Topic 17.3 Carboxylic acids

(-oic acid suffix) O II R-C-OH

• Many reactions involve the loss of a H+ ion. • This produces a carboxylate ion where the charges are evenly distributed across C-O bonds.

• High boiling point due to presence of hydrogen bonds. • Boiling point increase with chain length (increased London forces). • Pure carboxylic acid, hydrogen bonding can occur between two molecules of acid to produce a dimer. • Shorter chains are soluble as they can form H bonds as they don’t contain a bulky group in the way. • Weakly acidic.

This uses a primary alcohol or aldehyde along with an oxidising agent, usually acidified potassium dichromate. CH3CH2CH2OH + 2[O] —> CH3CH2COOH + H2O

• Can be formed by hydrolysis of nitriles under reflux with either dilute or aqueous alkali. • Acidic hydrolysis: CH3CH2CN + H+ + 2H2O –> CH3CH2COOH + NH4^+ • Alkaline hydrolysis: CH3CH2CH2CN + OH- + H2O –> CH3CH2CH2COO- + NH3

Carboxylic acids can be reduced to primary alcohols, but not to aldehydes Reducing agent: lithium tetrahydridoaluminate (lithium aluminium hydride)

• Known as acid chlorides. • General formula: RCOCl. • The C in RCOCl is attached to 2 electronegative atoms, so it is electron deficient (this means it is susceptible to attack by nucleophiles).

-Colourless liquids -Relatively low melting points/ boiling points -Insoluble in water -Present in: perfumes, food flavourings, solvents -Pleasant smell

• Esters are formed from the reaction of an alcohol and a carboxylic acid. • Esters form in the presence of HCl or sulphuric acid (which acts as acids). • The O-H bond in the alcohol and the C-O bond in the carboxylic acid will break. • A new bond between the oxygen atom from the alcohol and the carbon atom in the carboxylic acid.

-Alcohol ends in -ly -Acid ends in -oate -Alcohol first, then acid

Involves an alkene monomer becoming a long chain polymer. (One product)

The joining of two monomers, with the elimination of a small molecule (eg. H2O) Polyesters are polymers that have monomers bonded via an ester link

There are two ways to form a polyester: 1) Two different monomers, a diol and a dicarboxylic acid (eg. Ethane-1,2-diol) 2) One monomer with -OH and -COOH groups (eg. Poly(lactic acid))