What does a catalyst contribute to the transesterification process?
Transesterification is one of the reversible reactions and proceeds essentially by mixing the reactants. However, the presence of a catalyst (a strong acid or base) accelerates the conversion and a little excess of alcohol is used to shift the equilibrium toward the formation of fatty acid alkyl esters and glycerol.
What is the first step in base catalyzed transesterification?
The mechanism of the base-catalyzed transesterification of vegetable oils is shown in Scheme 6. The first step (Eq. 1) is the reaction of the base with the alcohol, producing an alkoxide and the protonated catalyst. Alkaline metal hydroxides (KOH and NaOH) are cheaper than metal alkoxides, but less active.
Why methanol acid and ethanol are used most frequently for the transesterification?
In this reaction, methanol and ethanol are the most commonly used alcohols because of their low cost and availability. This reaction has been widely used to reduce the viscosity of nonedible oil and for the conversion of triglycerides into ester.
What is esterification process?
Esterification is a chemical reaction that forms at least one ester (= a type of compound produced by reaction between acids and alcohols). Esters are produced when acids are heated with alcohols in a process called esterification. An ester can be made by an esterification reaction of a carboxylic acid and an alcohol.
What is esterification and example?
Some esters can be prepared by esterification, a reaction in which a carboxylic acid and an alcohol, heated in the presence of a mineral acid catalyst, form an ester and water: The reaction is reversible. As a specific example of an esterification reaction, butyl acetate can be made from acetic acid and 1-butanol.
What happens during esterification?
Esterification occurs when a carboxylic acid reacts with an alcohol. This reaction lost an -OH from the carboxylic acid and a hydrogen from the alcohol. These two also combine to form water. So any esterification reaction will also form water as a side product.
When to use alcohol as a catalyst for transesterification?
When in ester is placed in a large excess of an alcohol along with presence of either an acid or a base there can be an exchange of alkoxy groups. The large excess of alcohol is used to drive the reaction forward. The most common method of transesterification is the reaction of the ester with an alcohol in the presence of an acid catalyst eg:
Where does the catalytic reaction take place in transesterification?
In the last step the rearrangement of the tetrahedral intermediate gives rise to an ester and a diglyceride. When the transesterification reaction occurred in the presence of the solid base catalyst such as BaO, SrO, CaO, and MgO, the catalytic reactions take place on the surface of solid base catalysts.
How does the transesterification of an ester work?
In the transesterification mechanism, the carbonyl carbon of the starting ester react to give a tetrahedral intermediate, which either reverts to the starting material, or proceeds to the transesterified product (RCOOR 2).
What is the mechanism of transesterification in acidic conditions?
Mechanism in acidic conditions. Contributors. Transesterification is the conversion of a carboxylic acid ester into a different carboxylic acid ester.