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COMMUNICATIONS TO THE EDITOR
The Diels-Alder adduct of anthracene and vinyl acetate2 was hydrolyzed to the secondary alcohol, oxidized to the ketone3 and converted with methylmagnesium iodide to the tertiary alcohol, m.p. 134-5". Calcd. for C17H160: C, 86.40; H,6.53. Found: C, 86.46; H , 6.84. This with thionyl Calcd. for C17chloride gave l a , m.p. 92-93'. H16C1: C, 50.14; H, 5.93. Found: C, 80.15; H, 6.27. Ib was obtained via exchange of some of the ketonic precursor of I a with deuterium oxide in boiling dioxane. ICwas made by the same route from anthracene-9,10-&, 1.79 atoms D per molecule, from reduction of a n t h r ~ n e . ~ N.m.r. spectra of Ia, Ib and the corresponding ketones were entirely consistent with these formulations and showed the deuterium compounds to be ca. 90% isotopically pure. Solvolysis of Ia in GOYo aqueous dioxane produced olefin and unrearranged tertiary alcohol. The solvolysis rate constants measured conductometrically are given in the table.
1701. 52
Acknowledgments.-The author appreciates the kind hospitality and assistance with this problem given him a t University College, London, and a t the &ole Nationale Superieure de Chimie a t XIontpellier, France, during the tenure of his sabbatical leave. The author is indebted to Dr. F. Winternitz for the microanalyses and to Dr. Brian Figgis for the n.m.r. spectra. CONTRIBUTION KO. 927 DEPARTMENT OF CHEMISTRY IXDIANA UNIVERSITY V. J. SHINER, JR. BLOOMISGTON, IXDIAXA RECEIVED MARCH11, 1960
A NEW SYNTHESIS OF ALIPHATIC AND AROMATIC THIOAMIDES FROM NITRILES
Sir:
Previously available methods for the preparation of thioamides from nitriles involve heating the nitrile in alcoholic solution in the presence of TABLE an alkali-metal hydrogen sulfide' or an ammonium2 FIRSTORDERRATE COSSTANTS SEC.-~) FOR SOLor substituted ammonium' sulfide. The formation VOLYSIS IN "GO'%" AQ ETHANOL AT 45 00" of aliphatic thioamides under these conditions reEach constant given is the average for one experiment of quires the use of high pressures in an a ~ t o c l a v e , ~ a number of integrated rate constants calculated for points taken over about three half lives. The point by point and the method is facile only with aromatic nitriles values drifted downward 1% or less during any run. containing electron-withdrawing substituents.' Compound k kdkD However, reduction can take place even under In 9 05 8 . 9 8 8.99" 9.14a*b mild conditions, and the formation of p-aminoIb 7.80 7.88 7.92" 1.14 1 0 01 thiobenzamide from p-nitrobenzonitrile is illusIC 9.12 9.2gavb 0 986 i 0 01 t r a t i ~ e . ~ The J use of a mixture of triethyla Taken after one additional recrystallization of previamine and pyridine as a catalyst for the direct ously used material. Run in a second solvent batch addition of hydrogen sulfide to nitriles is useful These figures show that occurrence of the p- only for aromatic nitriles and has little value for deuterium isotope effect depends not only on the the preparation of aliphatic thioamides.6 Thioposition but also on the orientation of the isotopic acids have found limited application as a source of bond. This result i s strikingly consistent z i t h the hydrogen sulfide for this conver~ion.'.~ We wish to report a new and general synthesis previous suggestion that hyperconjugative intramolecular transmzssion of electronic charge i s a n essential of thioamides from nitriles which utilizes thiofactor in causing P-deuterium substituted compounds acetamide as a source of hydrogen sulfide under to give slower carbonium ion type reactions than their acidic conditions. The thioamides are formed in protium analogs.6 Theory predicts that hyper- good yield in a high state of purity, and the method conjugation between the bridgehead deuterium is equally applicable to aliphatic nitriles, and atom in ICand the carbonium ion center resulting aromatic nitriles containing either electron-refrom solvolytic loss of the chloride ion would be leasing, electron-withdrawing or potentially relargely sterically prevented. In molecular orbital ducible substituents. One equivalent of the nitrile terms this is because the two orbitals which must is heated on a steam-bath for 15-30 minutes with overlap for hyperconjugation are mutually per- two equivalents of thioacetamide in dimethylpendicular. In valence-bond terms this is beYield, Nitrile Thioamide Yo M.P., O C . Rei. cause contributing forms having double bonds a t the bridgehead carbon atom would be too un- ~ - O Z N C ~ H I C N ~ - O Z S C B H I C S N H ~ 83 158.5-189.5 7 Z 148.6-149.5 6,9 stable to contribute significantly (Bredt's rule). p-CHaOCsHiCN ~ - C H ~ O C ~ H I C S N H 87 63 211-212 d. 10 CHz(CN)r CHz(CSNHz)t Thus with IC the normal isotope rate effect, ob- PI'C(CHz)rCN HzNCS(CHz)pCSITHs 7 8 178.5-179.5 d . 3.11.12 served with I b and other P-deuterio tertiary chloride^,^ is not found. Instead a very small (1) K. Kindler and F. Burghard, .4nn., 481, 201 (1923). "inverse" isotope effect, apparently due to an (2) S. Gabriel and P. Heymann, B e r . , 23, 157 (1890). (3) H . Erlenmeyer and K. Degen, Helu. Chim. Acta, 29, 1080 (1946). inductive interaction between the reaction center (4) C. Engler, Ann., 149, 297 (1869). and the isotopic bond, appears. I t zeould seem that ( 5 ) A. W. Hofmann, B e y . , 1, 194 (1868). for the first time the inductive and hyperconjugative ( G ) .4.E . S . Fairfull, J. L. Lowe and D. A. Peak, J . Chem. So
