What's with deuterium? an organic problem

[mooncrater]

Homework Statement

I did a question in which positive charge was unstable near to $-CD_3$ group but was stable near to $CH_3$ group.

Homework Equations

The Attempt at a Solution

Why is it like that? Is deuterium less active for hyperconjugation or it causes more steric hindrance? What's wrong with deuterium?

 

[Raghav Gupta]

How many neutrons or protons Deuterium has?

 

[mooncrater]

It has a proton and a neutron. So steric hindrance?

 

[Raghav Gupta]

It has a proton and a neutron. So steric hindrance?

I am not sure but it looks that it is the only reason. What do you think?

 

[mooncrater]

Yup.. it seems to me it's steric hindrance only, as it's heavier(thus bigger) than hydrogen. And it can't be hyperconjugation as it has the same configuration. That's what I think.

 

[Borek]

Do I understand correctly that you assume deuterium is larger than protium, because it has an additional neutron in nucleus? That must be off. The size of nucleus is negligible.

The only (in such cases) important difference is that D is twice heavier, so its reactions (broadly understood, not only in terms of pure chemistry, but also shape shifts) are much slower. I don't know what is the correct answer here, but that's the only valid approach IMHO.

 

[mooncrater]

IMHO

What is IMHO? Something molecular hybrid orbital?

 

[Raghav Gupta]

What is IMHO? Something molecular hybrid orbital?

In my humble opinion.

 

[mooncrater]

In my humble opinion.

Really? Okay...!