In an earlier investigation it was found that 2-methyl-2-butene-l, 4-diol undergoes l, 4- dehydration readily under the influence of acidic reagents to give tiglic aldehyde.'This transformation of an unsaturated 1, 4-diol is related to the well-known dehydration rearrangements of saturated 1, 2-glycols and it seemed of interest in this connection to examine the behavior of 2, 5-dimethyIS-hexene-2, 5-diol (I), which is a vinylene homolog ( ...