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Chemistry A2- Old > Unit 4 - Organic > Flashcards

Unit 4 - Organic Flashcards

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0
Q

What does Sn2 and Sn1 do ?

A

Sn2 Causes inversion whole Sn1 forms a carbocations intermediate

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1
Q

What are enantiomers?

A

Isomers that are mirror images of each other and have similar chemical and physical properties

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2
Q

What is the functional groups of ;
Aldehyde
Ketone
Carboxylic acids

A

Carbonyl group with CHO
Carbonyl group with CO
Carboxyl group with CO and OH

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3
Q

What type of reaction does carbonyl compounds undergo?

A

Nucleophilic reactions

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4
Q

What is the reaction between DNPH and a Carbonyl group

A

Orange/yellow precipitate
H20 formed
Nucleophilic substitution

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5
Q

What reaction occurs with Hydrogen Cyanide and conditions

A

Nucleophilic addition
With HCN in a catalyst of KCN in alkaline to provide CN-
Two step reaction
First reaction with CN- then with HCN with arrow from 0- to H-CN

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6
Q

Explain a reduction reaction of a carbonyl compound

A

Reagent is LiAlH4 in dry ether followed by hydrolysis of the intermediate by dilute acid
Nucleophilic addition
Forms a secondary alcohol if ketone is reduced
Forms a primary alcohol if aldehyde is reduced

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7
Q

Explain an Iodoform reaction involving a carbonyl compound

A

Compounds with COCH3 react
Warmed with iodine + few drop of alkali
Yellow insoluble precipitate formed

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8
Q

Explain oxidation of a carbonyl compound

A

Only aldehydes react as CHO reacts to form COOH or COO-

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9
Q

How to test for an aldehyde

A

With fehlings/Benedict -
Warmed
Red precipitate of copper oxide formed from blue solution
COO- + H20 formed

With tollens-
Warmed
Silver mirror formed
Oxidised to COO- + H20

With acidified potassium dichromate ions -
Warmed in sulphuric acid
Orange to green
Forms COOH

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10
Q

How to prepare a carboxylic acid

A

Oxidation primary alcohol or aldehydes
Under reflux
Solution of acidified potassium dichromate
Sulphuric acid present

Hydrolysis of nitriles
Nitrile heated under reflux
Dilute acid present
One step reaction

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11
Q

Reduction of Carboxylic acids

A

Oxidised back to alcohol only
LiAlH4 in dry ether
Room temp
H20 can be used to remove excess liAlH4

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12
Q

Reaction of carboxylic acid with phosphorus pentachloride

A

Halogenation reaction
Solid PCl5 used
Steamy fumes of HCl formed
Acyl chloride formed

E.g
CH3COOH + PCl5 —> CH3COCl + HCl + POCl3

HCl gas used as a test for OH group

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13
Q

Neutralisation reaction with Carboxylic acids

A

Reacts with a base to form salt + water

Salts are crystalline , soluble and ionic

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14
Q

Esterification of carboxylic acid

A

Warmed under reflux with alcohol
Concentrated sulphuric acid catalyst
Forms an ester

If product in cold water , sweet smell
Slow reaction with carboxylic Acid

To make it faster use an acyl chloride or acid anhydride

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15
Q

Acyl chlorides reaction with water

A

Forms a carboxylic acid + HCl

16
Q

Acyl chloride reaction with alcohols

A

Ester formed

At room temp on mixing

17
Q

Acyl chloride reaction with ammonia

A

Concentrated ammonia present
Amuse rapidly formed
No heat required

18
Q

Acyl chloride with amines

A

Substituted snide produced

Has CONH peptide link

19
Q

Ester reaction with acids in hydrolysis

A

Heated under reflux
Strong acid catalyst
Forms a Carboxylic acid + alcohol in equilibrium

20
Q

Ester reaction in base hydrolysis

A

Known as saponification
Boil with KOH or alkali
Forms alcohol and salt of carboxylic acid
Irreversible

21
Q

Explain transesterification

A

Ester + alcohol + alkaline catalyst

Used for low fat spreads and biodiesel

22
Q

Explain biodiesel

A

Vegetable oil such as glycerol and mainly unsaturated acids
They are too viscous
Therefore reacts with methanol in transesterification
Methyl ester is the biodiesel

23
Q

Explain low fat spreads

A

Vegetable oil is hardened to make margarine by hydrogenation
Forms trans isomers which are bad for the health
Partial transesterification with saturated acid
Replaces unsaturated acid

Chemistry A2- Old (9 decks)

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