Boiling point hydrogen bonding, intermolecular

Among the nitrophenols, meta- and para-nitrophenols have high boiling points because of intermolecular hydrogen bonding, as shown below. 

Ethers are polar molecules. Compared to alcohols, ethers have very low boiling points mainly because they cannot form hydrogen bonds (intermolecular). The boiling points of ethers are close to alkanes of comparable weights. Ethers are not very reactive. 

In contrast, the a-anomer can only hydrogen bond intermolecularly, leading to a higher boiling point. 

The dotted lines represent hydrogen bonds. The high boiling point and viscosity of the pure acid indicate strong intermolecular forces of this kind. 

The physical properties of hydrofluorocarbons reflect their polar character, and possibly the importance of intermolecular hydrogen bonding (3). Hydrofluorocarbons often bod higher than either their PFC or hydrocarbon counterparts. For example, l-C H F bods at 91.5°C compared with 58°C for n-Q and 69°C for Within the series of fluorinated methanes, the boiling point reaches a maximum for CH2F2, which contains an equal... 

Amines, like ammonia NH3, are polar compounds and, except for tertiary amines, form intermolecular hydrogen bonds leading to higher boiling points than non-polar compounds of the same molecular weight, but lower boiling points than alcohols or acids. The smaller molecules, containing up to about six carbon atoms, dissolve in water. Aliphatic amines are similar in basicity to ammonia and form water-soluble salts with acids ... 

Methyl salicylate is the methyl ester of o-hydroxybenzoic acid. Intramolecular (rather than intermolecular) hydrogen bonding is responsible for its relatively low boiling point. 

Ihe boiling points of different molecular substances are directly related to the strength of the intermolecular forces involved. The stronger the intermolecular forces, the higher the boiling point of the substance. In the remainder of this section, we examine the nature of the three different types of intermolecular forces dispersion forces, dipole forces, and hydrogen bonds. 

Intermolecular hydrogen bonding raises boiling points and frequently melting points. 

They have dispersion and dipole-dipole intermolecular forces operating between their molecules. However, CH3CH2OH has hydrogen bonds operating between its molecules, and CH3OCH3 does not. Therefore, CH3OCH3 will have the lower boiling point. 

Melting points and boiling points are related to the strength of the intermolecular forces between solvent molecules, and to the molecular weight of the solvent. Dispersive forces, hydrogen bonding and permanent dipole moments all contribute. Typically, for molecules of similar mass, nonpolar compounds which... 

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