italian National Research Council · Institute on Membrane Technology ITM · Prof. Marcella Bonchio, Dr Alberto Figoli
    Italy · Rome
    Project BioNexGen – development of a new generation of membrane reactors.
  • Jan 2010–Dec 2010
    Research Assistant
    University of Padova · Department of Chemical Sciences · Dr Mauro Carraro
    Italy · Padova
    Hybrid nanostructures organized by hybrid ligands for the preparation of new functional materials.

Teaching experience

  • Sep 2016–Oct 2016
    Visiting Scholar
    Università degli Studi di Sassari · Department of Chemistry and Pharmacy
    Italy · Sassari
    10 hour course on terpene chemistry for PhD students.

Education

  • Nov 2006–Mar 2010
    University of Rome Tor Vergata
    Chemical Sciences · PhD
    Italy
  • Oct 2004–Jul 2006
    University of Rome Tor Vergata
    Chemistry · Master of Science
    Italy
  • Sep 2001–Oct 2004
    University of Rome Tor Vergata
    Chemistry · BSc
    Italy

Other

  • Languages

    English, Italian, Spanish

  • Scientific Societies

    Member of the Italian Chemical Society since 2007.

 

PEROSA Alvise

Qualifica Professore Associato
Telefono 041 234 8958
E-mail alvise@unive.it 
Fax 041 234 8979
Web http://www.unive.it/persone/alvise (scheda personale)
http://venus.unive.it/alvise/
Struttura Dipartimento di Scienze Molecolari e Nanosistemi
Sito web struttura: http://www.unive.it/dsmn 
Sede: Campus scientifico via Torino
Research team Environmental technology and green economy
Research team Science of complex economic, human and natural systems
Incarichi Delegato per il Dipartimento all’Internazionalizzazion

logo unive

Currently: Associate professor of Organic Chemistry with tenure.

Department of Molecular Sciences and Nanosystems, University Ca’ Foscari Venice.

 

Born in Venice in 1965. Married to Paola, two children: Alberto (2000) and Marta (2002).

 

  • Career

– 2011, was offered the senior position as Associate professor of Chemistry with Tenure at UMAss Boston.

– 2005-2014 Assistant professor of Organic Chemistry with tenure (SSD CHIM/06), University Ca’ Foscari Venice.

– 2007 Visiting scientist, University of Sydney.

– 1996-2005 Post-doctoral researcher University Ca’ Foscari Venice.

 

  • Education

– 1996 Ph.D. in Chemistry, Case Western Reserve University, Cleveland OH, USA.

– 1992 Laurea in Industrial Chemistry @ University Ca’ Foscari Venice.

 

  • Fellowships

– 2007 Endeavour Research Fellow (Austrlian Government, Department of Education, Employment and Workplace Relations) at the University of Sydney.

– 1992-1996 Fulbright Fellow (U.S. Department of State, International Educational Exchange Program) at Case Western Reserve University.

– 1993 CNR Research Fellow (1993) at Case Western Reserve University, Cleveland OH, USA.

 

  • Awards

– Ca’ Foscari Research Prize (2014, category Advanced Research).

– Royal Society of Chemistry International Journal Grants Awards (2007, 2009).

– CNR prize for research (1994).

– Outstanding teaching award CWRU (1993).

– Prize for the Laurea thesis from the Consorzio Venezia Ricerche (1992).

 

  • Editorial Board memberships

– Advisory Board of the journal “Green Chemistry” (Royal Society of Chemistry, UK).

– Editorial Advisory Board of the journal “ACS Sustainable Chemistry and Engineering” (American Chemical Society, USA).

 

  • Training and editorial activities.

– Scientific coordinator and organizer of the Summer School on Green Chemistry from 1998 to 2006 (funded by the European Commission, UNESCO, and NATO).

– Editor of the volume “Methods and Reagents for Green Chemistry” Wiley Interscience 2007.

– Editor of “Green Nanoscience”, volume 8 of the 12 volume set of the “Handbook of Green Chemistry” P. Anastas Ed., Wiley-VCH 2011.

– Author of over 60 scientific papers and chapters and of one patent in the field of organic chsmistry, with emphasis on green chemistry. Hirsch index (Scopus, Feb. 2014) = 21.

 

  • Invited talks

– Green chemistry applied to the upgrading of bio-based chemicals: towards sustainable chemical production. University of Sydney, 19 March 2014.

– Sustainable (Chemical) Solutions, Rethinking Nature in Contemporary Japan, Università Ca’ Foscari, Venezia, 25-26 February 2013

– Carbonate based ionic liquids and beyond, Green Solvents Conference, Frankfurt am Main, Dechema Gesellschaft fur Chemische Technik und Biotechnologie e. V., pp. 27, Green Solvents for Synthesis, Boppard, 8-10 Ottobre 2012

– Chemicals e Fuels da Fonti Rinnovabili, Bioforum. Biotecnologie: dove scienza e impresa si incontrano, Milano, ITER, vol. VII Edizione, Bioforum, Confindustria Venezia, 24.02.2011

– Green Chemistry for Sustainability: Teaching ionic liquids new tricks & A breath of oxygen for bio-based chemicals., Slovenian-Italian conference on Materials and Technologies for Sustainable Growth, Ajdovscina, Slovenia, 4-6 Maggio 2011

– Benign molecular design, WORKSHOP ON ECOPHARMACOVIGILANCE, Verona, 26-27 Marzo 2009

– Not merely solvents: task specific ionic liquids made by green syntheses, COIL-3 Pre-symposium workshop, Cairns, Australia, 31/05/2009

– Multiphase catalysis: a tool for green organic synthesis, Royal Australian Chemical Institute NSW Organic Chemistry Group, 28th Annual One-Day Symposium, MacQuarie University, Sydney, Australia, 5 December 2007

– Catalytic Reactions in Liquid Multiphasic Systems The acronym talk, INTAS Project on POPs, Moscow, 12-14 Giugno 2005

– Catalytic reactions in liquid multiphasic systems, Convegno: Eurogreenpol – First European Summer School on Green Chemistry of Polymers, Iasi – Rumania, 21-27 Agosto 2005

– Multiphase hydrodehalogenation reactions, RWTH Aachen – Germany, 12 Febbraio 2003

– Mechanism and Synthetic Applications of the Multiphase Catalytic Systems, International Workshop on Hazardous Halo-Aromatic Pollutants: Detoxification and Analysis, Venezia, 14-16 Maggio 2002

– The multiphase catalytic hydrodehalogenation of haloaromatics, European Summer School on Green Chemistry, Venezia, 10-15 September 2001

 

  • Academic committees

– Quality assurance board of Ca’ Foscari University

– Teaching council of the International College, Ca’ Foscari merit school.

– Academic Council of Venice International University VIU.

– Delegate for international relations of the Department of Molecular Sciences and Nanosystems.

– Scientific board of Edizioni Ca’ Foscari – Digital Publishing.

– Research committee of the Department of Molecular Sciences and Nanosystems.

– Teaching board of the Doctorate in Chemical Sciences (2012-2014).

– Teaching board of the degree course Bio- and Nanomaterials science and Technology.

– Erasmus selection committee.

– Overseas selection committee

– Post-doctoral selection committees.

 

  • Referee, reviewer, and examiner for:

– Valutazione della Qualità della Ricerca (VQR), ANVUR

– Progetti di Rilevante Interesse Nazionale (PRIN), MIUR

– American Chemical Society Petroleum Research Fund (USA).

– Ph.D. Theses, University of Nottingham (UK) and University of Sydney (Aus).

– European Science Foundation

– Journals published by: Royal Society of Chemistry, American Chemical Society, Wiley, Elsevier, Springer, IUPAC

 

  • Funded projects

– Coordinator of a Cooperlink project funded by the Italian Ministry for Education, University and Research, 2011, 12 months, entitled “Joint PhD between Università Ca’ Foscari and the University of Sydney: integration of experiment and theory towards the green synthesis of self-assemblying materials and the use of renewable resources”.

– Participant in the Project of Relevant National Interest (PRIN) “Green organic syntheses mediated by new catalytic systems”, 2010, 24 months.

– Tutor of a PhD scholarship funded by the Regione Veneto through the European Social Fund, entitled “Organic syntheses of active principles and chemicals for the pharmaceutical industry using green solvents “ 2009-2011, 36 months.

– Principal Scientist of a post-doctoral fellowship funded by the Regione Veneto through the European Social Fund entitled “New reduced environmental impact chemical synthesesfor the preparation of monomers for advanced polymers, April 2012, 12 months.

– Principal Scientist of a post-doctoral fellowship funded by the Regione Veneto through the European Social Fund entitled “Environmentally compatible chemical syntheses of fluorinated monomers for advanced materials” April 2013, 12 months.

– Principal Scientist of a post-doctoral fellowship funded by the Regione Veneto through the European Social Fund entitled “Valorisation of renewable substrates from biomass, such as glycerol and its derivatives, using green chemistry” April 2014, 12 Months

– Principal Scientist of a research contract between the chemical company Aussachem (Santandrà di Povegliano, TV), entitled: “Green Chemistry for the valorisation of glycerol and of its derivatives: new ecofriendly products” December 2013.

 

  • International collaborations and networks

– Teaching and research collaboration with the University of Sydney, School of Chemistry Laboratory for Advanced Catalysis and Sustainability prof. Thomas Maschmeyer. A joint PhD program in Chemistry was established and is currently running. Up to date 5 students (3 outgoing, 2 incoming) have benefited from this agreement The first joint PhD has been awarded in December 2013 (Marina Gottardo). Four joint publications have already been produced, and others are in preparation.

– Research collaboration with the Queen’s University of Belfast, Queen’s University Ionic Liquids Laboratory, prof. Kenneth R. Seddon, for the exchange of Erasmus students who carry out research towards their MS thesis. Currently the student Riccardo Zabeo is in Belfast w research towards his thesis, tutor dr. Perosa. Previously, the PhD student Marco Noè (tutor Perosa) spent 4 months in Belfast carrying out research that was published on an international journal.

– In the framework of a scientific collaboration with prof. Janet Scott of the Centre for Sustainable Chemical Technologies of the University of Bath, an Erasmus Mundus Joint Doctorate project entitled “Bio-Based Chemicals and Materials” was submitted in 2011 and was evaluated positively albeit not funded. Nonetheless the collaboration has already produced a joint publication.

– Summer School on Green Chemistry Network. Following the 8 editions of the “Summer school on Green Chemistry” (1998-2005) coordinated and organized by the applicant, a Green Chemistry Network was initiated that involves the following institutions: RWTH-Aachen, QUB-QUILL Belfast, UNSW-Sydney, ARKEMA-France, University of Groningen-NL, Dow Europe-CH, Universite de Poitiers, ETH-Zurich, TU-Darmstadt, Universidad Politecnica de Valencia, Delft University of Technology, TU-Munchen.

– Since 1993 Alvise Perosa is a member of the American Chemical Society.

 

  • MoU’s and International agreements

– Alvise Perosa started the Joint PhD degree in Chemistry between the University of Sydney and the Università Ca’ Foscari Venezia.

– Erasmus, Alvise Perosa is the contact person for the following Erasmus agreements: Universitat Autonoma de Barcelona, Universidad Rey Juan Carlos, Universidad Rovira i Virgili,UNIVERSITE D’AVIGNON ET DES PAYS DE VAUCLUSE, ARISTOTLE UNIVERSITY THESSALONIKI, Queen’s University of Belfast.

 

  • Academic tutoring

– Marco Noè (PhD 2009-11: 24° cycle)

– Jessica N. G. Stanley (PhD cotutelle University of Sydney, 2012-2014)

– Alessio Caretto (PhD 2012-14: 27° cycle)

– Manuela Facchin (PhD 2014-16: 29° cycle)

– Tutor if BSc and MSc level students of the degree corse in Sustainable Chemistry and Technologies and, and of the MSc degree course in Science and Technolgy of Bio- and Nanomaterials.

 

  • Teaching

– 1992-94, Case Western Reserve University, Chemistry BS: Organic Chemistry 1 Laboratory (teaching assistant award in 1993).

– 1997-2000, Università Ca’ Foscari Venezia, degree course in Environmental Sciences: Organic Chemistry Exercises.

– 1997-2000, Università Ca’ Foscari Venezia, degree course in Industrial Chemistry: Organic Chemistry 1 & 2 Laboratory, Industrial Chemistry 2 Exercises, Organic Chemistry 1 (part-time students) and Advanced Organic Chemistry.

– 2006-09, Università Ca’ Foscari Venezia, degree course in Chemical Sciences and Technologies for Cultural Heritage Conservation and Restoration: Organic Chemistry Laboratory.

– 2006-07, Università Ca’ Foscari Venezia, degree course in Chemistry, Industrial Chemistry, Materials Chemistry, Environmental Sciences: Organic Chemistry 1 and Laboratory for part-time students.

– 2005-06, 2011-12, 2012-13, 2013-14: Università Ca’ Foscari Venezia, degree course in Chemistry and in sustainable Chemical Technologies: Organic Chemistry 2 and Laboratory.

– 2011-12, Università Ca’ Foscari Venezia, degree course in Chemistry and in sustainable Chemical Technologies: Green Organic synthesis Laboratory.

– 2012-13, 2013-14 Università Ca’ Foscari Venezia, MS degree course in Bio e Nanomaterials: Colloids and Interfaces.

– 2013-14 Università Ca’ Foscari Venezia, Graduate course in Organic syntheses from renewable building blocks.

SELVA Maurizio 

Qualifica Professore Ordinario
Telefono 041 234 8687
E-mail selva@unive.it 
Fax 041 234 8979
Web http://www.unive.it/persone/selva (scheda personale)
Struttura Dipartimento di Scienze Molecolari e Nanosistemi
Sito web struttura: http://www.unive.it/dsmn 
Sede: Campus scientifico via Torino

http://www.unive.it/data/persone/5591976/pubb_tipo

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http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C7GC02118F?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

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A roadmap towards green packaging: the current status and future outlook for polyesters in the packaging industry

DOI: 10.1039/C7GC02521A, Tutorial Review
M. Rabnawaz, I. Wyman, R. Auras, S. Cheng
Approximately 99% of the plastics used in the packaging industry today are petroleum-based. However, the adoption of biobased plastics could help to greatly reduce the environmental footprint of packaging materials and help to conserve our non-renewable petroleum resources. This tutorial review provides an overview of renewable polyesters and their potential packaging materials.

A roadmap towards green packaging: the current status and future outlook for polyesters in the packaging industry

 Author affiliations

Muhammad Rabnawaz

Assistant Professor

Muhammad Rabnawaz

rabnawaz@msu.edu
Telephone: 517-432-4870


Rabnawaz’s Research Group
School of Packaging

Shouyun Cheng at Michigan State University

Shouyun Cheng

Doctor of Philosophy
Research Associate
Michigan State University
East Lansing, MI, United States

Dr. Cheng earned his PhD from South Dakota State University in May 2017. He has extensive research experiences in biomass pyrolysis and liquefaction, bio-oil catalytic cracking and hydrodeoxygenation, catalyst design, preparation, characterization and evaluation, food extruding, nano cellulose and protein peptides production, polymer synthesis, characterization and application.

Project Titles worked on: Innovation for Improved Sustainability: Scalable Approach for the Preparation of Thermoplastic Starches and their Composites for Applications in Biodegradable Packaging .

Duration in the group: August 2017- Present

Areas of Interest: Polycarbonates and polyesters synthesis, characterization and application.

MSU email Id: chengsho@msu.edu

Ian Wyman

Education: Ph.D., Queen’s University, Kingston, Ontario
M.Sc., St. Francis Xavier University, Antigonish, Nova Scotia
B.Sc. Chemistry, Dalhousie University, Halifax, Nova Scotia

Email: wymani@chem.queensu.ca

Abstract

Approximately 99% of the plastics produced today are petroleum-based, and the packaging industry alone consumes over 38% of these plastics. In this review, we argue that renewable polyesters can provide a key milestone as renewable plastics in the route toward green packaging. This review describes different classes of polyesters with particular regard to their potential use as packaging materials. Some of the families of polyesters discussed include poly(ethylene terephthalate) and its renewable analogs, poly(lactic acid), poly(hydroxyalkanoates), and poly(epoxy anhydrides). The synthesis of polyesters is discussed from a green chemistry perspective. A structure–property correlation among the various polyesters is also discussed. The challenges that currently hinder the widespread adoption of polyesters as leading packaging materials are reviewed. The environmental footprint and end of life scenario of polyesters are discussed. Finally, future research directions are summarized as a possible roadmap towards the widespread adoption of renewable polyesters as sustainable packaging materials.

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Muhammad Rabnawaz

Assistant Professor

Muhammad Rabnawaz

rabnawaz@msu.edu
Telephone: 517-432-4870

Michigan State University white graphic


Rabnawaz’s Research Group
School of Packaging


Research Interests

I have published more than 20 research articles in the field of polymer and materials sciences. Our initial endeavors can be divided into three broad categories:

  1. Polymer synthesis from renewable feedstocks.
  2. Design and preparation of smart materials.
  3. Polymer composites.

Our projects are highly applied, and we expect close collaboration with world-leading industries. These partnerships will offer unique training and career opportunities for the group members.

Experience

  • Assistant Professor, School of Packaging, Michigan State University (2016-currrent)
  • Postdoctorate, University of Illinois, Urbana-Champaign, 2015-2016
  • Postdoctorate, Queen’s University, Canada, 2013-2015

Education

  • Ph.D., Chemistry, Queen’s University, Canada, 2013
  • M.Sc., Chemistry, University of Peshawar, Pakistan, 2004

Sustainable chemistry: how to produce better and more from less?

Sustainable chemistry: how to produce better and more from less?

Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC02006F, Perspective
P. Marion, B. Bernela, A. Piccirilli, B. Estrine, N. Patouillard, J. Guilbot, F. Jerome
This review describes the rapid evolution of chemistry in the context of a sustainable development of our society. Written in collaboration between scientists from different horizons, either from public organizations or chemical companies, we aim here at providing recommendations to accelerate the emergence of eco-designed products on the market.

Sustainable chemistry: how to produce better and more from less?

 Author affiliations

Abstract

The International Symposium on Green Chemistry (ISGC) organized in 2013, 2015 and 2017 has gathered many senior and young talented scientists from all around the world (2200 attendees in three editions), either from academia or industry. Through outstanding conferences, communications, debates, and round tables, ISGC has been the witness of the rapid evolution of chemistry in the context of a sustainable development of our societies, not only at the scientific and industrial levels but also on education, networking and societal aspects. This critical review synthesizes the different points of view and the discussions having taken place at ISGC and gives a general picture of chemistry, including few scientific disciplines such as catalysis, processes, resource management, and environmental impact, among others, within the framework of sustainable development. This critical review, co-authored by researchers from public organizations and chemical companies (small, medium and large industrial groups) provides criteria and recommendations which, in our view, should be considered from the outset of research to accelerate the emergence of eco-designed products on the market.

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Conclusions

Sustainable chemistry is the only mean to generate performant  products and long lasting  solutions able  to  generate  business  and  profit  for  chemical  industry.  Performance  is  the  best  systemic answer for customer needs and our societies. Defining  sustainable  chemistry  is,  however,  far  to  be  an  easy  task  because chemistry is a highly dynamic system. The sustainability of a value chain is for instance directly depending on the access  to energy (and above all to its origin – coal, gas, biomass…) and  on the supply of raw materials. In the current economic context,  it could be not so easy to predict what will be the best source of  energy or raw materials for a desired product in the future. The  development  of  predictive  tools  is  now  essential  and  will  represent probably one of the next scientific challenges in the coming years.  During the last 20 years, utilization of renewable feedstocks in  chemical processes has become a strategy of growing interest  but  it  definitely  does  not  guarantee  the  establishment  of  a  sustainable  chemistry.  Indeed,  in  some  cases,  it  is  more  sustainable to produce a chemical from a fossil carbon source  using decarbonized energy than the reverse. It is very important  to  distinguish  the  carbon  found  in  the  final  product  from  the  carbon content corresponding to the energy which is required  the  product  production  (going  from  raw  materials  to  manufacturing,  end  of  life,  etc.).  In  this  area,  the  concept  of biorefinery can help  to secure developments and  to minimize  investments  in  production  plant  by  mutualizing  facilities  and  R&D initiatives. Cooperation with local producers can also be a valuable  way  to  implement  new  bio‐based  products  while  favouring sustainable agricultural practices.  Whatever  the  raw materials  (renewable or  fossil), a complete  and systemic life cycle analysis of the whole chain value (from resources  to  manufacturing,  use  and  end  of  life)  must  be  performed because it gives us an accurate picture of the overall  economic,  environmental  and  societal  performances  of  a  product in an application for a defined market. In general, one should never forget that sustainable chemistry should help the  society to produce more and better (products).   Emergence of sustainable innovations on the market takes a lot  of  time  because  chemists  have  to  reinvent  chemistry.  To  achieve our  transition  to a sustainable society, we must  think  differently  and  bring  together  the  worlds  of  finance,  manufacturers, researchers and public authorities. The current  method of funding of research and innovation is not satisfying  yet because  too often based on  short‐term  projects and with  high Technology Readiness Level. Governments have to realize  that  this  funding  method  slows  down,  and  sometime  also  hampers, the emergence of future sustainable innovations.   Evolution of regulations with the aim of banning toxic, eco‐toxic  or  poor  biodegradable  products  is  an  important  driver  for  sustainable innovation. It is now seen and shared as a positive sign  providing  opportunities  to  develop  systemically  better  solutions  and  allowing  chemical  companies  advocating  sustainable development and products as a must to stay in the  competition.  As  examples,  ban  of  CFC,  replacement  of  chlorinated  or  other  toxic  solvents,  substitution  of  endocrine  disruptors lead to better solutions for the global benefit of our  societies.  Improving  public  perception  and  awareness  on  sustainable  chemistry is on the way but more efforts will be needed in the  future  to  definitely  contribute  to  the  emergence  of  eco‐ designed chemicals on the market.

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Below  we  provide  a  bulleted  list  to  summarize  the  main  recommendations that are, in our views, essential for designing sustainable products.  (1) Products  design  &  Manufacture:  For  the  intended  application, sustainable chemicals must imperatively bring a  global  benefit,  created  by  a  scientific  or  technological  breakthrough,  while  minimizing  risks.  They  should  also  generate profit to emerge on the market. Products should  be  produced  according  to  the  12  principles  of  green  chemistry. In addition, their end of life should be integrated  at the outset of research,  (2) Resources: They should be available for future generations  and  should  have  low  environmental  impact  (protecting  endangered species, deforestation, erosion of biodiversity,  contamination of natural resources, global warming, etc.), it  should  make  progress  the  societal  development  of  concerned area (sharing any benefits with local producer, no  child  labour,  help  developing  countries,  etc.)  and  their  utilization  should not destabilise other  supply  chains. Non  edible raw material, a return to the idea of ‘localness’ and  the need for closeness should be preferred,  (3) Process:  The  ideal  process  would  be  a  low  Capex  or  a  progressive  Capex  process and  should  be energy‐efficient,  not  use  solvents,  be  without  effluents,  should  limit  the  number of reactional and purification steps and should be  developed  rapidly  to  limit  the  associated  risks  and  costs.  Efforts  are  still  needed  for  miniaturisation  of  equipment,  intensification and development of continuous reactors,  (4)  Energy:  The  chemical  industry  is  also  energy  intensive.  Although  less  than  10%  of  fossil  carbon  is  used  for  the  manufacture of chemicals, finding decarbonized sources of  energy  is  mandatory  to  avoid  the  depletion  of  carbon  reserves  and  price  increase  and  to  ensure  that  future  generations  will  have  access  to  the  same  resource  in  the  same amount,   (5)  Life cycle assessment: it should be assessed in all cases, the  earlier the better, by preferring a ‘cradle to grave’ approach. It should give an accurate picture of the overall economic,  environmental and societal performances of a product in an  application for a defined market,  (6)  Education:  we  should  improve  public  awareness  and  perception  on  sustainable  chemistry  to  facilitate  the  acceptation of sustainable products by the consumer. More  education  programs  should  be  launched  in  the  future  not  only to reassure the consumer but also to create a pool of  students  better  armed  to  tackle  the  future  challenges  of  (sustainable)  chemistry.  The  rapid  development  of  digital  tools should be helpful to address this issue,  (7) Network: we should prefer working in an open innovation  mode  by  bringing  together  the  worlds  of  finance,  manufacturers,  researchers  and  public  authorities  to  accelerate the emergence of eco‐designed chemicals on the  market. Networks  should enable local  players  to adapt  to  changes  in  their  environment  while  optimising  their  economic and environmental efficiency,  (8)  Funding:  A  good  balance  between  funding  to  applied  research and basic research must be addressed in order to continuously  generate  scientific  innovation.  However,  public authorities must  realise  that societal challenges are  more  important  than  the  short  term  financial  challenges  faced  by  businesses.  The  current  model  of  our  economy  based  on  rapid  profitability  is  unfortunately  not  well  adapted  for  these  advances  since  long‐term  investments  will be needed for a more sustainable development of our  society,  (9)  Legislation & Regulation: it should facilitate the emergence  of sustainable chemicals by banning harmful chemicals  for  the  human  health  and  the  environment,  even  those  nowadays  generating  substantial  profits.  The  registration  process  of  improved  sustainable  chemicals  by  the  concerned agencies should be quicker than now to speed up  their integrations on the market,  (10)  Predictive  methods:  the  development  of  tools  to  accurately  predict  the  technical  and  application  performances, the economic efficiency, the environmental  and societal performance of a  targeted product should be  developed  to  limit  the  risks  and  costs  associated  with  potential  failure  and  to  reassure  the  investors.  It  is  also  urgent  to  develop  these  tools  for  chemicals  that  are  intended to be dispersed in nature.

Increasing global access to the high-volume HIV drug nevirapine through process intensification

New Drug Approvals

Increasing global access to the high-volume HIV drug nevirapine through process intensification

Green Chem., 2017, 19,2986-2991
DOI: 10.1039/C7GC00937B, Paper
Jenson Verghese, Caleb J. Kong, Daniel Rivalti, Eric C. Yu, Rudy Krack, Jesus Alcazar, Julie B. Manley, D. Tyler McQuade, Saeed Ahmad, Katherine Belecki, B. Frank Gupton
Fundamental elements of process intensification were applied to generate efficient batch and continuous syntheses of the high-volume HIV drug nevirapine.

Green Chemistry

View original post 953 more words

Atom- and step-economical nucleophilic arylation of azaaromatics via electrochemical oxidative cross C-C coupling reactions

Atom- and step-economical nucleophilic arylation of azaaromatics via electrochemical oxidative cross C-C coupling reactions

Green Chem., 2017, 19,2931-2935
DOI: 10.1039/C7GC00789B, Communication
O. N. Chupakhin, A. V. Shchepochkin, V. N. Charushin
A simple and efficient electrochemical method for the synthesis of asymmetrical bi(het)aryls through direct functionalization of the C(sp2)-H bond in azaaromatics with fragments of (hetero)aromatic nucleophiles has been developed

From the journal:

Green Chemistry

Atom- and step-economical nucleophilic arylation of azaaromatics via electrochemical oxidative cross C–C coupling reactions

Abstract

The synthesis of asymmetrical bi(het)aryls through direct functionalization of the C(sp2)–H bond in azaaromatics with fragments of (hetero)aromatic nucleophiles has first been carried out under electrochemical oxidative conditions. This versatile method for C–C bond formation between two aryl fragments can be realized under very mild potential-controlled oxidative conditions, and it does require neither incorporation of any halogen atoms or other leaving groups, nor the use of metal catalysts. The use of the electrochemical SHN methodology for modification of azaaromatic compounds has first been demonstrated.

http://pubs.rsc.org/en/Content/ArticleLanding/2017/GC/C7GC00789B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

str5

Synthesis of compounds 3a-d

The potassium tert-butoxide (0.55 mmol), corresponding phenols 2a-d (0.55 mmol) and acetonitrile (10mL) were added to electrochemical cell under argon atmosphere. The reaction mixture was stirred at room temperature for 15 min. Then 10-methylacridinium tetrafluoroborate 1 (0.5 mmol, 140 mg) was added to the reaction mixture, and stirred at room temperature for 1 h. The supporting electrolyte (40 mL) was placed in the anode and in the cathode cell compartment (10 mL). Finally, the acetic acid (1 mmol, 57 μL) was placed in the anode cell compartment. Electrolysis was carried out at a controlled potential (reference electrode Ag/AgNO3). Upon passing 2.1F of electricity (for a two-electron process), the electrolysis was stopped, the solvent was distilled off in vacuum from the anolyte, the residue was washed with 30 ml of ether and 10 ml of water. The residue was recrystallized from water and dried on air. 9-(4-Hydroxy-3,5-dimethyl-phenyl)-10-methyl-acridinium tetrafluoroborate (3a) Orange needles. 195 mg (98%). The product was identified as a compound 3a by comparing its 1H NMR spectra with its given in the literature. Satisfactory elemental analysis for C, H and N were obtained for compound 3a; none of the experimentally found percentages deviated from the theoretical values by more than 0.3%.2

1H NMR (500 MHz, [D6]DMSO): δ 9.09 (s, 1H), 8.82 (d, 2H, J=9.2 Hz), 8.45-8.42 (m, 2H), 8.12-8.10 (m, 2H), 7.94-7.91 (m, 2H), 7.16 (s, 2H), 4.90 (s, 3H), 2.33 (s, 6H) ppm. 13C NMR (126 MHz, [D6]DMSO): δ 161.5, 155.2, 141.1, 138.2, 130.3, 130.1, 127.6, 125.7, 124.8, 123.5, 119.0, 38.8, 16.6 ppm.

str5

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Cp2TiCl: An Ideal Reagent for Green Chemistry?

 Abstract Image

The development of Green Chemistry inevitably involves the development of green reagents. In this review, we highlight that Cp2TiCl is a reagent widely used in radical and organometallic chemistry, which shows, if not all, at least some of the 12 principles summarized for Green Chemistry, such as waste minimization, catalysis, safer solvents, toxicity, energy efficiency, and atom economy. Also, this complex has proved to be an ideal reagent for green C–C and C–O bond forming reactions, green reduction, isomerization, and deoxygenation reactions of several functional organic groups as we demonstrate throughout the review.

Cp2TiCl: An Ideal Reagent for Green Chemistry?

 Department of Chemical Engineering, Escuela Politécnica Superior, University of Sevilla, 41011 Sevilla, Spain
 Organic Chemistry, ceiA3, University of Almería, 04120 Almería, Spain
§ Petrochemical Engineering, Universidad de las Fuerzas Armadas-ESPE, 050150 Latacunga, Ecuador
 Department of Organic Chemistry, Faculty of Science, University of Granada, 18071 Granada, Spain
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.7b00098
*E-mail: arosales@us.es.

http://pubs.acs.org/doi/10.1021/acs.oprd.7b00098

Synthesis and Properties of Cp2TiCl

Cp2TiCl is a single-electron-transfer (SET) complex that can be easily prepared from commercial and nontoxic Cp2TiCl2  by using economic and nontoxic reductants such as Mn or Zn. In solution, Cp2TiCl is in an equilibrium between mononuclear and dinuclear species. It has recently been reported that the stoichiometric metal reductant can be replaced by an organic reducing agent.
Figure

Although Cp2TiCl is not a renewable feedstock, it is important to say that this SET is a good alternative to them because it is obtained from nonhazardous materials and also because titanium is one of the most abundant and safe transition metals on Earth

///////////Cp2TiCl

ChemSpider 2D Image | Titanocene dichloride | C10H10Cl2Ti

Titanocene dichloride

  • Molecular FormulaC10H10Cl2Ti
  • Average mass248.959 Da
1271-19-8 [RN]
Di(2,4-cyclopentadiénide) de dichlorotitane(2+) [French] [ACD/IUPAC Name]
Dichlorotitanium(2+) di(2,4-cyclopentadienide) [ACD/IUPAC Name]
Dichlortitan(2+)di(2,4-cyclopentadienid) [German] [ACD/IUPAC Name]
Titanocene dichloride [Wiki]
Titanocene dichloride
Titanocene dichloride
Ball-and-stick model of titanocene dichloride
Sample of titanocene dichloride
Names
IUPAC name

Dichloridobis(η5-cyclopentadienyl)titanium
Other names

titanocene dichloride, dichlorobis(cyclopentadienyl)titanium(IV)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.669
PubChem CID
RTECS number XR2050000
Properties
C10H10Cl2Ti
Molar mass 248.96 g/mol
Appearance bright red solid
Density 1.60 g/cm3, solid
Melting point 289 °C (552 °F; 562 K)
sl. sol. with hydrolysis
Structure
Triclinic
Dist. tetrahedral
Hazards
R-phrases(outdated) R37R38
S-phrases(outdated) S36
NFPA 704
Flammability (red): no hazard code Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no code

NFPA 704 four-colored diamond

Related compounds
Related compounds
Ferrocene
Zirconocene dichloride
Hafnocene dichloride
Vanadocene dichloride
Niobocene dichloride
Tantalocene dichloride
Molybdocene dichloride
Tungstenocene dichloride
TiCl4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Titanocene dichloride is the organotitanium compound with the formula (η5-C5H5)2TiCl2, commonly abbreviated as Cp2TiCl2. This metallocene is a common reagent in organometallic and organic synthesis. It exists as a bright red solid that slowly hydrolyzes in air.[1]Cp2TiCl2 does not adopt the typical “sandwich” structure like ferrocene due to the 4 ligands around the metal centre, but rather takes on a distorted tetrahedral shape.[2] It shows antitumour activity and was the first non-platinum complex to undergo clinical trials as a chemotherapy drug.[3]

Preparation

The standard preparations of Cp2TiCl2 start with titanium tetrachloride. The original synthesis by Geoffrey Wilkinson and Birmingham uses sodium cyclopentadienide[4] is still commonly used:

2 NaC5H5 + TiCl4 → (C5H5)2TiCl2 + 2 NaCl

The reaction is conducted in THF. Workup sometimes washing with hydrochloric acid to convert hydrolysis derivatives to the dichloride. Recrystallization from toluene forms acicular crystals.

Cp2TiCl2 can also be prepared by using freshly distilled cyclopentadiene rather than its sodium derivative:

2 C5H6 + TiCl4 → (C5H5)2TiCl2 + 2 HCl

This reaction is conducted under a nitrogen atmosphere and by using THF as solvent. The product is purified by soxhlet extractionusing toluene as solvent.[5]

The complex is pseudotetrahedral. Each of the two Cp rings are attached as η5 ligands.

Applications in organic synthesis

Cp2TiCl2 is a generally useful reagent that effectively behaves as a source of Cp2Ti2+. A large range of nucleophiles will displace chloride. Examples:

Application in preparing sulfur allotropes[edit]

Titanocene dichloride is used to prepare titanocene pentasulfide, a precursor to unusual alloptropes of sulfur:

Li2S5 + (C5H5)2TiCl2 → (C5H5)2TiS5 + LiCl

Structure of pentasulfur-The resulting pentasulfur-titanocene complex is allowed to react with polysulfur dichloride to give the desired cyclosulfur of in the series:[10]

Reactions

Cp2TiCl2 undergoes anion exchange reactions, e.g. to give the pseudohalides. With NaSH and with polysulfide salts, one obtains the sulfido derivatives Cp2Ti(SH)2 and Cp2TiS5.

One Cp ligand can be removed from Cp2TiCl2 to give tetrahedral CpTiCl3. This conversion can be effected with TiCl4 or by reaction with SOCl2.[11]

Reduction with zinc gives the dimer of bis(cyclopentadienyl)titanium(III) chloride in a solvent-mediated chemical equilibrium:[12][13]

N-RB equilibrium.jpg

Ti(II) derivatives

Cp2TiCl2 is a precursor to many TiII derivatives, though titanoce itself, TiCp2, is so highly reactive that it rearranges into a TiIII hydride dimer and has been the subject of much investigation.[14][15] This dimer can be trapped by conducting the reduction of titanocene dichloride in the presence of ligands; in the presence of benzene, a fulvalene complex, μ(η55-fulvalene)-di-(μ-hydrido)-bis(η5-cyclopentadienyltitanium), can be prepared and the resulting solvate structurally characterised by X-ray crystallography.[16] The same compound had been reported earlier by a lithium aluminium hydride reduction[17] and sodium amalgam reduction[18] of titanocene dichloride, and studied by 1H NMR[19] prior to its definitive characterisation.[14][15]

“Titanocene” is not Ti(C5H5)2, but rather this isomer with a fulvalene dihydride structure.[15][16]

Reductions have been investigated using Grignard reagent and alkyl lithium compounds. More conveniently handled reductants include Mg, Al, or Zn. The following syntheses demonstrate some of the compounds that can be generated by reduction of titanocene dichloride in the presence of π acceptor ligands:[20]

Cp2TiCl2 + 2 CO + Mg → Cp2Ti(CO)2 + MgCl2
Cp2TiCl2 + 2 PR3 + Mg → Cp2Ti(PR3)2 + MgCl2
Cp2TiCl2 + 2 Me3SiCCSiMe3 + Mg → Cp2TiMe3SiCCSiMe3 + MgCl2

With only one equivalent of reducing agent, TiIII species such as Cp2TiCl result.

Alkyne and benzyne derivatives of titanocene are well known.[21] One family of derivatives are the titanocyclopentadienes.[22]

Titanocene equivalents react with alkenyl alkynes followed by carbonylation and hydrolysis to form bicyclic cyclopentadienones, related to the Pauson–Khand reaction).[23] A similar reaction is the reductive cyclization of enones to form the corresponding alcohol in a stereoselective manner.[24]

Reduction of titanocene dichloride in the presence of conjugated dienes such as 1,3-butadiene gives η3-allyltitanium complexes.[25] Related reactions occur with diynes. Furthermore, titanocene can catalyze C-C bond metathesis to form asymmetric diynes.[22]

Derivatives of (C5Me5)2TiCl2

Many analogues of Cp2TiCl2 are known. Prominent examples are the ring-methylated derivatives (C5H4Me)2TiCl2 and (C5Me5)2TiCl2. The ethylene complex (C5Me5)2Ti(C2H4) can be synthesised by Na reduction of (C5Me5)2TiCl2 in the presence of ethylene. The Cp compound has not been prepared. This pentamethylcyclopentadienyl (Cp*) species undergoes many reactions such as cycloadditions of alkynes.[21]

Medicinal research

Titanocene dichloride was investigated as an anticancer drug.[26] In fact, it was both the first non-platinum coordination complex and the first metallocene to undergo a clinical trial.[3]The mechanism by which it acts is not fully understood; however, it has been conjectured that its activity might be attributable to the compound’s interactions with the protein transferrin.[3][27]

References

  1. Jump up^ Budaver, S., ed. (1989). The Merck Index (11th ed.). Merck & Co., Inc.
  2. Jump up^ Clearfield, Abraham; Warner, David Keith; Saldarriaga Molina, Carlos Hermán; Ropal, Ramanathan; Bernal, Ivan; et al. (1975). “Structural Studies of (π-C5H5)2 MX2 Complexes and their Derivatives. The Structure of Bis(π-cyclopentadienyl)titanium Dichloride”. Can. J. Chem53 (11): 1621–1629. doi:10.1139/v75-228.
  3. Jump up to:a b c Roat-Malone, R. M. (2007). Bioinorganic Chemistry: A Short Course (2nd ed.). John Wiley & Sons. pp. 19–20. ISBN 978-0-471-76113-6.
  4. Jump up^ Wilkinson, G.; Birmingham, J.G. (1954). “Bis-cyclopentadienyl Compounds of Ti, Zr, V, Nb and Ta”. J. Am. Chem. Soc. 76 (17): 4281–4284. doi:10.1021/ja01646a008.
  5. Jump up^ Birmingham, J. M. (1965). “Synthesis of Cyclopentadienyl Metal Compounds”. Adv. Organometal. Chem. 2: 365–413. doi:10.1016/S0065-3055(08)60082-9.
  6. Jump up^ Payack, J. F.; Hughes, D. L.; Cai, D.; Cottrell, I. F.; Verhoeven, T. R. (2002). “Dimethyltitanocene”Org. Synth. 79: 19.
  7. Jump up^ Claus, K.; Bestian, H. (1962). “Über die Einwirkung von Wasserstoff auf einige metallorganische Verbindungen und Komplexe”. Justus Liebigs Ann. Chem. 654: 8. doi:10.1002/jlac.19626540103.
  8. Jump up^ Herrmann, W.A. (1982). “The Methylene Bridge”. Adv. Organomet. Chem20: 159–263. doi:10.1016/s0065-3055(08)60522-5.
  9. Jump up^ Straus, D. A. (2000). “μ-Chlorobis(cyclopentadienyl)(dimethylaluminium)-μ-methylenetitanium”. Encyclopedia of Reagents for Organic Synthesis. London: John Wiley.
  10. Jump up^ Housecroft, Catherine E.; Sharpe, Alan G. (2008). “Chapter 16: The group 16 elements”. Inorganic Chemistry (3rd ed.). Pearson. p. 498. ISBN 978-0-13-175553-6.
  11. Jump up^ Chandra, K.; Sharma, R. K.; Kumar, N.; Garg, B. S. (1980). “Preparation of η5-Cyclopentadienyltitanium Trichloride and η5-Methylcyclopentadienyltitanium Trichloride”. Chem. Ind. – London44: 288–289.
  12. Jump up^ Manzer, L. E.; Mintz, E. A.; Marks, T. J. (1982). “Cyclopentadienyl Complexes of Titanium(III) and Vanadium(III)”. Inorg. Synth. 21: 84–86. doi:10.1002/9780470132524.ch18.
  13. Jump up^ Nugent, William A.; RajanBabu, T. V. “Transition-metal-centered radicals in organic synthesis. Titanium(III)-induced cyclization of epoxy olefins”. J. Am. Chem. Soc. 110 (25): 8561–8562. doi:10.1021/ja00233a051.
  14. Jump up to:a b Wailes, P. C.; Coutts, R. S. P.; Weigold, H. (1974). “Titanocene”. Organometallic Chemistry of Titanium, Zirconium, and Hafnium. Organometallic Chemistry. Academic Press. pp. 229–237. ISBN 9780323156479.
  15. Jump up to:a b c Mehrotra, R. C.; Singh, A. (2000). “4.3.6 η5-Cyclopentadienyl d-Block Metal Complexes”. Organometallic Chemistry: A Unified Approach (2nd ed.). New Delhi: New Age International Publishers. pp. 243–268. ISBN 9788122412581.
  16. Jump up to:a b Troyanov, Sergei I.; Antropiusová, Helena; Mach, Karel (1992). “Direct proof of the molecular structure of dimeric titanocene; The X-ray structure of μ(η55-fulvalene)-di-(μ-hydrido)-bis(η5-cyclopentadienyltitanium)·1.5 benzene”. J. Organomet. Chem. 427 (1): 49–55. doi:10.1016/0022-328X(92)83204-U.
  17. Jump up^  Antropiusová, Helena;  Dosedlová, Alena;  Hanuš, Vladimir; Karel,  Mach (1981). “Preparation of μ-(η55-Fulvalene)-di-μ-hydrido-bis(η5-cyclopentadienyltitanium) by the reduction of Cp2TiCl2 with LiAlH4 in aromatic solvents”. Transition Met. Chem. 6 (2): 90–93. doi:10.1007/BF00626113.
  18. Jump up^ Cuenca, Tomas; Herrmann, Wolfgang A.; Ashworth, Terence V. (1986). “Chemistry of oxophilic transition metals. 2. Novel derivatives of titanocene and zirconocene”. Organometallics5 (12): 2514–2517. doi:10.1021/om00143a019.
  19. Jump up^ Lemenovskii, D. A.; Urazowski, I. F.; Grishin, Yu K.; Roznyatovsky, V. A. (1985). “1H NMR Spectra and electronic structure of binuclear niobocene and titanocene containing fulvalene ligands”. J. Organomet. Chem. 290 (3): 301–305. doi:10.1016/0022-328X(85)87293-4.
  20. Jump up^ Kuester, Erik (2002). “Bis(5-2,4-cyclopentadienyl)bis(trimethylphosphine)titanium”. Encyclopedia of Reagents for Organic Synthesis. John Wiley. doi:10.1002/047084289X.rn00022.
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Further reading

IR of Titanocene dichloride

MS of Titanocene dichloride

HNMR of Titanocene dichloride

ESR of Titanocene dichloride

ESR

MORE……………

Introduction

Natural product synthesis is an exigent test for newly developed methodologies. Within this context, Rajanbabu and Nugent reported a series of seminal papers about the potential role of Cp2TiCl as a new tool in organic synthesis.1 Soon afterwards, Gansäuer’s group published a collection of relevant papers where a substoichiometric version of this protocol was developed.2Those results were especially important in the development of the corresponding asymmetric reactions using chiral titanocene(III) complexes.3 After these inspiring works, titanocene(III) complexes, essentially titanocene(III) chloride (Cp2TiCl), have recently emerged as a powerful tool in organic synthesis. They are soft single-electron-transfer (SET) reagents capable of promoting different kinds of reactions, such as homolytic epoxide4 and oxetane5 openings, Barbier-type reactions,6 Wurtz-type reactions,7 Reformatsky-type reactions,8 reduction reactions,9 and pinacol coupling reactions (Scheme 1).10

image file: c3qo00024a-s1.tif
Scheme 1 General reactivity of Cp2TiCl.

Image result for Titanocene chloride

From a practical point of view, titanocene(III) complexes can be prepared and stored. Nevertheless, they are usually highly oxygen-sensitive compounds. Interestingly, they can be easily prepared in situ by simply stirring the corresponding titanocene(IV) precursor and manganese or zinc dust. Another key characteristic of the titanocene(III) chemistry is that whatever the reaction in which it is involved, a catalytic cycle can be closed. In that case, a titanocene(IV) regenerating agent and an electron source, such as manganese or zinc dust, are required. Although some of them have been described in the literature, only two are commonly used: the simple combination of trimethylsilyl chloride and 2,4,6-collidine for aprotic reaction conditions11 and 2,4,6-collidinium hydrochloride for aqueous conditions (see Scheme 2).2

image file: c3qo00024a-s2.tif
Scheme 2 Catalytic cycles in titanocene(III) chemistry.

http://pubs.rsc.org/en/Content/ArticleHtml/2014/QO/c3qo00024a

Conclusions

Titanocene(III)-mediated radical processes have been applied to the synthesis of natural products of diverse nature. Beyond simple functional group interconversions, radical cyclizations, mainly from epoxides, have demonstrated their utility to yield (poly)cyclic natural skeletons, which are valuable synthons in organic synthesis. This radical approach has in many cases resulted in better yields and stereoselectivities than the cationic equivalents. In particular, the synthesis at room temperature of stereodefined terpenic skeletons without enzymatic assistance is remarkable. In this context, the main limitation of this bioinspired approach is, in fact, its extraordinary stereoselectivity, which avoids obtaining cis-fused decalins and/or substituents in axial positions. Such stereochemistry is present in many interesting natural terpenes. On the other hand, as can be seen in the first part of the review, the diverse reactivity of titanocene(III) complexes derives in some functional group incompatibilities. It is expected that in near future judicious designs of new titanocene(III) complexes can resolve this drawback. In any case, the evolution of the applications of titanocene(III) in natural product synthesis suggests that these reagents can be a matter of choice in the arsenal of a synthetic organic chemist.

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Green Synthesis of Veratraldehyde Using Potassium Promoted Lanthanum–Magnesium Mixed Oxide Catalyst

 Abstract Image

Veratraldehyde is an important chemical used in perfumery, agrochemical, and pharmaceutical industries. Current processes of manufacture of veratraldehyde use homogeneous catalysts, which make them highly polluting, creating problems of disposal of effluents and product purity. In the current work, veratraldehyde was synthesized from O-alkylation of vanillin with an environmentally benign reagent, dimethyl carbonate. A series of potassium loaded La2O3–MgO were prepared by the incipient wetness impregnation method, and their performance was evaluated vis-à-vis MgO, La2O3, La2O3–MgO, and a series of 1–4 wt % K/La2O3–MgO. All catalysts were characterized by different techniques, such as N2 adsorption/desorption, XRD, TGA-DSC, FT-IR, CO2-TPD, and SEM techniques. The effect of different loadings (1–4 wt %) of potassium on La2O3–MgO was studied, among which 2 wt % K/La2O3–MgO showed the best activity and selectivity due to high dispersion of potassium and high basicity in comparison with the rest. The activity of 2 wt % K/La2O3–MgO in O-methylation of vanillin with dimethyl carbonate (DMC) was closely associated with basicity. Various parameters were studied to achieve the maximum yield of the desired product. The maximum conversion was found with catalyst loading of 0.03 g/cm3 and mole ratio of vanillin and DMC of 1:15 at 160 °C in 2 h. The reaction follows pseudo-first-order kinetics for the O-methylation of vanillin. The energy of activation was found to be 13.5 kcal/mol. Scale-up was done using the kinetic model to observe that the process could be scaled up using the process parameters. The overall process is clean and green.

Figure

Green Synthesis of Veratraldehyde Using Potassium Promoted Lanthanum–Magnesium Mixed Oxide Catalyst

Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga Mumbai-400 019, India
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.7b00127
*E-mail: gd.yadav@ictmumbai.edu.in, Phone: +91-22-3361-1001, Fax: +91-22-3361-1020; +91-22-3361-1002.

Conclusion


Synthesis of veratraldehyde using a catalytic green process is desirable in today’s environmentally conscious world. Therefore, a new process was devised in this work using a novel catalyst using mixed metal oxides. Different loadings of potassium promoted on La2O3–MgO (1–4 wt %) catalysts were synthesized and characterized by various techniques. The activity of catalyst was studied in the reaction of vanillin with DMC for the synthesis of veratraldehyde in comparison with several other catalysts, such as MgO, La2O3, La2O3–MgO, 1 wt % K/La2O3–MgO, 2 wt % K/La2O3–MgO, 3 wt % K/La2O3–MgO, and 4 wt % K/La2O3–MgO. Potassium promoted mixed oxides showed much higher catalytic activity than the corresponding pure La2O3–MgO mixed oxide, due to an increase in moderate, strong, superbasic sites. Moreover, loading of potassium on La2O3–MgO changes the structural properties, such as pore volume and surface area, and it gives higher conversion toward the desired product. Two wt % K/La2O3–MgO is the best and gives 96% of conversion at mole ratio 1:15 of vanillin to DMC and 0.03 g/cm3 catalyst loading at 160 °C. By using this catalyst, we studied various parameters systematically to establish kinetics. The catalyst is reusable up to four cycles. The energy of activation for O-methylation of vanillin was found to be 13.5 kcal/mol. A scale up was also attempted. Experimental and theoretical values matched very well. The process is green and clean.
Jayaram Molleti
Institute Of Chemical Technology
Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga Mumbai-400 019, India
Image result
Prof. GD Yadav, Vice-Chancellor, ICT, Mumbai
*E-mail: gd.yadav@ictmumbai.edu.in, Phone: +91-22-3361-1001, Fax: +91-22-3361-1020; +91-22-3361-1002.
Institute Of Chemical Technology
Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga Mumbai-400 019, India