Electrospinning of chitin nanofibers directly from an ionic liquid extract of shrimp shells

Electrospinning of chitin nanofibers directly from an ionic liquid extract of shrimp shells

 

 

Green Chem., 2013, 15,601-607
DOI: 10.1039/C2GC36582K, Communication
Patrick S. Barber, Chris S. Griggs, Jonathan R. Bonner, Robin D. Rogers
Chitin fibers were electrospun in a one-pot process directly from an ionic liquid solution of chitin extracted from dried shrimp shell, providing access to highly valuable material from a renewable waste product
High molecular weight chitin fibers were electrospun in a one-pot process directly from a 1-ethyl-3-methylimidazolium acetate solution of chitin extracted from dried shrimp shell. Such a technology obviates the need not only for the many chemicals and the energy used in industrial isolation of chitin from crustacean shells but also saves the chemicals, energy, and time needed to prepare chitin spinning dopes.
 http://pubs.rsc.org/en/Content/ArticleLanding/2013/GC/C2GC36582K?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29
Patrick S. Barber ,  Chris S. Griggs ,  Jonathan R. Bonner andRobin D. Rogers
Green Chem., 2013,15, 601-607
DOI: 10.1039/C2GC36582K
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Eco-efficient, regioselective and rapid access to 4,5-disubstituted 1,2,3-thiadiazoles via [3 + 2] cycloaddition of [small alpha]-enolicdithioesters with tosyl azide under solvent-free conditions

Eco-efficient, regioselective and rapid access to 4,5-disubstituted 1,2,3-thiadiazoles via [3 + 2] cycloaddition of [small alpha]-enolicdithioesters with tosyl azide under solvent-free conditions

 

 

 

Green Chem., 2013, Advance Article
DOI: 10.1039/C3GC37047J, Paper
Maya Shankar Singh, Anugula Nagaraju, Girijesh Kumar Verma, Gaurav Shukla, Rajiv Kumar Verma, Abhijeet Srivastava, Keshav Raghuvanshi
Regioselective synthesis of 1,2,3-thiadiazoles has been achieved via Wolff-type heteroannulation.
An efficient, sustainable, and regioselective one-pot synthesis of hitherto unreported 4-aroyl/hetaroyl/alkanoyl-5-alkyl/allyl/benzylsulfanyl-1,2,3-thiadiazoles has been achieved by [3 + 2] cycloaddition of α-enolicdithioesters with tosyl azide through cascade 1–2 (S–N) and 3–4 (C–N) bond connections involving Wolff-type heterocyclization. Optimally, the reactions are very fast and completed within 2–15 minutes, when a mixture of α-enolicdithioester and tosyl azide was stirred at 0 °C in the presence of Et3N under solvent-free conditions. Furthermore, no co-catalyst or activator is necessary. The eco-compatibility, mild conditions, excellent yields, easy purification, and avoidance of expensive/toxic reagents are advantages of this protocol to access this medicinally privileged substructure.
http://pubs.rsc.org/en/Content/ArticleLanding/2013/GC/C3GC37047J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29
Maya Shankar Singh ,  Anugula Nagaraju ,  Girijesh Kumar Verma,  Gaurav Shukla ,  Rajiv Kumar Verma ,  Abhijeet Srivastava andKeshav Raghuvanshi
Green Chem., 2013, Advance Article

DOI: 10.1039/C3GC37047J

Green chemistry, The Wittig Reaction

An example of a green Wittig Reaction

Reference:
Solvent-Free Wittig Reaction: A Green Organic Chemistry Laboratory Experiment. Sam H. Leung and Stephen A. Angel. J. Chem. Educ., 2004, 81 (10), p 1492. DOI: 10.1021/ed081p1492.

http://pubs.acs.org/doi/abs/10.1021/ed081p1492

In this experiment (E)- and (Z)-1-(4-bromophenyl)-2-phenylethene are synthesized by a solvent-free Wittig reaction. The reaction is effected by grinding the reactants in a mortar with a pestle. Both the E and Z isomers of the product are produced as evidenced by thin-layer chromatography and 1H NMR analysis. The E isomer is isolated by crystallization with ethanol in this experiment. In addition to learning about the Wittig reaction, students are also introduced to the ideas of mechanochemistry and green chemistry. This experiment can be extended to include 1H NMR analysis of the products. Students can observe the difference in the coupling constants of the alkenyl protons between the E and Z isomers of 1-(4-bromophenyl)-2-phenylethene.

The Wittig reaction or Wittig Olefination is a chemical reaction of an aldehyde or ketonewith a triphenyl phosphonium ylide (often called a Wittig reagent) to give an alkene andtriphenylphosphine oxide.[1][2]

The Wittig reaction was discovered in 1954 by Georg Wittig, for which he was awarded theNobel Prize in Chemistry in 1979. It is widely used in organic synthesis for the preparation of alkenes.[3][4][5] It should not be confused with the Wittig rearrangement.

Wittig reactions are most commonly used to couple aldehydes and ketones to singly substituted phosphine ylides. With simple ylides this results in almost exclusively the Z-alkene product. In order to obtain the E-alkene, the Schlosser modification of the Wittig reaction can be performed.

  1.  Georg WittigUlrich Schöllkopf (1954). “Über Triphenyl-phosphin-methylene als olefinbildende Reagenzien I”.Chemische Berichte 87 (9): 1318.doi:10.1002/cber.19540870919.
  2. Georg Wittig, Werner Haag (1955). “Über Triphenyl-phosphin-methylene als olefinbildende Reagenzien II”. Chemische Berichte 88 (11): 1654–1666.doi:10.1002/cber.19550881110.
  3. Maercker, A. Org. React. 196514, 270–490. (Review)
  4. W. Carruthers, Some Modern Methods of Organic Synthesis, Cambridge University Press, Cambridge, UK, 1971, pp81–90. (ISBN 0-521-31117-9)
  5. R. W. Hoffmann (2001). “Wittig and His Accomplishments: Still Relevant Beyond His 100th Birthday”. Angewandte Chemie International Edition 40 (8): 1411–1416. doi:10.1002/1521-3773(20010417)40:8<1411::AID-ANIE1411>3.0.CO;2-U.PMID 11317288.
  6. The mechanism of the Wittig reaction

mech

Wittig Reaction