4-Pentenal,2,2-dimethyl- , its cas register number is 5497-67-6. It also can be called 2,2-Dimethylpent-4-enal ; 2,2-Dimethyl-4-pentenal . 4-Pentenal,2,2-dimethyl- (CAS NO.5497-67-6) is a clear colorless to light yellow liquid.