# Can NaH open the epoxide ring to form alcohol? If so, how?

I was looking at the organic chemistry 8th Ed textbook by Paula Yurknais Brucie. On page 509, I found this:

I think about it for a while and I am doubting that it is wrong. I believe the hydride ion itself cannot act as a nucleophile for SN2. (not really sure but I guess it is too small and too basic to work as a nucleophile, it should be much easier to attack hydrogen rather than carbon for hydride ion)

Is this reaction is possible with $$\ce{NaH}$$ in solvents other than water and alcohol? If so, how does the hydride ion open the epoxide ring? (hoping for an answer with mechanism)

And I am specifically talking about hydride ion (or hydrogen anion). Not sodium borohydride $$\ce{NaBH4}$$, lithium aluminum hydride $$\ce{LiAlH4}$$, or other metal hydrides.

• Well, there's no proton acidic enough, so it's gonna open the ring. Aug 21, 2021 at 18:14
• Going to have to be in aprotic solvent. NaH reacts vigourously with alcohols and water Aug 21, 2021 at 20:00
• I have been looking for this reaction and I find no examples. Nor in my limited experience of 40+ years can I ever recall seeing sodium hydride used as a source of nucleophilic hydride without some modifying agent (such as this example sciencedirect.com/science/article/abs/pii/S0040403900986313). Perhaps someone who has better database access than I can find it. Aug 21, 2021 at 20:47
• @Mithoron I don't think so. It is going to sit there and do nothing until it is worked up. Aug 22, 2021 at 19:12
• @MathewMahindaratne the answer you refer to concerns LiAlH4 opening of epoxides. It specifically excludes any reference to NaH even though the OP asked about NaH. Sep 1, 2021 at 10:24

## 1 Answer

Further to my comments above, I am going to offer my opinion that the book is wrong and the epoxide is not opened by sodium hydride as depicted. I have failed to find any literature examples of such a reaction and, in 40+ years as a synthetic chemist, I can recall no reactions in which $$\ce{NaH}$$, unmodified by other reagents, acts as a source of nucleophilic $$\ce{H-}$$.

Can anyone produce a literature example?

• @user55119 do you know of any examples? Aug 25, 2021 at 9:56
• I was as nonplussed as you when I saw this reaction of "naked" NaH. In my 40++ years I have not seen such a transformation. My Chem. Absts. search turned up only the reference in your Comment (DOI:10.1016/S0040-4039(00)98631-3). Textbooks are invariably riddled with errors and omissions. Aug 25, 2021 at 16:13
• Apropos of my final remark above, I once used a textbook that interpreted in great detail the fragmentation pattern of the EI mass spectrum of methyl propyl ether. Only one problem. The spectrum was that of diethyl ether! Aug 25, 2021 at 23:20
• @Waylander, maybe the textbook is incorrect and just makes up this reaction out of nowhere. I also cannot found any example in the literature. Thanks for the answer. Aug 26, 2021 at 12:26
• Kicked it around this evening at the pub with a synthetic chemistry colleague of similar experience - he also thinks this reaction will not occur. Aug 27, 2021 at 17:44