Influence of the hydrogen bond on solubility

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Inter- and intramolecular hydrogen bonds

Hydrogen bonds occur not only in the compounds mentioned, but also in a large number of other compounds. A distinction is made between intermolecular and intramolecular hydrogen bonds. In non-polar solvents such as hydrocarbons and in the gas phase, carboxylic acids form intermolecular hydrogen bonds with dimerization.

In an aqueous solution, the carboxylic acid molecules can form hydrogen bonds with water, because both substances have correspondingly polarized hydrogen or oxygen atoms. Hydrogen bonds are not formed between carboxylic acid and hydrocarbon molecules because of the low polarity of the C-H bond, so that assembly in the manner shown is preferred.

Intramolecular hydrogen bonds exist in molecules such as 2-chlorophenol or salicylic acid.

Hydrogen bonds have a special function in proteins. They occur here between the N-H and C = O groups of neighboring polypeptide chains. The same applies to plastics of the polyamide type (nylon, perlon). After the stretching process, the hydrogen bridges ensure the extremely high tensile strength of the thread.

Hydrogen bridges play an important role in the solubility of substances in solvents. These issues are discussed in more detail in the Liquids section.