Results Measurement of Kinetic Isotope Effects. 1, l-Di-methylallene (1). 3, 3-Dideuterio-l, l- dimethylallene (l-dJ and 1, l-bis (trideuteriomethy1) dene (l-dd were prepared, and the kinetic isotope effects were measured by using competitive reaction techniques. Approximate 1: l mixtures of 1 and l-d2 and of 1 and l-d6 were prepared and the H2/D2 and H6/D6 ratios were determined by using mass spectral techniques (see Experimental ...