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.


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.

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


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
IUPAC name

Other names

titanocene dichloride, dichlorobis(cyclopentadienyl)titanium(IV)
3D model (JSmol)
ECHA InfoCard 100.013.669
PubChem CID
RTECS number XR2050000
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
Dist. tetrahedral
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
Zirconocene dichloride
Hafnocene dichloride
Vanadocene dichloride
Niobocene dichloride
Tantalocene dichloride
Molybdocene dichloride
Tungstenocene dichloride
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]


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]


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]


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  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.
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  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.
  21. Jump up to:a b Buchwald, S.L.; Nielsen, R.B. (1988). “Group 4 Metal Complexes of Benzynes, Cycloalkynes, Acyclic Alkynes, and Alkenes”. Chem. Rev. 88 (7): 1047–1058. doi:10.1021/cr00089a004.
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  23. Jump up^ Hicks, F. A.; et al. (1999). “Scope of the Intramolecular Titanocene-Catalyzed Pauson-Khand Type Reaction”. J. Am. Chem. Soc. 121 (25): 5881–5898. doi:10.1021/ja990682u.
  24. Jump up^ Kablaoui, N. M.; Buchwald, S. L. (1998). “Development of a Method for the Reductive Cyclization of Enones by a Titanium Catalyst”. J. Am. Chem. Soc. 118 (13): 3182–3191. doi:10.1021/ja954192n.
  25. Jump up^ Sato, F.; Urabe, Hirokazu; Okamoto, Sentaro (2000). “Synthesis of Organotitanium Complexes from Alkenes and Alkynes and Their Synthetic Applications”. Chem. Rev. 100(8): 2835–2886. PMID 11749307doi:10.1021/cr990277l.
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Further reading

IR of Titanocene dichloride

MS of Titanocene dichloride

HNMR of Titanocene dichloride

ESR of Titanocene dichloride




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.



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.




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.


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.


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

Is water a suitable solvent for the catalytic amination of alcohols?

Is water a suitable solvent for the catalytic amination of alcohols?

Green Chem., 2017, 19,2839-2845
DOI: 10.1039/C7GC00422B, Paper
Johannes Niemeier, Rebecca V. Engel, Marcus Rose
The catalytic aqueous-phase amination of biogenic alcohols with solid catalysts is reported for future development of renewable amine value-added chains.

Green Chemistry

Is water a suitable solvent for the catalytic amination of alcohols?


The catalytic conversion of biomass and biogenic platform chemicals typically requires the use of solvents. Water is present already in the raw materials and in most cases a suitable solvent for the typically highly polar substrates. Hence, the development of novel catalytic routes for further processing would profit from the optimization of the reaction conditions in the aqueous phase mainly for energetic reasons by avoiding the initial water separation. Herein, we report the amination of biogenic alcohols in aqueous solutions using solid Ru-based catalysts and ammonia as a reactant. The influence of different support materials and bimetallic catalysts is investigated for the amination of isomannide as a biogenic diol. Most importantly, the transferability of the reaction conditions to various other primary and secondary alcohols is successfully proved. Hence, water appears to be a suitable solvent for the sustainable production of biogenic amines and offers great potential for further process development.


Selective hydrogenation of N-heterocyclic compounds using Ru nanocatalysts in ionic liquids

Selective hydrogenation of N-heterocyclic compounds using Ru nanocatalysts in ionic liquids

Green Chem., 2017, 19,2762-2767
DOI: 10.1039/C7GC00513J, Communication
Hannelore Konnerth, Martin H. G. Prechtl
N-Heterocyclic compounds have been tested in the selective hydrogenation catalysed by small 1-3 nm sized Ru nanoparticles (NPs) embedded in various imidazolium based ionic liquids (ILs).


From the journal:

Green Chemistry

Selective hydrogenation of N-heterocyclic compounds using Ru nanocatalysts in ionic liquids


N-Heterocyclic compounds have been tested in the selective hydrogenation catalysed by small 1–3 nm sized Ru nanoparticles (NPs) embedded in various imidazolium based ionic liquids (ILs). Particularly a diol-functionalised IL shows the best performance in the hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline (1THQ) with up to 99% selectivity.


Selective synthesis of dimethoxyethane via directly catalytic etherification of crude ethylene glycol

Selective synthesis of dimethoxyethane via directly catalytic etherification of crude ethylene glycol

Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC00659D, Paper
Weiqiang Yu, Fang Lu, Qianqian Huang, Rui Lu, Shuai Chen, Jie Xu
A potential diesel fuel additive, dimethoxyethane, was highly selectively produced via etherification of crude ethylene glycol over SAPO-34

From the journal:

Green Chemistry

Selective synthesis of dimethoxyethane via directly catalytic etherification of crude ethylene glycol


Etherification of ethylene glycol with methanol provides a sustainable route for the production of widely used dimethoxyethane; dimethoxyethane is a green solvent and reagent that is applied in batteries and used as a potential diesel fuel additive. SAPO-34 zeolite was found to be an efficient and highly selective catalyst for this etherification via a continuous flow experiment. It achieved up to 79.4% selectivity for dimethoxyethane with around 96.7% of conversion. The relationship of the catalyst’s structure and the dimethoxyethane selectivity was established via control experiments. The results indicated that the pore structure of SAPO-34 effectively limited the formation of 1,4-dioxane from activated ethylene glycol, enhanced the reaction of the activated methanol with ethylene glycol in priority, and thus resulted in high selectivity for the desired products. The continuous flow technology used in the study could efficiently promote the complete etherification of EG with methanol to maintain high selectivity for dimethoxyethane.


Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source

Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source

Green Chem., 2017, Advance Article
DOI: 10.1039/C7GC01289F, Paper
Zhanhui Yang, Zhongpeng Zhu, Renshi Luo, Xiang Qiu, Ji-tian Liu, Jing-Kui Yang, Weiping Tang
A highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water, using formic acid as a reductant.

Green Chemistry

Iridium-catalyzed highly efficient chemoselective reduction of aldehydes in water using formic acid as the hydrogen source


A water-soluble highly efficient iridium catalyst is developed for the chemoselective reduction of aldehydes to alcohols in water. The reduction uses formic acid as the traceless reducing agent and water as a solvent. It can be carried out in air without the need for inert atmosphere protection. The products can be purified by simple extraction without any column chromatography. The catalyst loading can be as low as 0.005 mol% and the turn-over frequency (TOF) is as high as 73 800 mol mol−1 h−1. A wide variety of functional groups, such as electron-rich or deficient (hetero)arenes and alkenes, alkyloxy groups, halogens, phenols, ketones, esters, carboxylic acids, cyano, and nitro groups, are all well tolerated, indicating excellent chemoselectivity.


Image result for 4-Methoxybenzyl alcohol

4-Methoxybenzyl alcohol (2a)2 . Yellowish oil. Yield: 273 mg, 99%.

1H NMR (400 MHz, CDCl3) δ 7.23 (d, J = 8.8 Hz, 2H), 6.85 (d, J = 8.7 Hz, 2H), 4.52 (s, 2H), 3.76 (s, 3H).

13C NMR (101 MHz, CDCl3) δ 159.07, 133.23, 128.63, 113.89, 64.73, 55.30, 55.26.

Zhanhui Yang

Zhanhui Yang

School of Pharmacy, University of Wisconsin–Madison, Madison, USA

Organic Chemistry, Green Chemistry, Catalysis

PhD student
Beijing University of Chemical Technology
Organic Chemistry
Beijing, China
Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA
School of Pharmacy, University of Wisconsin–Madison, Madison, USA
Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA

Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA

Image result for School of Pharmacy, University of Wisconsin–Madison, Madison, USA

4-Methoxybenzyl alcohol


Continuous niobium phosphate catalysed Skraup reaction for quinoline synthesis from solketal



Continuous niobium phosphate catalysed Skraup reaction for quinoline synthesis from solketal
Green Chem., 2017, Advance Article
DOI: 10.1039/C6GC03140D, Paper
Jing Jin, Sandro Guidi, Zahra Abada, Zacharias Amara, Maurizio Selva, Michael W. George, Martyn Poliakoff
Solketal is derived from the reaction of acetone with glycerol, a by-product of the biodiesel industry. We demonstrate the use of NbOPO4 as a catalyst for the conversion of solketal and anilines to quinolines






Synthesis of 4-(quinolin-6-yl methyl)aniline (6a)

The reaction was carried out accordingly to the general procedure. The purification of 4-(quinoline-6-yl methyl)aniline 6a was carried out with a gradient of polarity from 80:20 to 30:70 (v/v) of CyHex:AcOEt as eluent. 1H NMR (400 MHz, CDCl3) δ ppm: 8.85 (dd, J=4.3,1.7Hz, 1H), 8.07 (dd, J=8.3,1.8Hz, 1H), 8.01 (d, J=9.2Hz, 1H), 7.58–7.54 (m, 2H), 7.36 (dd, J=8.3,4.2Hz, 1H), 7.02 (d, J=8.3Hz, 2H), 6.67–6.63 (m, 2H), 4.06 (s, 2H). 13C NMR (100 MHz, CDCl3) δ ppm: 149.9, 147.3, 144.9, 140.7, 135.9, 131.4, 130.6, 130.1, 129.5, 128.5, 126.6, 121.2, 115.5, 41.2. HRMS-ESI for C16H15N2 [M+H]+ calculated 235.1235, found 235.1245.

Continuous niobium phosphate catalysed Skraup reaction for quinoline synthesis from solketal

Author affiliations


Solketal is derived from the reaction of acetone with glycerol, a by-product of the biodiesel industry. We report here the continuous reaction of solketal with anilines over a solid acid niobium phosphate (NbP), for the continuous generation of quinolines in the well-established Skraup reaction. This study shows that NbP can catalyse all the stages of this multistep reaction at 250 °C and 10 MPa pressure, with a selectivity for quinoline of up to 60%. We found that the catalyst eventually deactivates, most probably via a combination of coking and reduction processes but nevertheless we show the promise of this approach. We demonstrate here the application of our approach to synthesize both mono- and bis-quinolines from the commodity chemical, 4,4′-methylenedianiline.