Metal-Catalyzed Hydrosilylation and Defunctionalization of Carbonyl Compounds

Abstract

The Defunctionalization of carbonyl functionality into methylene by metal-catalyzed hydrosilylation is very important in organic synthesis. But very less work is done in literature because of the need for a large amount of energy for C-O bond dissociation. Metal-catalyzed defunctionalization of carbonyl compounds in the presence of silanes as a mild reducing agent is studied because of its presence as the main functionality in glucose and fructose moieties that are part of the biomass. Iron catalysis is getting attention in recent times because of its low cost, abundance, and environment-friendly nature. The use of conventional heating tools and new work-up procedure are also essential steps to implement sustainable or green chemistry protocol.

Popular Abstract

The removal of C-O group from carbonyl compounds to convert them into alkanes is very important research topic now adays because of value added products, to lower the stress of the use of renewable resources that are going to be finished in the future. The carbonyl compounds are those containing C=O functional group. The use of biomass as fuels and useful chemicals is a very sustainable approach but there are lots of functionalities in the biomass that have to remove to change it in valuable products. The biomass degradation can be enhanced using different metal catalyst. A catalyst is a chemical substance that is added in a reaction mixture to enhance the speed of a chemical reaction by lowering down bond dissociation energy required for a chemical reaction to occur. These catalysts efficiently speed up the reaction without using itself in a chemical reaction.
Various reducing agents can be used to convert C-O group into methylene. A reducing agent is chemical substance that is added in a system to remove oxygen, to add hydrogen and electron. These reducing chemicals can activate C-O functionalities that are otherwise hard to convert into alkanes. Alkanes are saturated hydrocarbons and are obtained from crude oil and are converted into beneficial compounds by various processes. Hydrocarbons are compounds containing only carbon and hydrogen.
Among various reducing agents, silanes are becoming very popular as compared to molecular hydrogen that needs high pressure conditions or NaBH4 or LiAlH4 that require very drastic conditions to reduce carbonyl compounds. Silane such as PMHS that is a by-product of a silicon industry, can be easily handled in ambient atmosphere without adopting lot of precautionary measures. The waste produced during hydrosilylation can also dispose-off very easily. Hydrosilylation is simply an addition of Si-H bond across unsaturated moieties. The organic molecules containing double or triple bonds are known as unsaturated while single bond containing compounds are placed under saturated group.
Alkanes that are obtained by these defunctionalization processes are very stable and inert at room temperature. These alkanes can be in smaller or larger units depending on the reaction conditions. Smaller units are mostly in gaseous or liquid form while bigger units are mostly solid in nature. Defunctionalization is removal of functional groups from the substrates under study.
The present work involves the reduction of carbonyl compounds into alkanes by using different metal catalysts in the presence of silanes as a reducing agent. Iron salts are very cost effective and are available in very large quantities. This project work is important in an aspect of concept of green chemistry.

• author: Zulafqar, Nazia
• supervisor: Ola Wendt
• organization: Department of Chemistry; Computational Chemistry
• course: KEMR45 20201
• year: 2020
• type: H2 - Master's Degree (Two Years)
• subject: Chemistry
• keywords: Inorganic chemistry, Catalyzed, Hydrosilylation, Defunctionalization, Carbonyl compounds, Oorganisk kemi
• language: English
• id: 9027017
• date added to LUP: 2020-09-15 11:58:59
• date last changed: 2020-09-15 11:58:59