Chapter 26.3- Carboxylic acids and their derivatives Flashcards
What is a carboxylic acid?
An organic molecule with the -COOH functional group, with a C=O carbonyl group and -OH acid group.
How are carboxylic acids produced?
Oxidation of primary alcohols under reflux (alcohol to aldehyde to carboxylic acid)
How do carboxylic acids dissociate?
Carboxylic acids are weak acids so they slightly dissociate when in solution, forming an H+ ion and carboxylate ion RCOO-
How do carboxylic acids react with carbonates?
They react as acids producing a carboxylate salt, water and CO2
What is the chemical test for a carboxylic acid?
React with a carbonate NaHCO3 and observe for fizzing or bubble through limewater
How soluble are carboxylic acids?
Small chain carboxylic acids form H- bonds with water molecules due to lone pair on O from water and δ+ H in -OH group, making them soluble in water.
Longer chain carboxylic acids are less soluble
What is the esterification reaction?
Carboxylic acids react with alcohols with a strong acid catalyst to produce an ester and water.
RCOOH + ROH –> RCOOR’ + H2O (with strong acid catalyst)
What is easy to remember in the esterification reaction?
-OH group from carboxylic acid and H from alcohol group are removed and form water, the R groups remaining join together
What are the conditions for the esterification reaction?
Strong acid catalyst and heat
How do you name esters?
Start with alkyl group ending with -yl, then other part with COO ending with -oate.
Carbon atoms either side of central O are number 1
What are some properties of short chain esters?
Volatile, sweet smelling, good solvents for polar molecules
What are esters?
Organic molecules with a -COO- group
What are some uses of esters?
Perfumes, food flavourings, solvents, plasticisers
What are animal fats and vegetable oils?
Esters of naturally occurring glycerol (propane- 1,2,3- triol), they are tri (glyceride) esters
What happens when glycerol undergoes esterification?
It forms triglyceride esters
What happens when carboxylic acids dissociate?
They lose the H from the -OH group and the negative charge is shared over the carboxylate group, making the ion more stable
What is ester hydrolysis?
The reverse reaction to esterification, converting esters back into carboxylic acids and alcohols. Water is added and depending on conditions different products are formed
What happens in acid hydrolysis?
Ester reacts with water to produce carboxylic acid and alcohol (with acid catalyst)
What are some features of acid hydrolysis?
Reversible, low yield, slow, acid catalyst at RT
What happens in alkaline hydrolysis?
Ester reacts with water then further with base, eg NaOH to produce a carboxylate salt, eg RCOONa and an alcohol
What is saponification?
Producing the carboxylate salt in alkaline hydrolysis
What are carboxylate salts commonly used for?
Soap and detergents
Why are carboxylate salts used in soaps?
They have an ionic, polar head which is hydrophilic and a non-polar, hydrophobic tail. The tail will mix with grease and the head mixes with water, allowing the two to mix
What happens when animal fats or vegetable oils are boiled with NaOH?
Saponification reaction in which glycerol from triglyceride esters and sodium salts are produced
What is transesterification and what is an example reaction?
The conversion of one ester into another, eg in the production of biodiesel
How is biodiesel produced?
By reacting vegetable oils with methanol with a strong alkali catalyst to produce a mixture of methyl esters and glycerol
What is biodiesel?
A mixture of methyl esters of long chain carboxylic acids
What is an acid anhydride?
An organic molecule formed with water removed from two carboxylic acids
How do acid anhydrides react?
Undergo the same reactions as carboxylic acids but do not require a catalyst, only heat, as they are more reactive
What are acid/ acyl chlorides?
Organic molecules with the -COCl group
What are primary amides?
Organic molecules with the -CONH2 group
What are N-substituted amides?
Amides in which a H from the NH2 group is replaced by something else, eg methyl, phenyl, etc.
How do acyl chlorides react?
They are very reactive and require no catalyst or heat, however they produce toxic HCl and are expensive
What mechanism and conditions do the derivatives react via?
Nucleophilic addition-elimination, under aqueous conditions
What is produced from an acyl chloride and and water?
Carboxylic acid and HCl
What is produced from an acyl chloride and alcohol?
Ester and HCl
What is produced from an acyl chloride and ammonia?
Amide and HCl
What is produced from an acid anhydride and water?
Two carboxylic acids
What is produced from an acid anhydride and alcohol?
Ester and carboxylic acid
What is produced from an acid anhydride and ammonia?
Amide and carboxylic acid
What is produced from an acid anhydride and primary amine?
N-substituted amide and carboxylic acid
What is the outline for nucleophilic addition-elimination?
Lone pair of nucleophile moves to C in carbonyl group
Atom with lone pair bonds and now has positive charge
Electrons from bond between H and positive charge move to atom, releasing H+
Electrons from pi bond move back to C in carbonyl group
Electrons from bond between C and remaining group move to the remaining group
What is the reaction for aspirin?
Salicylic acid (carboxylic) reacts with ethanoic anhydride (acting as alcohol) to production aspirin (ester) and ethanoic acid (carboxylic)
