Carboxylic Acids Flashcards
chief chemical characteristic
acidity
generally more acidic than other organic compounds containing hydroxyl groups but are generally weaker than the familiar mineral acids (e.g., hydrochloric acid, HCl, sulfuric acid, H2SO4, etc.)
How are Carboxylic acids formed
hydrolysis of acid derivatives
oxidation of various compounds
hydrolysis of acid derivatives
yield carboxylic acids
conditions required range from mild to severe, depending on the compound involved easiest acid derivatives to hydrolyse are acyl chlorides, which require only the addition of water
Carboxylic acid salts are converted to the corresponding acids instantaneously at room temperature simply on treatment with water and a strong acid such as hydrochloric acid
Carboxylic esters, nitriles, and amides = carboxylic acid
less reactive and typically must be heated with water and a strong acid or base
If a base is used, a salt is formed instead of the carboxylic acid, but the salt is easily converted to the acid by treatment with hydrochloric acid.
Of these three types of
acid derivatives, amides are the least reactive and require the most vigorous treatment (i.e., higher temperatures and more prolonged heating). Under milder conditions, nitriles can also be partially hydrolysed, yielding amides: RCN → RCONH2.
Hydrolysis of Amides with Aqueous Acid
performed using aqueous acid
hydrolysis with SB is possible but more difficult
Solubility
in water is similar to that of alcohols, aldehydes, and ketones
Acids with fewer than about five carbons dissolve in water; those with a higher molecular weight are insoluble owing to the larger hydrocarbon portion, which is hydrophobic. The sodium, ammonium, and potassium salts of carboxylic acids, however, are generally quite soluble in water. Thus, almost any carboxylic acid can be made to dissolve in water by converting it to such a salt, which is easily done by adding a strong base—most commonly sodium hydroxide (NaOH) or potassium hydroxide, (KOH).
Boiling point
Carboxylic acids have much higher boiling points than hydrocarbons, alcohols, ethers, aldehydes, or ketones of similar molecular weight.
Carboxylic acids with higher molecular weights are solids at room temperature (e.g., benzoic and palmitic acids). Virtually all salts of carboxylic acids are solids at room temperature, as can be expected for ionic compounds
Esterification
carboxylic acids form esters when reacted with alcohol, heated in the presence of a mineral acid catalyst, form an ester and water
Alkanes general molecular formula
CnH2n+2
Alkenes general molecular formula
CnH2n
Alcohols general molecular formula
CnH2n+1OH
Carboxylic Acids general molecular formula
CnH2n+1COOH
Salt Formation
Carboxylic acids can react with bases to form ionic salts:
RCO2H + NaHCO3 —> RCO2– Na+ + CO2 + H2O
Decarboxylation of Carboxylic Acids
reaction of carboxylic acids, removing a carbon atom from a carbon chain. The end product usually produces CO2 as a byproduct.
