... (8) Cf. ref. 3, p. 282. (9) C. K. Ingold, Structure and Mechanism in Organic Chemistry, Cornel1 University Press, Ithaca, N. Y., 1953, p. 799. (10) (a) D. F. De Tar and M. N. Turetxky, J. Am. Chem. Soc., 77, 1745 (1955); (b) 78, 3925 (1956); (c) 78, 3928 (1956). ...