Chemistry - CARBONYLS

What is the functional group in carboxylic acids?

-COOH

Carboxylic acids can be formed from the oxidation of?

primary alcohols

State the name of the oxidising agent used to form carboxylic acids from alcohols

acidified potassium dichromate

Are carboxylic acids weak or strong acids?

weak

Give the general equation for the partial dissociation of a carboxylic acid in water

RCOOH ⇌ RCOO^- + H⁺

Why do carboxylic acids have higher melting points than other organic compounds of a similar molecular weight?

They can form hydrogen bonds

What products are produced in neutralisation reactions between carboxylic acids and alkalis?

Salt + water

What products are produced in reactions between carboxylic acids and metal carbonates?

carbon dioxide + salt + water

What will be observed in a reaction between a carboxylic acid and a metal carbonate?

effervescence

Identify the chemical test for the presence of carbon dioxide

limewater turns cloudy

What products are produced in reactions between carboxylic acids and metals?

salt + hydrogen

What type of reaction occurs between carboxylic acids and metals?

redox

Carboxylic acids can be reduced back to alcohols using which reducing agent

LiAlH₄

What is produced when a carboxylic acid reacts with an alcohol?

ester + water

Esterification is an example of what type of reaction?

condensation

What is used as the catalyst in esterification reactions?

strong acid catalyst - concentrated sulfuric acid

The reverse of a condensation reaction is known as …

hydrolysis

The functional group for esters is …

RCOOR’

Give the conditions required for acid hydrolysis of esters

reflux and dilute strong acid (Hydrochloric or sulfuric)

Give the conditions required for base hydrolysis of esters

reflux and dilute strong alkali (Sodium hydroxide)

Why is base hydrolysis the preferred method over acid hydrolysis of esters?

Not a reversible reaction

What is the role of the hydroxide ion in base hydrolysis of esters?

Nucleophile

What is a triglyceride?

An ester/fat/lipid

What is the IUPAC name for glycerol?

propane-1,2,3-triol

Saturated means the substance contains …

no double bonds

Base hydrolysis of an ester is also known as 

saponification

Saponification is a reaction to produce what useful product

soap

Soap is produced when fats/lipids react with what other reagent?

sodium hydroxide

If fats/lipids react with methanol , what useful product is produced ?

methyl esters - biodiesel

Give at least 2 uses of esters

fragrances, flavourings, plasticisers

When acyl chlorides react with water, alcohols, ammonia and primary amines what observation is seen ?

misty fumes of HCl

What products are formed when acyl chlorides react with water?

alcohol + HCl

What products are formed when acyl chlorides react with alcohols?

ester + HCl

What products are formed when acyl chlorides react with ammonia?

amine + HCl

What products are formed when acyl chlorides react with primary amines?

secondary amines + HCl

Name the mechanism in which acyl chlorides/anhydrides can react with water, alcohols,ammonia and primary amines?

nucleophilic addition - elimination

Give an advantage of using an acid anhydride over an acyl chloride

safer, less vigorous reaction, carboxylic acid produced instead of HCl (toxic)

Give an advantage of using an acyl chloride over an acid anhydride

faster reaction

Identify the process used to purify organic solids and remove impurities

recrystallisation

How can purity of an organic solid be determined?

Measuring melting point - pure substances have sharp melting point

Identify a suitable drying agent

an anhydrous salt

What equipment is used to separate immiscible liquids

separating funnel