carboxylic acids Flashcards
salicylic acid is precipitated out of a solution by adding dilute sulfuric acid until it is in excess; how could you tell the acid is in excess
no more precipitate formed
benzoic acid is sparingly soluble in water; explain this in terms of intermolecular forces
strong london forces between benzene rings; but can hydrogen bond with water
state three ways that acid hydrolysis of esters is different from alkaline hydrolysis
acid is a catalyst instead of a reagent; reaction is reversible (so lower yield); produces carboxylic acid (instead of its salt)
what reagent converts carboxylic acid to acyl chloride
PCl5
what reagent converts carboxylic acid to primary alcohol
LiAlH4
what reagent converts carboxylic acid to ester
alcohol
both carboxylic acids and acyl chlorides react with alcohols; state three differences between these reactions
acyl chloride reaction produces HCl instead of H2O; and does not need heat or a catalyst; and is not reversible so has higher yield
explain why old stocks of aldehyde react with sodium carbonate
aldehyde is oxidised to carboxylic acid by oxygen in the air
what do you see when carboxylic acid reacts with PCl5
white fumes (from HCl gas)
what is the solvent for the reaction of carboxylic acid with LiAlH4
dry ether
state the type of reaction that occurs between carboxylic acid and LiAlH4; justify your selection
reduction because the acid gains H
state the usual two conditions to speed up the reaction between carboxylic acid and alcohol
strong acid catalyst; heat under reflux
how to ensure maximum yield in oxidation of alcohol
heat under reflux; use excess oxidising agent
why does acyl chloride react faster than carboxylic acid (to make esters)
C-Cl bond weaker than C-O bond; carbonyl C is more +ve so attracts nucleophiles more
what are the products of acid hydrolysis of nitriles
carboxylic acid + ammonium ion
