Chemistry Unit 4 Flashcards
(50 cards)
Give the reactant(s), product(s) and conditions for the electrophilic substitution nitration of benzene
Reactants - benzene, conc. nitric acid and conc. sulphuric acid.
Product - nitrobenzene
Conditions - 50°C
Give the reactant(s), product(s) and conditions for the halogenation of benzene
Reactants – Benzene, bromine/chlorine
Catalyst – aluminium bromide/ aluminium chloride
Product – bromobenzene/ chlorobenzene
Conditions – room temperature and in the dark
Give the reactant(s), product(s) and conditions for the alkylation of benzene (Friedel-Crafts reaction)
Reactants - Benzene, chloromethane
Catalyst - aluminium chloride
Product - methylbenzene
Conditions - Reflux under anhydrous conditions
Compare how chloroalkanes and chlorobenzene react with NaOH
Chloroalkanes react easily in a nucleophilic substitution reaction.
The C-Cl bond in chlorobenzene is stronger as the lone pairs on the chlorine atom overlap with the π
electrons of the ring system so making phenol from chlorobenzene needs high temperatures and pressures.
Give the type of reaction and the conditions required for the reaction of primary/secondary alcohols to halogenoalkanes
Nucleophilic substitution reaction with OH- ion as the nucleophile
Reflux with aqueous solution of alkali (usually NaOH)
Give the reactant(s) and product(s) for the reaction of aldehydes or ketones to alcohols
Reactants - Aldehyde or ketone, aqueous NaBH4 (reducing agent)
Product - Aldehydes produce primary alcohols, ketones produce secondary alcohols
Give the reactant(s) and product(s) for the reaction of carboxylic acids to alcohols
Reactants - Carboxylic acid, LiAlH4 in ether (reducing agent)
Product - Primary alcohol
State the process for the reaction of alcohols to chloroalkanes
Pass HCl gas through alcohol with dry ZnCl2 as a catalyst.
State the process for the reaction of alcohols to bromoalkanes
Heat a mixture of the alcohol, KBr and concentrated sulphuric acid catalyst
State the process for the reaction of alcohols to iodoalkanes
By heating the alcohol under reflux with red phosphorus and iodine to produce PI3, and
this reacts with the alcohol.
State what occurs when an alcohol reacts with ethanoyl chloride and the advantages and disadvantages to this reaction in industry
An ester is formed, giving off misty fumes of HCl.
Better yield of ester than by using carboxylic acid as it’s not a reversible reaction.
Not cost effective in industry however, as acid chlorides are expensive.
State what occurs when an alcohol reacts with a carboxylic acid and the conditions for this process
An ester is formed.
Reactants refluxed together with concentrated sulfuric acid catalyst.
Remaining acid neutralised by NaHCO3 (aq)
State how an ester is collected after the reaction
Ester insoluble layer is removed using a separating funnel.
Ester is distilled and collected at its boiling temperature.
Give the reactant(s), product(s) and type of reaction for the reaction of phenol with bromine water
Reactants - Phenol, 3Br2
Products - The bromine water is decolourised and the 2,4,6-tribromophenol appears as a white precipitate
Type of reaction - Electrophilic substitution
Reaction of phenol with ethanoyl chloride
Form aromatic esters and HCl in an addition-elimination reaction. A base e.g pyridine can be added to speed up the reaction.
Oxidation of alcohols products, reactants and colour changes
Primary alcohols oxidised to aldehydes/carboxylic acids and secondary alcohols oxidised to ketones.
Oxidising agent is acidified potassium dichromate (orange to green) or acidified potassium manganate(VII) (purple to colourless).
What is 2,4-DNPH used to test for and what type of reaction occurs
A carbonyl group (C=O). Positive result gives a red-orange precipitate in a condensation reaction.
Give the reaction scheme and type of reaction for the formation of hydroxynitriles/hydroxycarboxylic acids from a carbonyl compound
Carbonyl compound + HCN forms hydroxynitrile then reflux and dilute sulfuric acid form the hydroxycarboxylic acid.
This is a nucleophilic addition reaction.
Give the order of acidity for ethanol, carboxylic acids, water and phenols
carboxylic acids > phenols > water > ethanol
Reaction of an alkylbenzene to a benzoic acid
Oxidising agent – alkaline potassium manganate(VII)
Colour change – purple to brown sludge
Alkaline solution produces the salt of the carboxylic acid which is then acidified with a dilute acid and crystals of benzenecarboxylic acid are formed.
Decarboxylation of carboxylic acids
Heat with soda lime (represented in equations as NaOH, Ca(OH)2 or CaO for simplicity). The carbon chain is reduced by one. Na2CO3 is often formed.
Acid hydrolysis of esters
Heat under reflux with aqueous sulphuric acid to produce the alcohol and acid.
Base hydrolysis of esters
Heat under reflux with aqueous NaOH.
Products are the alcohol and the salt of the carboxylic acid. The salt can then be acidified with HCl to form the acid.
Give two methods of converting carboxylic acids to amides
React with ammonia and then heat the ammonium salt that’s formed.
Heat the acid or its ammonium salt with urea (120⁰C)
