6.1.3 Carboxylic acids and esters Flashcards
What is the general formula for a carboxylic acid?
R-COOH
Describe the functional group of a carboxylic acid?
The carboxylic acid functional group consists of a carbonyl group attached to a hydroxyl group on the same carbon atom
Why do carboxylic acids have higher boiling points than alcohols of a similar molar mass c
Carboxylic acids can form multiple hydrogen bonds due to it having the hydroxyl and carbonyl groups
These stronger hydrogen bonds requires more energy to break leading to higher boiling points
What type of bonding explains the solubility of carboxylic acids?
Hydrogen bonding
What happens to solubility as the number of carbons increases?
less able to form hydrogen bonds with water
longer C-H chain so less able for
R-COOH to form hydrogen bonds with water
What happens when carboxylic acids react with metals?
Carboxylic acids react with metals to produce a salt and hydrogen gas
How do carboxylic acids react with metal oxides
Carboxylic acids react with metals to produce a salt and water
Describe the reaction of carboxylic acids and alkali?
Carboxylic acids react with alkalis to produce salt and water
What are the products of the reaction between carboxylic acids and carbonates ?
Carboxylic acids react with carbonates to produce a salt, water and CO2 gas
What is esterification?
Reaction between a carboxylic acid and alcohol in the presence of an acid catalyst
produces ester and water
What catalyst is commonly used in esterification of carboxylic acids?
Concentrated sulfuric acid
What functional group characterises esters?
R-COOR
How are esters formed from acid anhydrides and alcohols?
When acid anhydrides react with alcohols without the need for a catalyst
What is the product of acid hydrolysis of an ester
Acid hydrolysis of an ester produces a carboxylic acid and an alcohol
What are the products of alkaline hydrolysis of an ester?
Alkaline hydrolysis of an ester produces a carboxylate salt and an alcohol
How are acyl chlorides formed from carboxylic acids?
Acyl chlorides formed by reacting carboxylic acids and thionyl chloride
Why is thionyl chloride commonly used in the synthesis of acyl chlorides?
Thionyl chloride replaces the hydroxyl group in carboxylic acids with a Cl atom forming acyl chlorides and produces gaseous by products
What products are formed when acyl chlorides reacts with water?
forms carboxylic acids and releases HCl gas
What reaction occurs between acyl chlorides and alcohols?
esterification as esters form
Describe acyl chlorides reaction to form primary amide
Acyl chlorides reacts with ammonia to form primary amides
What formed when acyl chlorides react with primary amines?
Secondary amides
Why are acyl chlorides used to esterify phenol rather than carboxylic acids?
Acyl chlorides are more reactive than carboxylic acids
enabling them to esterify phenol, which doesnt readily react with carboxylic acids
What are some uses of carboxylic acids?
food preservation
pharmaceuticals
intermediates in chemical synthesis
What is the functional group present in acyl chlorides?
-COCl
How can you identify a carboxylic acid in the lab?
Carboxylic acids can be identified by their reaction with carbonates
producing CO2 gas - effervescence caused
What are some uses of esters?
sweet smells
flavourings
What is the overall reaction equation for the formation of acyl chloride?
RCOOH + SOCl2 = RCOCl + SO2 + HCl
Why must the reaction conditions be anhydrous?
ROCl forms RCOOH
How do you make CH3COCl?
React ethanoic acid with SOCl2
under anhydrous conditions to prevent hydrolysis of CH3COCl into CH3COOH
What is the overall reaction equation to convert acyl chlorides into esters?
RCOCl + ROH = RCOR + HCl
Why would you want to form an ester from acyl chloride?
better yield
What is the overall reaction equation for the formation of primary amides from acyl chlorides?
RCOCl + NH3 = RCONH2 +HCl
What is the overall reaction equation for the formation of secondary amides from acyl chloride?
RCOCl + RNH2 = RCONRH +HCl
What do all 4 reactions of acyl chlorides and others in synthetic routes form?
HCl
