Pyrimidine-substituted examples of this functional group are autocatalytically alkylated in the Soai reaction. This functional group is condensed with ammonia and hydrogen cyanide in the first step of the Strecker synthesis. Applying (-5[1])DIBAL-H (DIE-bow H), followed by aqueous workup, reduces nitriles to this functional group. Treating a primary alcohol with pyridinium chlorochromate [emphasize] mildly oxidizes it to this functional group, rather than a carboxylic acid. A “silver mirror” forms when this functional group produces a (10[1])positive result in the most common application of the Tollens test. The simplest compound with this functional group has the formula CH2O and is a common biological preservative. For 10 points, name this functional group composed of a terminal carbonyl group, unlike a ketone. (10[1])■END■