On December 20, 2001, Gross, Wibke; Hoeffkes, Horst; Martin, Hans-Dieter; Moeller, Hinrich; Oberkobusch, Doris published a patent.Quality Control of 2-(2,3-Dihydro-1H-inden-1-ylidene)malononitrile The title of the patent was Hair dyeing compositions containing oxocyclopentenes. And the patent contained the following:
Hair dyes contain oxocyclopentene derivative (I, R1 and R2 = H, or a C1-4 alkyl, R3 and R4 = H, C1-4 alkyl or group of aryls, the remainder of R1 and R2 and/or R3 and R4 can form a ring, and X = C:O, C:S or CH2). Thus, 2,5,5-trimethyl-3-oxocyclopent-1-enecarboxaldehyde (II) was prepared and used in a formulation consisting of II 8, Natrosol 250HR 2.0 and water to 100 g. The experimental process involved the reaction of 2-(2,3-Dihydro-1H-inden-1-ylidene)malononitrile(cas: 2510-01-2).Quality Control of 2-(2,3-Dihydro-1H-inden-1-ylidene)malononitrile
The Article related to oxacyclopentene hair dye preparation, Essential Oils and Cosmetics: Hair Preparations and other aspects.Quality Control of 2-(2,3-Dihydro-1H-inden-1-ylidene)malononitrile
Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts