15.16: Formation of Amides

ECC: Introduction to General, Organic, & Biochemistry · LibreTexts

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    From LibreTexts, under CC BY-NC-SA 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.

    Learning Objectives
    • To describe the preparation procedure for amides.

    The addition of ammonia (NH3) to a carboxylic acid forms an amide, but the reaction is very slow in the laboratory at room temperature. Water molecules are split out, and a bond is formed between the nitrogen atom and the carbonyl carbon atom.

    Chemical equation showing CH3OH + H2 → CH3NH + H2O with labels "Reactants" and "Products."

    In living cells, amide formation is catalyzed by enzymes. Proteins are polyamides; they are formed by joining amino acids into long chains. In proteins, the amide functional group is called a peptide bond.

    Polyamides

    Just as the reaction of a diol and a diacid forms a polyester, the reaction of a diacid and a diamine yields a polyamide. The two difunctional monomers often employed are adipic acid and 1,6-hexanediamine. The monomers condense by splitting out water to form a new product, which is still difunctional and thus can react further to yield a polyamide polymer.

    Chemical equations showing reactants and products with arrows indicating the direction of the reactions.

    Some polyamides are known as nylons. Nylons are among the most widely used synthetic fibers—for example, they are used in ropes, sails, carpets, clothing, tires, brushes, and parachutes. They also can be molded into blocks for use in electrical equipment, gears, bearings, and valves.

    Key Takeaway

    • Amides are prepared by the reaction of a carboxylic acid with ammonia or an amine.

    15.16: Formation of Amides is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.