Haloalkanes

Question 1

What are haloalkanes?

Answer 1

(alkyl halides)
substituted alkanes in which one or more if the hydrogen atoms is replaced with a halogen atom

Question 2

what are monohaloalkanes?

Answer 2

-contain only 1 halogen atom

Question 3

what can monohaloalkanes be classified as?

Answer 3

-can be classified as primary, secondary or tertiary according to the number of alkyl groups attached to the carbon atom containing the halogen atom

Question 4

What reactions do halomonoalkanes take place in?

Answer 4

-elimination reaction: to form alkenes using a strong base r.g. potassium or sodium hydroxide in ethanol

nucleophilic substitution reactions with:
-aqueous alkalis to form alcohols
-alcoholic alkoxides to form ethers
-ethanolic cyanide to form nitriles (chain length increased by one carbon atom) that can be hydrolised to carboxylic acids

Question 5

what are the 2 different mechanisms that a monohaloalkane can take part in nucleophilic substitution reactions?

Answer 5

SN1 - nucleophilic substitution reactions with one species in the rate determining step and occurs in a minimum of 2 steps via a trigonal planar carbocation intermediate

SN2 - nucleophilic substitution reactions with 2 species in the rate determining step and occurs in a single step via a single 5-centred, trigonal bipyramidal transition state

Question 6

What can be used to explain if SN1 or SN2 will be the preferred mechanism for a given haloalkane

Answer 6

steric hindrance-

inductive stabilisation-