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In the presence of HCl, aromatics undergo chloromethylation. For reviews, see: Org. React., 1, 63 (1942); Russ. Chem. Rev., 46, 891 (1977). Caution! carcinogenic bis(chloromethyl) ether is formed in these reactions. In combination with Hydrobromic acid, A14475, the bromomethylation of aromatics has been effected: J. Org. Chem., 58, 1262 (1993). The same combination also N-bromomethylates phthalimide and other imides: Synlett, 933 (1994).• Reaction with dialkyl phosphites gives hydroxymethyl phosphonates, which, after O-protection, undergo the Horner-Wadsworth-Emmons reaction to give enol ethers. See, e.g.: Org. Synth. Coll., 7, 160 (1990).
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Formaldehyde monomer, generated by thermolysis, has been used for the ɑ-hydroxymethylation of dilithiated carboxylic acids. Dehydration of the products affords ɑ-alkyl acrylic acids: J. Org. Chem., 37, 1256 (1972). Monomeric formaldehyde can also be prepared as a THF solution by dehydration with p-Toluenesulfonic anhydride, L00160, and co-distillation of the monomer with the solvent: Synlett, 704 (1990). The use of anhydrous molecular formaldehyde for hydroxymethylation reactions has been discussed: Synlett, 227 (1990).•
For use in the preparation of di-t-butyl methylenemalonate, see Di-tert-butyl malonate, A12774. For the direct ɑ-methylenation of ketones, see N-Methylanilinium trifluoroacetate, A17781.• For use in preparation of Mannich bases, see: Org. Synth. Coll., 3, 305 (1955); 4, 281 (1963). For reviews, see: Org. React., 1, 303 (1942); Synthesis, 703 (1973); Tetrahedron, 46, 1791 (1990).
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Numerous examples of the use of aqueous formaldehyde are to be found in Organic Syntheses. See also Paraformaldehyde, A11313, and 1,3,5-Trioxane, A15639.
易燃性 (F)
腐蚀性 (C)
有毒 (T)
有害性 (Xn)
