Carboxylic Acids and its Derivatives Flashcards
Functional group of carboxylic acids
RCOOH.
C=O and C-OH
Why are the intermolecular forces between carboxylic acid molecules relatively strong
Due to the presence of two polar groups, C=O and C-OH
Why do carboxylic acids have a higher boiling point than alcohols
Each carboxylic acid molecule can form 2 hydrogen bonds but each alcohol molecule can only form one. More energy is needed to break the hydrogen bonds between carboxylic acid molecules.
Why are some carboxylic acid molecules soluble in water
They can form hydrogen bonds with water molecules because it has a polar -COOH group. The -COOH group can form hydrogen bonds with water molecules. ONLY CARBOXYLIC ACIDS 1 to 4 are soluble
Why is benzoic acid only slightly soluble in water
The -COOH group can form hydrogen bonds with water molecules. However, it is only slightly soluble because the benzene ring is non-polar
Describe the reaction, conditions and reagents needed to go from a nitrile to a carboxylic acid
Reaction : Acid hydrolysis
Reagent : Dilute HCl
Conditions : Heat under reflux
nitrile + water + hydrochloric acid =
Carboxylic acid + ammonium chloride
Are carboxylic acids strong or weak acids
Weak. They only partially dissociate in solution
How are carboxylate salts produced
Acid-base reactions
ethanoic acid + NaOH ——–>
CH3-COO-Na+ + H2O
What are the reagents and conditions for acid-base reactions in the production of carboxylate salts
Reagent : AQEUOUS sodium carbonate/hydroxide
Conditions : Room temperature
propanoic acid + sodium carbonate =
sodium propanoate + water + carbon dioxide
What is the test for the -COOH group
Add aqueous sodium carbonate to the compound. Bubble the gas produced into limewater. Fizzing/effervescence is observed. The colourless gas (CO2) turns limewater cloudy
Describe esterification
When a carboxylic acid is heater under reflux with an alcohol in the presence of an acid catalyst such as conc sulfuric acid, an ester is formed
What do carboxylic acids do to carbonates even though they are weak acids
They liberate the CO2 from carbonates.
What type of reaction is it when esters are formed from the reaction between carboxylic acids and alcohols
Reversible reaction
Why is the yield of esters low when produced from reacting carboxylic acids and alcohols
It is a reversible reaction and results in an equilibrium therefore low yield
Reagents and conditions for esterification
Reagents: Alcohol and concentrated sulfuric acid
Conditions : Heat under reflux
How to draw esters
Break the -OH off the carboxylic acid
Break the H off the -OH on the alcohol
Connect the O of the alcohol to the main C of the carboxylic acid.
How to name esters
The alcohol part first and then the carboxylic acid part.
e,g, propyl ethanoate
Functions of concentrated sulphuric acid in esterification
Acts as the catalyst for the reaction
Absorbs the water formed, driving the equilibrium to the right and increasing the yield of the ester
Functional group for esters
-COOR
There is a C=O and and -OR attached to the same carbon
Common uses of esters
In solvents
Plasticisers
Perfumes
Food flavourings
Main use of polyesters
Clothing
How can esters be produced by acyl chlorides
When acyl chloride reacts with an alcohol at room temperature an ester and HCl is formed.
This reaction is called Nucleophilic addition-elimination
What is the advantage of making esters by reacting an acyl chloride with alcohol
The reaction goes to completion giving a higher yield of the ester
What is produced in the acid hydrolysis of esters
A carboxylic acid and an alcohol
Conditions and reagents for acid hydrolysis of esters
Conditions : Heat under reflux
Reagent: dilute HCl/H2SO4 - acts as catalyst
ester + water ———->
<———-
Carboxylic acid + alcohol
Describe what happens in acid hydrolysis of esters
Ester is heated with dilute HCl
C-O bond in ester is broken using water
Carboxylic acid and alcohol produced