The reaction process begins with the deprotonation of 2-nitropropane at the α carbon to form a nitronate. This compound then initiates an SN2 reaction to displace the benzyl halide. Unlike in the nitroaldol reaction, where the deprotonated carbon of the nitroalkyl group is the nucleophilic atom, it is instead an oxygen of the nitro itself that attacks the benzylic carbon.[4] The O-benzyl structure then undergoes a pericyclic reaction to produce a benzaldehyde, with dimethyloxime as a byproduct.
Although originally developed for benzyl compounds, the reaction also works for allyl halides, giving the respective α,β-enones and enals.[5]
References
^Hassner, Alfred; Namboothiri, Irishi (2012). "Hass–Bender carbonyl synthesis". Organic Syntheses Based on Name Reactions: A Practical Guide to 750 Transformations. Elsevier. pp. 203–204. ISBN978-0-08-096630-4.
^Hass, Henry B.; Bender, Myron L. (1949). "The Reaction of Benzyl Halides with the Sodium Salt of 2-Nitropropane. A General Synthesis of Substituted Benzaldehydes". J. Am. Chem. Soc. 71 (5): 1767–1769. doi:10.1021/ja01173a066.
^Bersohn, Malcolm (1961). "C versus O Alkylation in the Case of a Stable Cation". J. Am. Chem. Soc. 83 (9): 2136–2138. doi:10.1021/ja01470a022.
^Montavon, M.; Lindlar, H.; Marbet, R.; Rüegg, R.; Ryser, G.; Saucy, G.; Zeller, P.; Isler, O. (1957). "Synthesen in der Carotinoid-Reihe. 11. Mitteilung. α,β-Ungesättigte Carbonylverbindungen aus Allylhalogeniden mittels Nitroparaffinen". Helv. Chim. Acta. 40 (5): 1250–1256. doi:10.1002/hlca.19570400516.
