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Dec. 5 , 1955THE ALKYLATION OF AMBIDENT ANIONS 6360 Preparation of the Schiff Base of 9-Anthraldehyde and Racemic 2-hinooctane.-One gram (0.008 mole) of racemic 2-aminooctane, 10 ml. of abs. ethanol and 1.65 g. (0.008 mole) of 9-anthraldehyde refluxed for ten minutes, allowed to come to room temperature and then placed in a refrigerator gave 2.3 g. of product, m.p. 60-62'. When recrystallized from 70% aqueous ethanol it yielded 2.1 g. (83% yield) of yellow crystals, m.p. 61-62'. Anal. Calcd. for QrHwN: C, 87.0; H, 4.41; N, 8.51. Found: C, 87.0; H, 4.37; N, 8.51.Catalvtic Reduction of (+ )a-Phenvlnitr0ethane.-A solution of 6.0 g. (0.40 mo1e)'of '( +) a-phenylnitroethane (b.p: 92' (2 mm.), nZoD 1.5216, az7D $2.80') in 30 ml. of glacial acetic acid was reduced at 4 atm. (1.0 g. of Adams platinum oxide). The theoretical amount of hydrogen was absorbed in 18 minutes and there was obtained 2.8 g. (58% yield) of (+)a-phenylettylamine, b.p. 71-72" (10 mm.), ? z Z o~ 1.5269, a z 7 D $6.50 . This gave the benzamide; recrystallized from absolute ethanol (m.p. 124-125') and then from petroleum ether (b.p. 60-70'); m.p. 124125'; lit. values: ( 7)benzamide deriv., m.p. 124.5-125.516; racemic benzamide of a-phenylethylamine has m.p. 120°.18The reaction of silver nitrite with alkyl halides proceeds via a transition state which has both S N 1 and S N~ character in proportions that vary gradually with the structure of the halide. The products of the reaction reflect this variation in character: The greater the carbonium contribution to the transition state the greater is the yield of nitrite ester and the smaller is the yield of nitroparaffin. This preference of a n anion (Nos-) for covalency formation a t the atom of higher electronegativity (oxygen) is general and forms the basis of the contrasting reactions of silver salts and alkali metal salts (e.g., AgCN and NaCN) with alkyl halides. Electrophilic attack by silver on the halogen of the alkyl halide greatly enhances the carbonium contribution to the transition state and this results in a preference for covalency formation to the most electronegative atom of the anion.Changes in the reaction medium and in the structure of the alkylating agent also may have a profound effect on the nature of the transition state and, when this happens, the nature of the products changes. The following generalization about the alkylation of anions possessing two different reactive positions (Le., ambident anions), which is fully applicable even when silver is absent, provides a simple rationale for the hitherto unsolved problem of carbon 2's. oxygen alkylation, oxygen ws. nitrogen alkylation. etc., in anions derived from acetoacetic ester, phenols, nitroparaffins, or-pyridone, acid amides, thioamides, etc. : The greater the S N 1 character of the transition state the greater is the preference for covalency formation with the atom of higher electronegativity and, conversely, the greater the Sx2 contribution to the transition state the greater the preference for bond formation to the atom of lower...

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A new type of substitution process at a saturated carbon atom is described. These reactions, which proceed via a chain sequence in which radical anions and free radicals are intermediates, are noteworthy for providing novel and powerful means of synthesis: they occur readily under mild conditions, they give excellent yields of pure products, and, in contrast to SN2 displacements, they are rather insensitive to steric hindrance. As a consequence, radical anion processes are especially valuable for the preparation of highly branched structures. Many inorganic and organic anions readily enter into these displacements and, indeed, amines are also effective. Systems which undergo substitution via this electron transfer mechanism include benzylic, cumylic, strictly aliphatic, and heterocyclic molecules. It is of interest that a number of groups which do not behave as leaving groups in S,2 displacements are readily displaced at room temperature from a saturated carbon atom uia the radical anion-free radical pathway, e.g., nitro, azide, sulfone, and ether groups.