30 Mar Alcohols and Carboxylic Acids (Esterification)
Have you been looking for JC Chemistry tuition in Singapore which will clear all our doubts and provide simplified understandings for Organic Chemistry? Organic chemistry is the branch of Chemistry that deals with the structure, properties, composition, reactions and synthesis of organic compounds that contain carbon. This subject is mandatory for JC Chemistry and has a lot of complexities in it. Students often fail to understand this chemistry topic and avoid the subject which causes the fall of their grades. At Miracle Learning Centres, our teachers are determined to provide the simplest solutions and make the tough parts easy like a breeze.
Today, we will be focusing on the topic of alcohols and carboxylic acids for our Chemistry tuition. Under alcohols and carboxylic acids, esterification is an important topic, which is the reaction between alcohols and carboxylic acids to make esters. It also looks briefly at making esters from the reactions between acryl chlorides (acid chlorides) and alcohols, and between acid anhydrides and alcohols.
The carboxylic acids form a homologous series. Like all homologous series, the carboxylic acids have the same general form, differ by CH2 in molecular formulae from neighbouring compounds, show a gradual variation in physical properties (such as their boiling and melting points) and have similar chemical properties. The functional group in the carboxylic acids is the carboxyl group, -COOH. It is responsible for the typical reactions of the carboxylic acids, which are the weak acids. For example, vinegar is a dilute solution of ethanoic acid.
A common ester, ethyl ethanoate, is formed by –CH2-CH3 and CH3-COO-. The “ethanoate” bit comes from ethanoic acid and the “ethyl” bit comes from the ethyl group on the end. The acid is named by counting up the total number of carbon atoms in the chain – including the one in the –COOH group. So, for example, CH3CH2COOH is propanoic acid, and CH3CH2COO is the propanoate group.
What are esters? Esters are derived from carboxylic acids. A carboxylic acid contains the –COOH group, and in an ester the hydrogen in this group is replaced by a hydrocarbon group of same kind. We shall just be looking at cases where it is replaced by an alkyl group, but it could equally well be an aryl group (one based on a benzene ring). To make esters, carboxylic acids react with alcohols. Esters are organic compounds which all contain the functional group, COO-. Esters have fruity smells and can be used as solvents.