Question

Sort the following by boiling point, highest to lowest A N-methylethanamine B trimethylamine C propanamine Sort the following by boiling point, highest to lowest. A ethyl alcohol B ethyl amine C propane Why is the H-N-H bond angle in CH_3NH_2 105 degree while in aniline it is 118 degree ? a there is more steric hindrance in CH_3 NH_2 b there is less steric hindrance in CH_3 NH_2 c the N atoms in CH_3 NH_2 is sp^3 hybridized, but in aniline it is sp^2 d The lone pair electrons on N in aniline are part of an aromatic system

Answer 1

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Propanamine > N-methylethanamine > trimethylamine

As the branches increases the surface area decrease, which leads attraction of less number of molecules around it sothat it leads to low boiling point.

Straight chain compounds have high boiling point. As the branches increases the boiling point also increases accordingly.

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Ethyl alcohol > Ethanamine > Propane

Ethyl alcohol and ethanamine have hydrogen bonds among their molecules, but the strength of hydrogen bond is more than that of in ethanamine becuase oxygen is more electronegative than nitrogen. In propane only weak london forces exist.

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There is less steric hindrance in CH3NH2 compare to aniline. Because of presence of bulk phenyl ring.