Question

The most stable conformer of 1 2 ethane diol is

Answer 1

In the case of ethane-1,2-diol, the strain energy in the 5-membered ring formed by hydrogen bonding will be even less because some of the H−C−C−HH−C−C−H and C−C−C−CC−C−C−C interactions that produce the strain in cyclopentane are no longer present; the oxygens don't have the hydrogens attached like a methylene group does and the hydrogen used in the hydrogen bond is also much smaller than a methylene group.

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