Question

melting point of cis -butene is lower than that of trans 2 butene . why?

Answer 1

There are a lot of reasons for that--

1. In Trans2butene The bulky group are on opposite sides.Thus it has less steric repulsion among the Heavy group leading to More symmetrical shape than Cis form..Thus it has better packing and hence higher M.P

also..Boiling point depends upon intermolecular interactions which over here is more in cis due to its net dipole moment . The dipole moment enables electronic interactions which hold molecules together .Opposite is the case for Trans 2 butene