NEW MATERIAL:The compound of formula I (R1 is 8W18C alkyl; R2 is H or lower alkyl).

EXAMPLE: 1-Hydroxy-4-methylnaphthalene-8-N-stearyl-sulfonamide.

USE: Useful as a coupling component of a diazo-type heat-sensitive recording material. It does not cause the fogging of the recording material, and has low melting point and high thermal sensitivity. Since the compound can be supercooled, there is no sticking problem with a thermal head in thermal printing. It has excellent compatibility with waxy binders and agents for imparting supercooling capability.

PROCESS: The compound of formula I can be prepared by the coupling reaction of a diazo compound of formula II (R3 and R4 are 1W6C alkyl, etc.; Y1 and Y2 are H, etc.; when both Y1 and Y2 are alkoxy, they are in the para-position with each other; X is acid residue, etc.), etc.