A Level Edexcel Chemistry > Topic 17 > Flashcards

Topic 17 Flashcards

(25 cards)

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1
Q

Test for alcohols

A

Add Br2 this is a electrophillic addition reaction so it will decolourise

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2
Q

How to distinguish between butanal and butanol if both have orange precipitates when reacted with 2,4 DNP

A

Recrystallise and purify the precipitate
Measure melting point
Compare with known values

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3
Q

Molecules undergoing sn1 form racemic mixtures,why is this?

A

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

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4
Q

Why do sn2 reactions only produce 1 product

A

Only one enantiomer forms and nuc attacks on the opposite side of the leaving group

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5
Q

KCN reacts with carbonyl compounds to produce

A

Hydroxynitrile(Contains OH and CN)

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6
Q

What is reaction called between KCN and compounds with carbonyl groups

A

Nucleophilic addition

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7
Q

What products form when an unsymmetrical ketone or aldehyde reacts with KCN

A

Both hydroxynitrile enantiomers are formed

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8
Q

Risks and risk assessment of using potassium cyanide

A

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

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9
Q

How to make butanone from butan 2 ol

A

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

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10
Q

3 differences in esterificarion reaction between ethanoyl chloride with ethanol instead of ethanoic acid(3)

A

Ethanoic acid produces h20 whereas ethanoyl chloride produces hcl
Ethanoic acid and ethanol is a reversible reaction unlike EC and ethanol
Very fast reaction

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11
Q

In which compounds does optical isomers occur?

A

Optical isomerism occurs in compounds with 4 different groups of atoms attached to a carbon

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12
Q

Will a racemic mixture rotate in plane polarised light

A

No

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13
Q

How do racemates form in an SN1 reaction

A

CX bond breaks by heterolytic fission
OH- ion will attack trigonal planar carbon intermediate(from above or below) forming a racemate

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14
Q

Oxidation of aldehydes into carboxylic acids conditions and reagents

A

Potassium dichromate solution and dilute h2so4
Heat under reflux

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15
Q

Reduction of carbonyl(propanal) conditions and reagents

A

LiAlH4 in dry ether
Room temperature and pressure

Propanal + 2[H]—>Propan-1-ol

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16
Q

How to form hydroxonitriles

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A

Addition of HCN in the presence of KCN at room temperature and pressure

17
Q

Reduction of ketone(propanone) reagents conditions and product

Study These Flashcards
A

LiAlH4 in dry ether
Room temperature and pressure
Forming propan-2-ol

18
Q

Hydrolysis of Nitriles

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A

Nitrile into a carboxylic acid
Dilute HCl/H2SO4
Heat under reflux

19
Q

Reduction of CA to alcohols

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A

LiAlH4 in dry ether
Room temp and pressure,forms a primary alcohol

20
Q

Why do we not use a bunsen burner to warm aldehydes and ketones in Tollens reagent test

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A

Because they are flammable

21
Q

Overall reaction when iodine reacts with a carbonyl with a methyl group

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A

RCOCH3 + 3I2 + 4OH- –> RCOO- + CHI3 + 3H2O + 3I-

22
Q

How to form an ester

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A
  1. React Alcohol with a CA in Reflux(H2SO4 catalyst)
  2. Separate the ester through distillation
  3. Purify by adding sodium carbonate to remove remaining CA
  4. The top layer is the ester and use a separating funnel to obtain ester
23
Q

Explain ester hydrolysis and what catalyst is required and conditions

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A

Esters can be hydrolysed(react with water) to produce an alcohol and carboxylic acid.
Sulfuric/HCl and under reflux

24
Q

Explain ester base hydrolysis what it forms and conditions

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A

Use a dilute base to split ester into a carboxylate ion and an alcohol
Use NaOH under reflux

25
Explain how a polyester is formed
Formed by reaching a dicarboxylic acid and a diol Dicarboxylic acids have 2 COOH groups Diols have 2 alcohol groups
A Level Edexcel Chemistry
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