| 摘要 |
NEW MATERIAL:Compds. of formula I, wherein R<1> and R<2>, R<3>, R<4>, R<5> and R<6> are each an alkyl. EXAMPLE:A compd. of formula II. USE:The title derivatives which are photochlromic dyes which reversibly form red color by ultraviolet radiation and turn original light yellow when irradiated with visible light and are useful as recording materials, memory materials, copying materials, dimming materials, sensitized materials for printing, etc. PREPARATION:A 4-cyanomethyl-2,3,5-trialkylthiophene of formula III is condensed with a compd. of formula IV in a solvent consisting of water and an org. solvent (e.g., CCl4) and in the presence of a phase transfer catalyst (e.g., triethylbenzylammonium chloride) at an alkaline pH and a temp. of room temp. to 100 deg.C. |
