Chromene compound and curable composition

A naphthol compound represented by the following formula (6):

• wherein each of R1 and R2 is a sulfur-containing substituent represented by the following formula (2);
• in the above formula, ring X represented by the following formula is an aromatic hydrocarbon ring or aromatic heterocyclic ring, R3 and R4 are each independently an alkyl group, haloalkyl group, cycloalkyl group, alkoxy group, amino group, heterocyclic group containing a ring member nitrogen atom and bonded to the ring X bonded thereto via the nitrogen atom, halogen atom, aryloxy group or aryl group, “a” is an integer of 0 to 4, and when “a” is 2 to 4, a plurality of R4's may be the same or different;
• (ii) R1 is a sulfur-containing substituent represented by the above formula (2) and R2 is a hydrogen atom, hydroxyl group, alkyl group, haloalkyl group, cycloalkyl group, alkoxy group, amino group, heterocyclic group containing a ring member nitrogen atom and bonded to the 7-position carbon atom via the nitrogen atom, cyano group, nitro group, formyl group, hydroxycarbonyl group, alkylcarbonyl group, alkoxycarbonyl group, halogen atom, aralkyl group, aralkoxy group, aryloxy group or aryl group;
• or
• (iii) R2 is a sulfur-containing substituent represented by the above formula (2) and R1 is a hydrogen atom, hydroxyl group, alkyl group, haloalkyl group, cycloalkyl group, alkoxy group, amino group, heterocyclic group containing a ring member nitrogen atom and bonded to the 6-position carbon atom via the nitrogen atom, cyano group, nitro group, formyl group, hydroxycarbonyl group, alkylcarbonyl group, alkoxycarbonyl group, halogen atom, aralkyl group, aralkoxy group, aryloxy group or aryl group;
• R5 and R6 are each independently a hydroxyl group, alkyl group, haloalkyl group, cycloalkyl group, alkoxy group, amino group, heterocyclic group having a ring member nitrogen atom and bonded to an aromatic ring bonded thereto via the nitrogen atom, cyano group, nitro group, formyl group, hydroxycarbonyl group, alkylcarbonyl group, alkoxycarbonyl group, halogen atom, aralkyl group, aralkoxy group, aryloxy group, aryl group or sulfur-containing substituent represented by the above formula (2),
• R7 and R8 are each independently a hydrogen atom, hydroxyl group, alkyl group, haloalkyl group, cycloalkyl group, alkoxy group, alkoxyalkyl group, formyl group, hydroxycarbonyl group, alkylcarbonyl group, alkoxycarbonyl group, halogen atom, aralkyl group, aralkoxy group, aryloxy group or aryl group, and R7 and R8, together with the carbon atom bonded thereto, may form an aliphatic hydrocarbon ring having 3 to 20 ring member carbon atoms, condensed polycyclic ring having an aromatic hydrocarbon ring or aromatic heterocyclic ring condensed to the aliphatic hydrocarbon ring, heterocyclic ring having 3 to 20 ring member atoms, or condensed polycyclic ring having an aromatic hydrocarbon ring or aromatic heterocylcic ring condensed to the heterocyclic ring, “b” is an integer of 0 to 2, “c” is an integer of 0 to 4, when “b” is 2, two R5's may be the same or different, and when “c” is 2 to 4, a plurality of R6's may be the same or different.