Vinylogy the α-carbon immediately adjacent to the carbonyl, as would a simple enolate. Allylic electrophiles often react by vinylogous attack of a nucleophile rather than direct addition. A further example of vinylogous reactivity: ascorbic acid (Vitamin C) behaves as a vinylogous carboxylic acid by involvement of its carbonyl moiety, a vinyl group within the ring, and the lone pair on the hydroxyl group acting as the conjugated system. Acidity of the hydroxyl proton at the terminus of the vinyl group in ascorbic acid is more comparable to a typical carboxylic acid than an alcohol because two major resonance structures stabilize the
Vitamin C had proven this, but published the result without giving Szent-Györgyi credit for it. This led to a bitter dispute over priority. In 1933, Walter Norman Haworth chemically identified the vitamin as -hexuronic acid, proving this by synthesis in 1933. Haworth and Szent-Györgyi proposed that L-hexuronic acid be named a-scorbic acid, and chemically -ascorbic acid, in honor of its activity against scurvy. The term's etymology is from Latin, "a-" meaning away, or off from, while -scorbic is from Medieval Latin "scorbuticus" (pertaining to scurvy), cognate with Old Norse "skyrbjugr", French "scorbut", Dutch "scheurbuik" and Low German "scharbock". Partly for this discovery,