The invention relates to a process for the preparation of a compound of formula, wherein R represents a 2,3-dihydroxy-1-propyl or a 1,3-dihydroxy-2-propyl radical, via direct amidation of a dialkyl ester of 5-amino-1,3-benzenedicarboxylic acid of formula, wherein R1 represents a straight or branched -alkyl group, with at least the stoichiometric amount of an amine of formula H2NR. The dispenser has a reservoir for storing a liquid or solid material. The nut retains, rather than clamps, the grommet to the helmet. The mooring pendant apparatus operates as an extension of the boater’s arm, and it can be utilized either by keeping the apparatus on the boat or leaving it connected to the mooring line and also to the mooring ball. The air purifier can maintain the normal state of drive of the humidification filter by using a stepping motor and the control unit in order to vary the state of rotation of the humidification filter and thereby remove extraneous material when the humidification filter is rotating abnormally due to extraneous material. The invention also provides expression vectors, host cells, antibodies, agonists, and antagonists.