Aromatic methylidene compounds, aromatic aldehyde compounds and methylstyryl compounds used to prepare the methylidene compounds, and methods for preparing these compounds

A compound selected from the group consisting of compounds of the following general formulas (2), (2a), (2b), (2c) and (2d):

• wherein R12 and R22 independently in each occurrence represent an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a halogen, a cyano group or a nitro group, n12 is an integer of 0, 1, 2, 3, 4, 5 or 6, and n22 is an integer of 0, 1, 2, 3 or 4 provided that when n12 and n22 are, respectively, an integer of 2 or more, R11's and R21's may be, respectively, the same or different;
• wherein R12a, R22a, n12a and n22a, respectively, have the same meanings as R12, R22, n12 and n22;
• wherein R12b, R22b, n12b and n22b, respectively, have the same meanings as R12, R22 n12 and n22;
• wherein R12c, R22c, n12c and n22c, respectively, have the same meanings as R12, R22 n12 and n22;
• and
• wherein R12bd, R22d, n12d and n22d, respectively, have the same meanings as R12, R22 n12 and n22.

A compound selected from the group consisting of compounds of the following general formulas (3), (3a), (3b), (3c) and (3d):

• wherein R13 and R23 independently in each occurrence represent an unsubstituted or substituted alkyl group, an unsubstituted or substituted alkoxy group, a halogen, a cyano group or a nitro group, n13 is an integer of 0, 1, 2, 3, 4, 5 or 6, and n23 is an integer of 0, 1, 2, 3 or 4 that when n13 and n23 are, respectively, an integer of 2 or more, R13″s and R23's may be, respectively, the same or different;
• wherein R13a, R23a, n13a and n23a, respectively, have the same meanings as R13, R23 n13 and n23;
• wherein R13a, R23a, n13b and n23b, respectively, have the same meanings as R13, R23 n13 and n23;
• wherein R13c, R23c, n13c and n23c, respectively, have the same meanings as R13, R23 n13 and n23;
• and
• wherein R13d R23d, n13d and n23d, respectively, have the same meanings as R13, R23 n13 and n23.