an acid is a proton (hydrogen nucleus) donor and a base is a proton (hydrogen nucleus) acceptor and the acid is dissociated after the proton is donated. An acid and its corresponding base are conjugate acid-base pairs.
acyl group
a functional group obtained from an acid by removal of a hydroxyl group (-OH). Usually the acyl group is derived from a carboxylic acid of the form RCOOH and therefore has the formula RC(=O)-, with a double bond between the carbon and oxygen atoms (i.e. a carbonyl group), and a single bond between R and the carbon atom. Acyl groups names are typically derived from the corresponding acid by substituting the acid ending -ic with the ending -yl (see table below); however, although methyl, ethyl, propyl, butyl etc. end in -yl, they are not acyl but alkyl groups derived from alkanes.
Acyl group name (R-CO-)
Corresponding carboxylic acid name (R-CO-OH)
common
systematic
common
systematic
formyl
methanoyl
formic acid
methanoic acid
acetyl
ethanoyl
acetic acid
ethanoic acid
propionyl
propanoyl
propionic acid
propanoic acid
benzoyl
benzoic acid
acryl
propenoyl
acrylic acid
propenoic acid
carbonyl
carbon atom double-bonded to an oxygen atom, C=O. The carbon of the carbonyl has a lone electron available that forms a chemical bond to the remainder R of the molecule.
carboxylic acids
organic acids with a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. Carboxylic acids are proton donors (Bronsted acids). Salts and anions of carboxylic acids are called carboxylates. The simplest series of carboxylic acids are alkanoic acids, R-COOH, where R is a hydrogen or an alkyl group. Compounds may also have two or more carboxylic acid groups per molecule.
