Question

a.Draw the structure of 3-quinuclidinone.

b.What is the approximate$\mathbf{pKa}$of its conjugate acid?

c.Which has a lower$\mathbf{pKa}$value, the conjugate acid of 3-bromoquinuclidine or the conjugate acid of 3-chloroquinuclidine?

Short answer

a.

b.$\mathbf{7}\mathbf{.}\mathbf{46}$

c.Conjugate acid of 3-bromoquinuclidine

Step-by-step solution

Step-by-Step SolutionStep 1:Structure of 3-quinuclidinone

The structure of 3-quinuclidinone is given below:

Structure of 3-quinuclidinone

In the name itself, it has –one group which indicates that there is a ketone group present in it. Also, the ketone is at the third position of the compound.

Finding the pKa value of conjugate acids

Conjugate acid is the one which accepts a proton.The $\mathrm{pKa}$value of conjugate acid of 3-quinuclidinone is $7.46$while role="math" localid="1652371462688" $\mathrm{pKa}$value of conjugate acid of morpholine is role="math" localid="1652371470215" $\mathbf{9}\mathbf{.28}$. Their structures are given below:

$\mathrm{pKa}$ value of conjugate acids

Comparing the  value of conjugate acids of 3-bromoquinuclidine and  3-chloroquinuclidine

Conjugate acid is the protonated compound. . So, the structures of conjugate acids of 3-bromoquinuclidine and 3-chloroquinuclidine are given below:

Conjugate acids