Anju bajwan
Maharshi Dayanand University, India
Title: Zirconyl chloride catalysed synthesis of 2,2'-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-ones) under green chemistry conditions
Submitted Date: Sep 09, 2016
Biography
Anju bajwan pursuing PhD in Maharshi Dayanand University, Rohtak in organic chemistry. I am working on condensation reactions and heterocyclic compounds under green chemisry conditions. I have done internship during my MSc in lupin limited for 45 days in drug quality control department. I am research oriented scholar devoting to research on green conditions.
Abstract
Nowdays main emphasis is being laid on the adoption of cleaner, safer and environmentally benign reaction conditions avoiding the use of flammable, volatile and toxic solvents for carrying out various chemical transformations. C-C bond formation via condensation of active methylene containing compounds with aromatic aldehydes is a reaction of great significance in organic synthesis. In this context the choice of aqueous medium for carrying out organic reactions consumes great significance as water plays important role in biological processes as well as a medium in organic reactions which proves to be more advantageous than those in organic solvent. Therefore, switching from organic media to aqueous media as a reaction medium is a challenging and attractive task for synthetic organic chemists. Catalyst plays a significant role in chemical industry and has a major impact on quality of human life and also its development. Among the popular reported heterogenous catalyst, Zirconyl chloride has gained the immense popularity in organic synthesis because of its recyclability, inertness, thermal stability and ease of separation from the reaction mixture.It is very attractive catalyst as it could be easily recycled via simple filtration technique. Its excellent catalytic activity can be observed over a vast array of acid catalysed organic transformations and synthesis of various organic compounds.\r\nIn course of development of green methodologies for synthesis of heterocyclic compounds having biological activity, herein we attempted for an efficient and high yielding synthesis of various substituted tetraketones i.e 2,2’-aryl-methylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) from an arylaldehyde and dimedone in 2:1 ratio in aqueous medium in the presence of zirconyl chloride. These compounds were identified on the basis of spectral analysis and by comparison with authentic samples. In the present investigation the use of any toxic and hazardous chemicals during any stage of reaction has been avoided and it meets our requirements of reaction conditions, reaction times and yields.\r\n
Richa Km
CSIR-National Chemical Laboratory, India
Title: Heterogeneous base catalyzed depolymerization of lignin into aromatic monomers
Submitted Date: Sep 09, 2016
Biography
I, Richa has completed my MSc in 2011 from Chaudhary Charan Singh University, Meerut, India and now doing my PhD since 2012 at CSIR-National Chemical Laboratory, Pune, India in Catalysis & Inorganic Chemistry Division under the guidance of Dr. Paresh L. Dhepe. My research work is focused on the replacement of soluble bases with (insoluble) heterogeneous base catalysts for the depolymerization of lignin, which would allow for easy separation of catalyst from the products and reuse. I have granted a patent for the same and manuscript is about to submitted. I also have the experience on synthesis of porous structured and amorphous materials etc.
Abstract
Lignin is generated as a major byâ€product during bio-ethanol production and is a complex three dimensional amorphous biopolymer having several aromatic rings linked together via various linkages (e.g. C-C bond, C-O-C bonds, etc.). The polyphenolic structure of lignin is ideally suitable for the catalytic transformation of it into lower molecular weight substituted phenols, which can be used as octane enhancers and platform chemicals. This research focuses on the development of heterogeneous base catalyzed method for the depolymerization of lignin (Mw~60,000 Da) at milder reaction conditions (T ≤ 300°C) to obtain the intact aromatic monomers. Various solid base catalysts were evaluated for the synthesis of aromatic monomers from depolymerization of lignin. The optimization of reaction conditions such as temperature, concentrations etc. has been done to achieve the maximum yield of aromatic monomers (~51%), by suppressing the formation of degradation products (coke, char) and gas formation. Moreover, catalyst showed a constant recycle activity minimum up to 4th run with 36 % of product yields. Various physico-chemical characterizations for both fresh and spent catalyst were described to enlighten its stability. The depolymerization of lignin yields various aromatic monomers such as vanillin, guaiacol, etc. (Scheme 1) which can be further used as platform chemicals. The yield of aromatic monomers varied strongly depending on the heterogeneous base catalyst used.
