Guanidine compound and heat sensitive recording material

A heat sensitive recording material comprising a substrate supporting thereon a heat sensitive recording layer containing a diazonium salt compound, a coupler which reacts with the diazonium salt compound when heated to develop color, and a base,

• wherein the heat sensitive recording layer includes as the base at least one of the guanidine compounds represented by the general formula (2):
• wherein in said general formula (2), R1 and R2 represent an alkyl group or aryl group and may be the same or different, and R3 represents an alkyl group or halogen atom;
• wherein the heat sensitive recording material comprises as the coupler at least one of the pyrrolo [1,2-a] pyrimidine compounds represented by the following general formula (5):
• wherein, in the general formula (5), R9 to R12 represent a hydrogen atom, halogen atom, aryl group, alkyl group, cyano group, acyl group, substituted carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, substituted sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, alkylphosphoryl group, arylphosphoryl group or substituted amino group;
• wherein said diazonium salt compound is at least one selected from compounds represented by the following general formula (6), compounds represented by the following general formula (7) and compounds represented by the following general formula (8):
• wherein, in said general formula (6), Ar represents a substituted or unsubstituted aryl group, each of R13 to R14 represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and may be the same or different, and X− represents an acid anion,
• wherein, in said general formula (7), each of R16, R17 and R18 represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group and may be the same or different, Y represents a hydrogen atom or —OR15 group, R15 represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and X− represents an acid anion,
• wherein, in said general formula (8), each of R19 and R20 represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and X− represents an acid anion.