[xoggyux]

I need to find the reagents (an alkyl halide and a thiol) to synthesize a sulfide.
The thing is that a tertiary carbon is attached to the S atom (see picture) and it have me confused because then it means that the alkyl halide cannot be the tertiary carbon since there would not be any reaction due to steric hindrance, however I thought that steric hindrance would affect also the nucleophile (I am not sure about the last since the book does not say it specifically, I just assumed it would,) alternatively I thought the reaction could undergo SN1 pathway? (again I am not sure since the book only talks about SN2 for Thiols and sulfides) since there is a tertiary carbon, then the alkyl halide could dissociate (forming an stable tertiary carbocation) and then that carbocation could react with the nucleophilic SCH3.
Please help me find out which one of the two is the correct (or both?) or if both are wrong then give me some help to figure out the correct reagents.
Thanks.


Also I would like to confirm if (or if not) steric hindrance affects the nucleophile as well or it affects only the alkyl halide?

[plankk]

In my opinion the first one presents better way. Why? Because in the second one is high probability of elimination (E1).

What about steric hindarnce? I don't know exactly, but is likely (even certain) that it should influences on the nucleophile, and the primary thiolate will react faster than tertiary.

[StarvinMarvin]

In my view, also the first mechanism looks more feasible. What is more, the reaction procedure itself would be much easier. I don't know if you have worked with thiols before, but using methanethiol is at least nasty. It's very volatile and even a good fumehood won't protect you from its disgusting smell. I would much rather prefer to use iodomethane instead.

[xoggyux]

I thought of the first mechanism because is easier indeed and is also similar to most of the book's examples. However it requires that either the nucleophile or the alkyl halide have a "bulky" tertiary carbon to bond. The book specify consistently that tertiary alkyl halides are virtually unreactive when it comes to SN2 reaction due to steric hindrance. So thats why I used the bulky tertiary carbon in the nucleophillic species (the thiol) however I think I remember in my class the professor talking about nucleophiles not being effective if they were too bulky (I dont remember if she said specifically that they are unreactive, but the book does not say anything about them either)
So my question now is. Does nucleophiles of tertiary carbon are unreactive due to steric hindrance?

[Squirmy]

Steric bulk of the nucleophile will slow the rate of an SN2 down, but doesn't necessarily shut the reaction down completely.

A good example is t-BuO^-K⁺, which is often used when you want an E2 elimination to occur. The steric bulk of the nucleophile/base slows the SN2 pathway down and E2 predominates.

With your case, though, you're using methyl iodide as electrophile, which can't undergo E1 or E2 (or SN1 for that matter). Also, thiolates (RS-) are weak bases and excellent nucleophiles to begin with...the t-Bu may slow it down a bit, but it's going to work.

On a side note: t-BuSH has it's own problems with smell. It's one of the compounds added to natural gas to make leaks detectable. It also doesn't oxidize with bleach as well as other thiols. In short, if you use t-BuSH you should let everyone know or expect a visit from the fire dept.

[xoggyux]

Steric bulk of the nucleophile will slow the rate of an SN2 down, but doesn't necessarily shut the reaction down completely.

A good example is t-BuO^-K⁺, which is often used when you want an E2 elimination to occur. The steric bulk of the nucleophile/base slows the SN2 pathway down and E2 predominates.

With your case, though, you're using methyl iodide as electrophile, which can't undergo E1 or E2 (or SN1 for that matter). Also, thiolates (RS-) are weak bases and excellent nucleophiles to begin with...the t-Bu may slow it down a bit, but it's going to work.

On a side note: t-BuSH has it's own problems with smell. It's one of the compounds added to natural gas to make leaks detectable. It also doesn't oxidize with bleach as well as other thiols. In short, if you use t-BuSH you should let everyone know or expect a visit from the fire dept.

I am not actually going to make the reaction (I am sorry for not being clear enough,) I am studying for my final exam and was confused  , the book (like most books) only uses the "easiest" reaction for the example and then the questions (as well as exam questions) are a bit more complicated, sometimes I wish the book would not have so much "biographical" trivia and had more examples.

Thanks for all your answers.

[Squirmy]

I didn't think you were the comment about the smell was more a response to StarvinMarvin's comment about the nasty smell of CH₃SH

[xoggyux]

I didn't think you were the comment about the smell was more a response to StarvinMarvin's comment about the nasty smell of CH₃SH

N and S compounds have nasty smells 

[StarvinMarvin]

slightly off topic:

but in my opinion the nastiest smell of all is the smell of phenylacetic acid. (smells really terribly and it does not want to come off that easily).