Organic Synthesis

Question 1

Curly arrows

Answer 1

A pair of elections being donated

Question 2

Heterolytic bond fission

Answer 2

Occurs when a covalent bond between two chemical species breaks in an unequal manner

Question 3

Homolytic fission

Answer 3

ions

Question 4

Heterolytic fission

Answer 4

ions

Question 5

Electrophile

Answer 5

attracted to negative charge. Electron defficient

Question 6

Nucleophile

Answer 6

attracted to positive charge, electron donates. E.g. water or ammonia

Question 7

SN1

Answer 7

first order nucleophilic substitution. Two steps. Positively charged carbocation formed

Question 8

SN2

Answer 8

second order nucleophilic sustitution. One step reactions, with a negative carbocation intermediate in between

Question 9

Tertiary haloalkanes

Answer 9

least likely to proceed by sN2, most likely to proceed by sN1

Question 10

Secondary haloalkanes

Answer 10

could be with sN1 or sN2

Question 11

Primary haloalkanes

Answer 11

most likely to proceed by sN2, least likely to proceed by sN1

Question 12

Primary/secondary/tertiary haloalkane

Answer 12

depends on how many hydrogens are attached to the carbon atom bonded to the halogen

Question 13

Elimination reaction

Answer 13

monohaloalkanes to form alkenes. Needs to be heated with ethanolic potassium or sodium hydroxide

Question 14

Substitution or elimination?

Answer 14

depends on solvent. If in water, it is substitution. If in ethanol, elimination

Question 15

Ethers

Answer 15

synthesised from haloalkanes and alkoxides

Question 16

Alkenes

Answer 16

prepared by dehydration of alcohols by aluminium oxides, concentrated sulphuric acid, or orthophosphoric acid

Question 17

Halogenation of alkenes

Answer 17

e.g. With bromine. The reaction with the cyclic ion intermediate

Question 18

Markovnikov’s rule

Answer 18

when H-X is added onto an unsymmetrical alkene the major product is one where the hydrogen bonds to the carbon atoms of he double bond that has already the greatest number of hydrogen atoms attached to it

Question 19

Carboxylic acids

Answer 19

oxidation of primary alcohols or aldehydes by heating them with acidified potassium dichromate. Hydrolysis of nitriles, esters or amides by heating them in the presence of a catalyst

Question 20

Carboxylic acids from haloalkanes

Answer 20

2 steps. Nucleophilic substitution to form a nitrile. Nucleophile is CN-. Then acid hydrolysis of a nitrile to produce a carboxylic acid

Question 21

Dimers

Answer 21

Form between two molecules of a concentrated carboxylic acid due to the hydrogen bonding

Question 22

Reduction of carboxylic acids

Answer 22

By using LiAlH4. Forms a primary alcohol

Question 23

amines

Answer 23

one or more of the hydrogen atoms have been replaced by an alkyl group

Question 24

Salts

Answer 24

amines react with hydrochloric acid, sulphuric acid, and nitric acid to form these

Question 25

Amines and carboxylic acids

Answer 25

form salts