Short chain fatty acids Define a fatty acid in terms of chem

Short chain fatty acids Define a fatty acid, in terms of chemical structure. Draw the structures of the short chain (volatile) fatty acids with: 2 carbons (acetic acid) 3 carbons (propionic acid) 4 carbons (butyric acid) Since each of the above is an acid, it readily loses a proton. For example, acetic acid loses a proton to form acetate, and acetic acid is called an acid-base pair. Write the structures of the base for acetic acid (acetate)

Solution

3.

Answer (A)

Fatty acids are carbon chains with a methyl group at one end of the molecule (designated omega, ) and a carboxyl group at the other end. The carbon atom next to the carboxyl group is called the carbon, and the subsequent one the carbon. The letter n is also often used instead of the Greek to indicate the position of the double bond closest to the methyl end.

CH3 – (CH2 )n– CH2 – CH2 – COOH

Answer (B) Structure of short chain (volatile) fatty acids

(i) 2 Carbons (acetic acid) CH3COOH

(ii) 3 Carbons (Propionic acid) CH3CH2COOH

(iii) 4 Carbons (Butyric acid) CH3(CH2)2COOH

Answer (C) These are the reaction when acetic acid loses one proton and become acetate.

CH3COOH + H2O CH3COO_ + H3O+

  

CH3COOH + NH3 CH3COO + NH+4