I- CH3CH2I CH2-CH2-EtOH-III- D3C-CH2ID2C-CH2-EtOD-IIII- Me3C-I Me3C-OEt-Me2C-CH2IV- CD33C-ICD33C-OEt-CD32C-CD2Consider the given reactions-Which of the following statements is-are correct-

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Introduction to E2 Mechanism

I. CH3CH2I ...

Question

I. $C H_{3} C H_{2} I E t O^{-} - -- \to E 2 C H_{2} = C H_{2} + E t O H + I$
II. $D_{3} C - C H_{2} I E t O^{-} - -- \to E 2 D_{2} C = C H_{2} + E t O D + I$

III. $M e_{3} C - I E t O^{-} - ------ \to S N^{1} a n d E 1 M e_{3} C - O E t + (M e)_{2} C = C H_{2}$

IV. $(C D_{3})_{3} C - I E t O^{-} - ------ \to S N^{1} a n d E 1 (C D_{3})_{3} C - O E t + (C D_{3})_{2} C = C D_{2}$
Consider the given reactions.
Which of the following statement(s) is/are correct?

Reactions

(I)

and

(I I)

show primary kinetic isotope effect, whereas reactions

(I I I)

and

(I V)

show

2^{o}

kinetic isotope effect

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

Reactions

(I)

and

(I I)

show

2^{o}

kinetic isotope effect, whereas reactions

(I I I)

and

(I V)

show

1^{o}

kinetic isotope effect

No worries! We‘ve got your back. Try BYJU‘S free classes today!

All reactions show

1^{o}

kinetic isotope effect

No worries! We‘ve got your back. Try BYJU‘S free classes today!

All reactions show

2^{o}

kinetic isotope effect

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is C Reactions $(I)$ and $(I I)$ show primary kinetic isotope effect, whereas reactions $(I I I)$ and $(I V)$ show $2^{o}$ kinetic isotope effect
$(I)$ and $(I I)$ are $E 2$ reactions in which the R.D.S is breaking of $(C - H)$ or $(C - D)$ bond. Thus, $E 2$ elimination of $(I)$ is faster than that of $(I I)$ since, $(C - H)$ bond is weaker than $(C - D)$ bond. Hence, $(I)$ and $(I I)$ show $1^{o}$ kinetic isotope effect.

$(I I I)$ and $(I V)$ are either $E 1$ or $S_{N} 1$ reactions, which involve the formation of same intermediate ${M e}_{3} C^{\oplus}$ or ${({C D}_{3})}_{3} C^{\oplus}$ in R.D.S. This step does not involve any $(C - H)$ or $(C - D)$ bond breaking, so H/D effect is not $1^{o}$ but rather a small $2^{o}$ isotope effect, where $K_{H} / K_{D} = 0.7 / 1.5$ .

Reaction $(I I I)$ is faster than $(I V)$ , since, ${({C D}_{3})}_{3} C^{\oplus}$ is not as stable as ${M e}_{3} C^{\oplus}$ because, ${C D}_{3}$ is not as good as $¯ ¯ ¯ e$ -donator as ${C H}_{3}$ . Moreover $(C - D)$ is not a good hyperconjugative participant as $(C - H)$

Option A is correct.

Suggest Corrections

Similar questions

Question 16
Which of the following are the characteristics of isotopes of an element?

(i) Isotopes of an element have same atomic masses
(ii) Isotopes of an element have same atomic number
(iii) Isotopes of an element show same physical properties
(iv) Isotopes of an element show same chemical properties

(a) (i), (iii) and (iv)
(b) (ii), (iii) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)

Q. Which of the following is an incorrect statement?

a) Rate of formation of (II) and (IV)would be identical
b) Rate of formation of (I) would be slower than that of (III)
c) Formation of (I) would show primary isotope effect
d) Formation of (III) involves E1 reaction

Q. Nucleus P is converted into S through the following reactions

P \to Q + α

Q \to R + e^{-}

R \to S + e^{-}

Now a student figures out 4 conclusions from the above reactions as given below.
(i)R and S are isotopes
(ii) P and S are isotopes
(iii) Q and S are isotopes
(iv) Q and R are isotopes

Q. From the following nuclei, select the pairs of isotopes.

(i)_{92}^{238} U (i i)_{90}^{234} T h (i i i)_{92}^{234} U (i v)_{91}^{234} P a

Explain with examples (i) Atomic number, (ii) Mass number, (iii) Isotopes and (iv) Isobars. Give any two uses of isotopes.

Join BYJU'S Learning Program