The reaction of Grignard compounds with Schiff bases. II. The dimerization of Schiff bases in dependence on the substituents on the nitrogen and on the nature of the Grignard reagent

Abstract

cf. C.A. 51, 7319g. The reaction of PhCH:NR (I) with R'MgX (II) to form the dimer, (RNHCHPh)2 (III), rather than the adduct, PhCH(NHR)R' (IV), increases as the length of R and the branching of R' increase. I (0.2 mole) in 20 cc. dry Et2O added during 2 hrs. to 0.4 mole II in 100 cc. Et2O, the mixt. refluxed 4 hrs., decompd. with NaOH and ice, extd. with Et2O, fractionally distd., the distillate allowed to crystallize or the HCl salt formed in Et2O with dry HCl, and the residue from the distn. dissolved in HCl, freed from green side products with CCl4, the soln. made alk., and extd. with Et2O, and the ext. evapd. and allowed to crystallize, gave the following products (R, R', X, % yield of IV, and % yield of III given): Me, Me, I, 72, none; Me, Et, I, 67, trace; Me, Pr, Br, 59, 2; Me, Bu, Br, 74, trace; Me, iso-Pr, Br, 58, trace; Me, iso-Bu, Cl, 43, 14; Me, tert-Bu, Cl, none, 18; Et, Me, I, 49, none; Et, Et, I, 60, 5; Et, Pr, Br, 44, trace; Et, Bu, Br, 40, trace; Et, tert-Bu, Cl, none, 30; Bu, Pr, Br, 33, 16; Bu, Bu, Br, 47, trace; Bu, iso-Pr, Br, none, 56. The following compds. are new: 1-phenyl-1-methylaminopentane, b3 99-108 Deg (HCl salt, m. 142 Deg); 1-phenyl-1-methylaminobutane, b2 65-8 Deg (HCl salt, m. 217 Deg); 1-phenyl-1-butylaminobutane, b1 87-90 (HCl salt, m. 228 Deg); 1-phenyl-1-butylaminopentane, b2 122-7 Deg (HCl salt, m. 221.5 Deg); N,N'-dibutyl-1,2-diphenylethylenediamine (V), b0.5 158-70 Deg, nD76-8 (di-HCl salt, m. 185-220 Deg) (eutectic m.p. with dicyandiamide, 148-50 Deg; with salophen, 157-9 Deg). V and (MeNHCHPh)2, m. 135 Deg (di-HCl salt, m. 304 Deg, diacetyl deriv., m. 258-9 Deg), were prepd. for reference by adding (8 hrs.) 40 g. H2O to 0.5 mole I and 25 g. Al-Hg, in 1 l. Et2O, extg. after 40 hrs. with CHCl3, and evapg.