Topic 17
No description yet. This curated deck is ready for daily study.
Card preview (24)
Test for alcohols
Add Br2 this is a electrophillic addition reaction so it will decolourise
How to distinguish between butanal and butanol if both have orange precipitates when reacted with 2,4 DNP
Recrystallise and purify the precipitate Measure melting point Compare with known values
Molecules undergoing sn1 form racemic mixtures,why is this?
Due to the planar nature of the carbocation there is an even chance of nucleophile attacking from above or below So there is a 50 50 of both enantiomers forming
Why do sn2 reactions only produce 1 product
Only one enantiomer forms and nuc attacks on the opposite side of the leaving group
KCN reacts with carbonyl compounds to produce
Hydroxynitrile(Contains OH and CN)
What is reaction called between KCN and compounds with carbonyl groups
Nucleophilic addition
What products form when an unsymmetrical ketone or aldehyde reacts with KCN
Both hydroxynitrile enantiomers are formed
Risks and risk assessment of using potassium cyanide
KCN is an irritant and very dangerous if inhaled If KCN reacts with moisture they can form HCN Use a fume cupboard to stop exposure to toxic fumes
How to make butanone from butan 2 ol
Oxidise butan2ol with Potassium dichromate in a conical flask connected in reflux Set up apparatus using a vertical condenser,flask,bumping reactants and heat Distillation with sloping condenser Anhydrous CaCl2 as drying agent Filtration to remove CaCl2 from butanone Redistil product
3 differences in esterificarion reaction between ethanoyl chloride with ethanol instead of ethanoic acid(3)
Ethanoic acid produces h20 whereas ethanoyl chloride produces hcl Ethanoic acid and ethanol is a reversible reaction unlike EC and ethanol Very fast reaction
In which compounds does optical isomers occur?
Optical isomerism occurs in compounds with 4 different groups of atoms attached to a carbon
Will a racemic mixture rotate in plane polarised light
No
How do racemates form in an SN1 reaction
CX bond breaks by heterolytic fission OH- ion will attack trigonal planar carbon intermediate(from above or below) forming a racemate
Oxidation of aldehydes into carboxylic acids conditions and reagents
Potassium dichromate solution and dilute h2so4 Heat under reflux
Reduction of carbonyl(propanal) conditions and reagents
LiAlH4 in dry ether Room temperature and pressure Propanal + 2[H]—>Propan-1-ol
How to form hydroxonitriles
Addition of HCN in the presence of KCN at room temperature and pressure
Reduction of ketone(propanone) reagents conditions and product
LiAlH4 in dry ether Room temperature and pressure Forming propan-2-ol
Hydrolysis of Nitriles
Nitrile into a carboxylic acid Dilute HCl/H2SO4 Heat under reflux
Reduction of CA to alcohols
LiAlH4 in dry ether Room temp and pressure,forms a primary alcohol
Why do we not use a bunsen burner to warm aldehydes and ketones in Tollens reagent test
Because they are flammable
Overall reaction when iodine reacts with a carbonyl with a methyl group
RCOCH3 + 3I2 + 4OH- –> RCOO- + CHI3 + 3H2O + 3I-
How to form an ester
• React Alcohol with a CA in Reflux(H2SO4 catalyst) • Separate the ester through distillation • Purify by adding sodium carbonate to remove remaining CA • The top layer is the ester and use a separating funnel to obtain ester
Explain ester hydrolysis and what catalyst is required and conditions
Esters can be hydrolysed(react with water) to produce an alcohol and carboxylic acid. Sulfuric/HCl and under reflux
Explain ester base hydrolysis what it forms and conditions
Use a dilute base to split ester into a carboxylate ion and an alcohol Use NaOH under reflux