substitution

Question 1

how does substitution occur?
1. SN1
2. SN2
Are they exomthermic or endothermic

Answer 1

it is the reaction between l.g. and nu-
1. lg leaves first then nu- attacks
2. lg ‘s leaving and nu- add takes place simultaneously

Exothermic

Question 2

Rate of SN1 is directly dependent on?

Answer 2

1. R-X conc
2. C+ stabilty before rearrangement
3. X- stability
4. presence of EWG(stronger the ewg quicker and easier will be the rds step)

since it is the rds step in SN1 .i.e. R-X–> R+ + X-

Question 3

how does nature of substrate effect rate of SN1

Answer 3

substituted benzylic>3RX>benzylic>allylic
R-X -3 º > 2 º > 1 º

Question 4

nature of leaving group effect in SN1
(same for SN2)

Answer 4

better lg=>more rate
R-I > R-Br > R-Cl > R-F

Question 5

nature of solvent where Sn1 if favoured

Answer 5

pps

it solvates both R+ AND X-

Question 6

nature of solvent where Sn2 if favoured

Answer 6

paps

Question 7

attack in SN1 takes place from which side

Answer 7

practically, IOC
theoretically, IOC%=ROC%

ROC= FRONT(not rear) IOC=BACK(inversion)

Question 8

basic difference b/w SN1 and SN2

Answer 8

SN1- C+ stability, becuz R+ rds mein banta hai
SN2- less steric hinderance becuz one step process, nu- tabhi lagega agr crowding na ho rahi ho

Question 9

SN2 roc or ioc

Answer 9

Always IOC(back side), to avoid steric hinderance

Question 10

Rate of SN2 depends upon

Answer 10

• Stability of T.S.
• EWG
• Nu- Concn.

Question 11

Nature of substrate in R-X in SN2

Answer 11

R-X: 1 º > 2 º > 3 º

Question 12

Rate of SN2 @hinderance

Answer 12

unhindered> α hindered> βhindered

Question 13

R-X + NaI(acetone) gives

Answer 13

R-I +NaX

Finklestein reaction SN2

Question 14

R-X + [AgF, HgF2, SbF5]MF- gives

Answer 14

R-F + MX

Question 15

ETHER* [R1-O-R2 ]* + H2O/H+(acidic hydrolysis)

Answer 15

R1-OH + R2-OH

Question 16

R1-O-R2 + HI gives

Answer 16

R1/R2I +R1/R2-OH
depending upon less steric hinderance in anhydrous
aqueous mein oh oh lege ga