|
Transesterification
In organic chemistry, transesterification is the process of exchanging the organic group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. The reaction can also be accomplished with the help of other enzymes, particularly lipases (one example is the lipase E.C.3.1.1.3). Strong acids catalyse the reaction by donating a proton to the carbonyl group, thus making it a more potent electrophile, whereas bases catalyse the reaction by removing a proton from the alcohol, thus making it more nucleophilic. If the alcohol produced by the reaction can be separated from the reactants by distillation this will drive the equilibrium toward the products, this means that esters with larger alkoxy groups can be made from methyl or ethyl esters in high purity by heating the mixture of ester, acid/base, and large alcohol. Mechanism In the transesterification mechanism, the carbonyl carbon of the starting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biodiesel
Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat ( tallow), soybean oil, or some other vegetable oil with an alcohol, producing a methyl, ethyl or propyl ester by the process of transesterification. Unlike the vegetable and waste oils used to fuel converted diesel engines, biodiesel is a drop-in biofuel, meaning it is compatible with existing diesel engines and distribution infrastructure. However, it is usually blended with petrodiesel (typically to less than 10%) since most engines cannot run on pure Biodiesel without modification. Biodiesel blends can also be used as heating oil. The US National Biodiesel Board defines "biodiesel" as a mono-alkyl ester. Blends Blends of biodiesel and conventional hydrocarbon-based diesel are most commonly distributed for use in the retail diesel fuel marketplace. Much of the world uses a syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
