I thought alcohol dehydration reactions formed alkenes, but if I understand you correctly then that’s not always the case.
I do know how the reverse of a Reformatsky reaction will form this “dehydration” product, but that would require zinc and wouldn’t be a dehydration reaction. If the reverse reformatsky reaction had a name I could maybe find literature that’d give me insight into the solution. But that would require zinc still and it would really just be the backwards mechanism, so probably wouldn’t be helpful...
Initially i wasn’t sure if the question itself was wrong, but I guess the dehydration proceeds in manner where no alkene intermediate is formed?
Basic conditions aren’t even favourable for dehydration reactions though... this question is so frustrating.