28 - Organic synthesis

Question 1

reagents for: Alkene to haloalkane

Answer 1

Hydrogen halide
RTP
addition

Question 2

reagents for: alkene to primary alcohol

Answer 2

H20 (g) in the presence of phosphoric acid
addition

Question 3

reagents for: primary alcohol to aldehyde

Answer 3

gentle heating with acidifies potassium dichromate (oxidation)
K2Cr3O7/H2SO4
distil the reaction
orange to green

Question 4

reagents for: primary alcohol to carboxylic acid

Answer 4

heated strongly under reflux with excess K2Cr3O7/H2SO4
oxidation

Question 5

reagents for: Primary alcohol to haloalkane

Answer 5

heat under reflux
H2SO4 and sodium halide

Question 6

reagents for: secondary alcohol to ketone

Answer 6

K2Cr3O7/H2SO4
oxidation
reflux

Question 7

reagents for: haloalkane to alkene

Answer 7

NaOH (aq)
reflux

Question 8

reagents for: alkane to haloalkane

Answer 8

halogen/UV
substitution

Question 9

reagents for: aldehyde toe carboxylic acid

Answer 9

reflux with acidified dichromate (VI) ions Cr2O7 3-/H+
K2Cr3O7/H2SO4
oxidation

Question 10

reagents for: aldehydes to primary alcohols

Answer 10

NaBH4/H20
reduction

Question 11

reagents for: ketone to secondary alcohol

Answer 11

NaBH4/H20
reduction

Question 12

reagents for: aldehyde to hydroxyntrile

Answer 12

NaCN/H+
nucleophilic addition

Question 13

alkene to haloalkane

Answer 13

REACTANTS: Alkene and Hydrogen Halide (HX) or X2

CONDITIONS: Hydrogen Halide Gas or (concentrated) Hydrohalide Acid or Halogen Liquid (pure Br2) or halogen Water (Br2(aq))

PRODUCT(S): Haloalkane

REACTION TYPE: Electrophilic Addition

Question 14

alkene to alcohol

Answer 14

REACTANTS: Alkene and Steam (H2O(g))
CONDITIONS: Heat and Acid Catalyst (Phosphoric Acid,H3PO4)
PRODUCT(S): Alcohol
REACTION TYPE: Electrophilic Addition, (acid catalysed) Hydration

Question 15

why do you use an acid catalyst in the hydration of an alkene

Answer 15

Acid catalyst is required to form hydroxonium ion (H3
O+) ion that is able to act as an electrophile to start the reaction.

Question 16

how does an alkene react with Br2

Answer 16

Double bond in alkene polarises the bromine molecule to form an electrophile (Brδ+) that starts the
reaction.

Question 17

how do you test for the presence of a carbon-carbon double bond

Answer 17

Reaction can be used to test for the presence of an alkene. A sample is mixed with bromine water, if
the bromine water turns colourless (from orange - brown) an alkene is present in the sample

Question 18

alkene to alkane

Answer 18

REACTANTS: Alkene and Hydrogen, H2
CONDITIONS: Approximately 150oC and Nickel (solid) Catalyst
PRODUCT(S): Alkane
REACTION TYPE: Addition, Hydrogenation

Question 19

nitriles to haloalkanes

Answer 19

• Sodium cyanide NaCN or potassium cyanide KCN
• in ethanol
• length of the chain is increased

Question 20

aldehydes to nitriles

Answer 20

• reaction with hydrogen cyanide
• HCN is poisonous so a mixture of sodium cyanide and sulfuric acid

NaCN + H2SO4 -> HCN + Na2SO4

Question 21

ketones to nitriles

Question 22

nitriles to amines

Answer 22

• reduction reaction
• react with hydrogen with an acid catalyst

Question 23

what does propanenitrile hydrogen and a nickel catalyst form

Answer 23

propylamine
- a reduction reaction

Question 24

nitrile to carboxylic acid

Answer 24

react nitriles with dilute aqueous acid (HCl)and heat
- a hydrolysis reaction

Question 25

how to form butanoic acid from a nitrile

Answer 25

butanenitrile and dilute aqueous acid like HCl
butanenitrile + H2O + HCl -> butanoic acid + ammonium chloride

Question 26

what is alkylation (benzene)

Answer 26

• reaction that tranfers the alkyl group from haolalkane to benzene ring
• take place with AlCl3

Question 27

benzene to ethylbenzene

Answer 27

react with AlCl3 and C2H5Cl chloroethane
- HCl is formed

Question 28

acylation of benzene

Answer 28

• react with acyl chloride in the presence of aluminium chloride