Under certain conditions, formaldehyde reacts with acetylacetone in the presence of ammonium acetate, forming a yellow product (3,5-diacetyl-1,4-dihydrolutidine) with absorption maximum at 412 nm.

Department of Catalysis & Fine Chemicals, CSIR- Indian Institute of Chemical Technology, Uppal Road, Hyderabad, Telangana State 500007, India ...