PROBLEM 12.38 - Organic Chemistry

Question

Draw the organic products formed when cyclopentene is treated with each reagent. With some reagents, no reaction occurs.

a. H₂+Pd-C

b. H₂+ Lindlar catalyst

c. Na ,NH₃

d. CH₃CO₃H

e. [1]. CH₃CO₃H [2] H₂O ,OH^-

f. [1] OSO₄+NMO [2] NaHSO₃, H₂O

g.KMnO₄ ,H₂O ,OH^-

h. [1] LiAlH₄ [2] H₂O

i. [1] O₃ .[2] H₃CSCH₃

j. (CH₃)₃ COOH ,Ti [OCH(CH₃)₃]₄  (-) DET

k. mCPBA

l.Product in (k); Then [1] LiAlH₄ [2] H₂O

Step-by-Step Solution

Answer

Answer

a.

b. No reaction occurs.

c. No reaction occurs.

d.

e.

f.

g.

h.No reaction occurs.

i.

j.No reaction occurs

k.

l.

Hydrogenation of cyclopentene

a. The above reaction is an example of catalytic hydrogenation, where the alkane gets reduced to alkane via syn-addition. 

The product is given below:

Reduction of cyclopentene

b. Lindlar catalyst can be used for the conversion of alkyne to alkene without further conversion to alkane.

Thus, an alkene is unreactive towards the reagent. Hence, no product is formed. 

 

c. The birch reduction acts on conjugated alkenes. Alkenes like cyclopentene would be unreactive towards such reaction due to lack of conjugation.

 

Epoxidation of cyclopentene and conversion to cis and trans diol

d. Upon reaction with  CH₃CO₃H, epoxide is formed as shown below:

Epoxidation of cyclopentene

e. The first step is epoxidation, and then the ion attacks at one of the centers. The final product is a trans-diol, as shown below:

Conversion of cyclopentene to trans-diol

f. The reaction is an example of dihydroxylation. Osmium tetra-oxide followed sodium bisulfide leads to the syn addition of hydroxyl group, and the product formed is given below:

Formation of cis-diol upon dihydroxylation 

g. KMnO₄ also leads to the syn addition of hydroxyl group to the compound, and falls under oxidation reactions. The product is given below:

Oxidation with 

h. The reagent is not capable of reducing simple alkenes. Thus, the following reaction will yield no product.

Oxidative cleavage of cyclopentene

i.The reaction is an example of oxidative cleavage of alkene to yield aldehydes and ketones

The product of the reaction would be:

Oxidative cleavage of cyclopentene

j. The reagent is known as the Sharpless reagent and is used to convert allylic alcohol to epoxide.

Since cyclopentene is a simple alkene, it is unreactive to the Sharpless reagent.

 

Epoxidation and epoxide ring opening of cyclopentene

k. The reaction of cyclopentene with mCPBA yields an epoxide, as shown below:

Epoxidation of cyclopentene using mCPBA

l. When the product formed in k is treated with LiAlH₄ ,H₂O cyclopentanol is produced, as shown below:

Reduction of epoxide to cyclopentanol