Question

1) True or False:

a) CH3Br is a more reactive electrophile than CH3Cl because Br is more electronegative than Cl

b) Iodide anion is a more reactive nucleophile than bromide anion.

c) Dehydrohalogenation of alkyl halides forms the trans-isomer as the major alkene product.

d)The (E)- and (Z)- alkene isomers are a pair of diastereomers.

e) The reaction between a secondary alkyl bromide and a sodium alkoxide salt (NaOR) gives a major product from nucleophilic substitution.

Answer 1

1)

a)False.

(Because as per Pauling's electronegetivity scale Cl is more electronegetive than Br and the electronegetivities in pauling's scale are Cl=3.0 and Br=2.8. Thus actually CH₃Cl is more electrophilic than CH₃Br)

b)True.

(As we know,softer the nuecleophile is, higher will be its nucleophilicity.Now iodide anion is softer than bromide as iodide is more polarizable.)

c)True.

This is explained in fig-I

d)True.

(The diastreomeric pair means they had same chemical formula but different physical properties.Now (E)- and (Z)- alkene are geometrical isomers and they had different physical properties thus they are diastereomeric pair.

e)False

e)False.

(As we know an S_N2 mode of reaction is always associated with E2 mode of reaction and higher the branching of alkyl part higher will be the yield of elimination product.And we have actually literature value given in fig-II)