# Does fumaric acid form stronger hydrogen bonds than maleic acid?

My book claims:

Fumaric acid can form intermolecular hydrogen bonds (strong) while maleic acid forms intramolecular hydrogen bonds (weak), hence fumaric acid has higher boiling point than maleic acid."

The intermolcular hydrogen bonds in fumaric acid are said to be stronger than the intramolecular hydrogen bonds in maleic acid, while I thought that intramolecular hydrogen bonds should be stronger than intermolecular hydrogen bonds. So, which one is correct?

• Which book is it? – DHMO Jan 21 '17 at 12:07
• ok I see but what I did not understand was at this level "fumaric acid can form intermolecular bonds (STRONG) and maleic acid intra(WEAK) " well then before i thought intramolecular bonds were stronger than intermolecular bonds, so I am completelly lost. – user40054 Jan 21 '17 at 12:09
• "The easy way Chemistry" – user40054 Jan 21 '17 at 12:14

Intramolecular hydrogen bonds do not have to be weak, but the strength of a hydrogen bond depends a lot on the $\ce{O-H\bond{....}O}$ angle. With intramolecular hydrogen bonds, it is often hard to achieve the perfect $180^\circ$ angle while the same is not a real exercise for intermolecular hydrogen bonds which have full degrees of freedom of movement on both sides.