Alkyl Halides

Question 1

Reactivity of alkyl halides depend on

Answer 1

Bond energy, polarity (more = more reactive) and bond length

Question 2

What is the hybridization of alkyl halides?

Answer 2

sp3

Question 3

C-Cl bond length in alkyl halide

Answer 3

178 pm

Question 4

Alkyl halide bond angle

Answer 4

109.5º

Question 5

Down the group, H-X reactivity

Answer 5

Increases

Question 6

H-X reactivity order

Answer 6

HI > HBr > HCl > HF

Question 7

The __ -carbon of alkyl halides is _____philic in nature

Answer 7

alpha-carbon is electrophilic in nature

Question 8

Halogen atom is a good __________ group

Answer 8

Leaving group

Question 9

The elimination reaction (dehydrohalogenation) of an alkyl halide gives an

Answer 9

Alkene

Question 10

The bond energy of HI is

Answer 10

228 kJ/mol

Question 11

The molecule undergoing nucleophilic reaction is called the

Answer 11

Substrate

Question 12

The group leaving the substrate/being replaced is called the

Answer 12

Nucleofuge

Question 13

Any species ________ or ___________ with an unshared pair of e- can act both as a base and a nucleophile

Answer 13

Neutral or negatively charged

Question 14

A nucleophile undergoes _________________ reactions

Answer 14

Nucleophilic substitution or addition reactions

Question 15

Bases give __________ reactions

Answer 15

Elimination reactions

Question 16

The positive carbon of alkyl carbocation is ____ hybridized and therefore has a __________ structure

Answer 16

sp2 and trigonal planar structure

Question 17

Alkyl groups are electron _______

Answer 17

Donating

Question 18

Carbocation stability order

Answer 18

Tertiary carbocation > Secondary carbocation > Primary carbocation > Methyl carbocation
(Most stable) (Least stable)

Question 19

Unimolecular substitution is ______ and _____ step mechanism

Answer 19

Unimolecular and two step mechanism

Question 20

SN1: First step is

Answer 20

Slow / rate determining

Question 21

SN1 mechanism is followed by

Answer 21

Tertiary alkyl halides

Question 22

SN1 mechanism is favored by ______ solvents (having _______ bonds)

Answer 22

Highly ionizing polar solvents (Polar protic). (having O-H , N-H bonds)

Question 23

SN1 has ______ nucleophile and _____ leaving group

Answer 23

Weak nucleophile and good leaving group

Question 24

SN1 follow _____ order kinetics

Answer 24

First order kinetics

Question 25

If nucleophile attacks carbocation from the side of the leaving group, the product shows _______ of configuration. If nucleophile attacks carbocation from the opposite side, the product shows _______ of configuration.

Answer 25

Side = Retention Opposite = Inversion (O and I are both vowels)

Question 26

Racemic Mixture is

Answer 26

When reactant is chiral, so a mixture of two enantiomers are produced

Question 27

Racemization is

Answer 27

A mixture of retention and inversion

Question 28

In SN1 there is _______ racemization

Answer 28

Partial

Question 29

In SN1 there is more _______ than ________

Answer 29

Inversion than retention (more opps in SN1)

Question 30

SN2 is _____ and ___ step

Answer 30

Bimolecular and one step

Question 31

SN2 is followed by ________

Answer 31

Primary carbocations and methyl halides

Question 32

SN2 follows _____ order kinetics

Answer 32

Second order kinetics

Question 33

SN2 is favored by _________ solvents

Answer 33

Polar aprotic solvents (aprotic means unable to ionize)

Question 34

SN2 goes thru _______ of configuration

Answer 34

Inversion only

Question 35

Secondary alkyl halides follow SN1 if __________, and SN2 if _______

Answer 35

SN1 if polar protic solvent present, SN2 if polar aprotic solvent present

Question 36

In 1,2 elimination, proton is removed from ___ position and halide is removed from ____ position

Answer 36

Proton from Beta, Halide from Alpha position

Question 37

SN2 has a ____ nucleophile and a ____ leaving group

Answer 37

Strong nucleophile and bad leaving group

Question 38

Which leaves first in 1,2 elimination

Answer 38

Beta first then alpha

Question 39

E1 is ____ and _______

Answer 39

Unimolecular and two steps

Question 40

E1 is followed by _____ alkyl halides

Answer 40

Tertiary

Question 41

E1 follows _____ order kinetics

Answer 41

First

Question 42

E1 has a ____ base

Answer 42

Weak base

Question 43

E1 needs _______ solvents

Answer 43

Polar protic solvents

Question 44

E2 is ___ and _____ step

Answer 44

Bimolecular and one step

Question 45

E2 follows ___ order kinetics

Answer 45

Second

Question 46

E2 prefers ______ solvents

Answer 46

Polar aprotic solvents

Question 47

E2 has a _____ base

Answer 47

Strong base

Question 48

E2 is followed by _____ alkyl halides

Answer 48

Primary

Question 49

Crowding around alpha carbocation generally favors _____ over _______. This is due to _______

Answer 49

Elimination over substitution. This is due to greater steric hindrance

Question 50

The greater number of alkyl groups favors _____ over ______

Answer 50

Elimination over substitution

Question 51

A stronger base will favor _____ and a stronger nucleophile will favor _______

Answer 51

Base will favor elimination and nucleophile will favor substitution

Question 52

2bromo propane with ethoxide ion (C2H5O-) vs with ethanthiolate ion (C2H5S-)

Answer 52

Ethoxide ion = Elimination Ethanthiolate ion = Substitution

Question 53

Order from strongest nucelophiles to strongest bases

Answer 53

I-, HS-, RS- > Br-, OH-, OR-, CH- > Cl, F, NH3, RCOO- > H2O, ROH Strongest Weakest (but Strongest Nucleophile Nucleophile Base)