carboxylic acids and derivatives Flashcards
What functional group characterizes carboxylic acids?
COOH functional group
Are carboxylic acids strong or weak acids?
Weak acids
What ions do carboxylic acids dissociate into in water?
Carboxylate ion and H+ ion
What physical property allows carboxylic acids to be soluble in water?
Ability to form hydrogen bonds
What happens to the solubility of carboxylic acids as chain length increases?
Solubility rapidly reduces
What is the reason for the high melting point of carboxylic acids?
They form hydrogen bonds with one another
How can carboxylic acids be identified?
By measuring melting point and comparing with known tables
What is the effect of the polarization of the carboxylic acid group?
It is open to attack from nucleophiles
What occurs when the hydrogen of the -OH group in a carboxylic acid is lost?
A carboxylate ion is formed
What is the stability of the carboxylate ion attributed to?
Negative charge is shared over the whole carboxylate group
What is the reaction of a carboxylic acid with a metal?
Carboxylic acid + metal → salt + hydrogen
What is produced when a carboxylic acid reacts with a carbonate?
Salt + water + carbon dioxide
What is the product of the reaction between a carboxylic acid and a metal hydroxide?
Salt + water
What is formed when a carboxylic acid reacts with ammonia?
Ammonium salt
What is esterification?
Carboxylic acid + alcohol ⇌ ester + water
What catalyst is typically used in esterification?
Strong concentrated H2SO4
What is the general reaction for acid hydrolysis of an ester?
Ester + water ⇌ carboxylic acid + alcohol
What is the product of base hydrolysis of an ester?
Salt of carboxylic acid + alcohol
What is the general formula for lipids?
3 fatty acids + 1 glycerol
What happens during lipid saponification?
Lipid + 3KOH → 3 salts of fatty acids (soap) + glycerol
What is produced when a lipid reacts with methanol?
3 methyl esters of fatty acids + glycerol
What are some uses of esters?
- Sweet smell in perfumes
- Flavoring in drinks/sweets
- Solvents in glues and inks
- Plasticizers in polymerization
What are acyl chlorides?
Derivatives of carboxylic acids by substitution of the -OH group with a chlorine atom
What is the process by which the acyl group is introduced into another molecule?
Acylation
What factors affect the reactivity of acylation?
- Magnitude of delta+ charge on carbonyl carbon
- Ease of leaving group loss
- Quality of nucleophile
What products result from acylation reactions with acyl chlorides or acid anhydrides?
- Carboxylic acid with water
- Ester with alcohol
- Amide with ammonia
- N-substituted amide with primary amine
What toxic byproduct is always produced when acyl chlorides react?
HCl
What is the advantage of using ethanoic anhydride over ethanoyl chloride in the synthesis of aspirin?
Cheaper, less corrosive, less vulnerable to hydrolysis, less dangerous
What is the equation for the formation of aspirin?
2-hydroxybenzoic acid + ethanoic anhydride → aspirin + ethanoic acid
