Organic chemistry

Read the article: The effect of stereoelectronic control in proton removal from

4-t-butylcyclohexanone

J.C.S. Chem. Comm. 1974, 610-611

Explain what is a kinetic acidity value and what is a thermodynamic acidity value, how are each of these values measured and what value is measured in the article?

maintained (10:1) and sufficient D2O was used to ensure stereoelectronic controlf Although the ratio of axial: rapid deuteriation. The data were treated in a least equatorial hydrogens of 5.5 (Table) is somewhat less than squares analysis for log[H] removed vs time. Second- that predicted by Corey and Sneen in their original publicaorder rate constants (Table) were obtained by dividing the tion1 it is nevertheless still significant. pseudo first-order rate constants by the base concentration, Exactly why the 4,4-substituted cyclohexanones studied k2=kobs/[B]. by Bordwell 3 and his co-workers did not display a slower Under these conditions, cyclohexanone showed one rate rate of hydrogen-deuterium exchange relative to cycloof exchange for all of its -hydrogens, while 4-t-butylcyclo- hexanone is not entirely clear, although a number of conhexanone showed two rates (Table). tributing factors may be cited. However, in view of the In accordance with the results of the preparative experi- experimental results outlined lack of stereoelectronic control ment described earlier, the faster rate of 4-t-butylcyclo- does not appear to be one of them. hexanone was assigned to the axial -hydrogens while the slower rate was attributed to the equatorial -hydrogens. The results are again in good agreement with the theory of (Received, 19th March 1974; Com. 318.) 1 E. J. Corey and R. A. Sneen, J. Amer. Chem. Soc., 1956, 78, 6269. 2 (a) L. Velluz, J. Valls, and G. Nomine, Angew. Chem. Internat. Edn., 1965, 4, 181; (b) E. Toromanoff, Bull. Soc. chim. France, I962, 708, 1190 ; (c) W. G. Dauben, G. J. Fonken, and D. S. Noyce, J. Amer. Chem. Soc., 1956, 78, 2597. 3. F. G. Bordwell and R. G. Scamehorn, J. Amer. Chem. Soc., 1968, 90, 6749. 4 (a) C. Rappe and W. H. Sachs, Tetrahedron, 1968, 24, 6287; (b) J. A. Zoltewicz and P. E. Kandetzki, J. Amer. Chem. Soc., 1971, 93, 6562; (c) J. A. Zoltewicz and G. M. Dauffman, J. Org. Chem., 1969, 34, 1405; (d) C. Rappe and W. H. Sachs, ibid., 1967, 32, 3700, 4127