Carboxylic Acids Flashcards
What makes a carboxylate acid soluble in water
The OH bond in the carboxylate acid forms hydrogen bonds
The COOH group is very soluble due to hydrogen bonding but the hydrocarbon chain is non-polar so doesn’t dissolve in water
Properties of short chain carboxylic acids compared to long cain
Short chain dissolve easily in water because the hydrocarbon chain is short
Long Chain- less soluble because the hydrocarbon chain is longer.
Reactivity of carboxyllic acids
Acts as acids because they can donate a H+
All CA are weak acids so the equilibrium lies over to the left.
How to form an ester
Carboxylic acid reacts with an alcohol, uses H2SO4 catalyst. Reaction is reversible, water is the buy product.
Hydrolysis of esters
Breaking bond using water
Acid catalysed: hydrolysed at room temperature using a strong acid catalyst. Equillibrium reaction so hard to get a high yield of carboxylic acid and alcohol
Base-catalysed hydrolysis
Using bases such as warm aqueous NaOH
Key points of base hydrolysis
Once the carboxyllic acid forms it reacts with the NaOH. This forms the salt of the acid. This increases the yield as it shifts the position of the equilibrium to the right. If the carboxyllic acid is the desired product then this method is not appropriate as the salt forms instead
Uses of esters
Animal fats and vegetable oils
Carboxylic acids formed from base hydrolysis in alkaline conditions can be used as soap.
Solvents for reactions
Plasticisers
Perfumes
Flavourings
Fatty acid dissociation in water
Polar head, dissolve in water. Non-polar chain , dissolves the grease.
Production of soap
Triglyceride + NaOH —-> 3 sodium carboxylate (soap) + glycerol
Production of biodiesel
Triglyceride + CH3OH + NaOH —> 3 methyl esters + glycerol
What is produced from each nucleophile
water- a carboxylic acid is the main product
Alcohol- an ester is the main product and HCL is formed
Ammonia- amide is the main product,HCL is formed
Amine- N-substituted amide is the main product
Why are industrial actuation reactions acid anhydrides used more than acyl chlorides
Anhydrides are cheaper
Less corrosive
Don’t react with water
Safer- side product is cooh compared to hcl vapours
Strong bases examples
Metal oxides- Na2O and MgO
Metal hydroxides - NaOH,KOH,Ba(OH)2
Weak alkalis
NH3,Na2CO3
Strong acid
HCL, H2SO4,HNO3,H3PO4
