De.,1948
NOTES
4263
A Novel Method for the Preparation of Dimethyl-
Conditions favoring I1 result in N-alkylation (IV), and lead ultimately to an amide R'CONHR, while ionization to yield I11 which would presumably be BY JOHNJ. RITTER favored in somewhat diluted sulfuric acid (92%), I n an attempt to effect the acetonitrile-diiso- leads to the ester of an imide sulfate V which on butene reaction' in cold concentrated sulfuric acid hydrolysis gives rise to the carbinol ROH. it has been observed that dimethylneopentylcar- CnsaarcAL LABORATORY binol is formed SLS the principal product. The NEWYORKUNNERSXTY SQUARE expected N-t-octylacetamide, which is produced in WASHINGTON RECEIVED JUNE11, 1948 good yield in aceticsulfuric acid solution, appears NEWYORK,N. Y. in much diminished amount. I n 92% sulfuric acid the yield of the carbinol reaches 70% of the calculated value without formation of hydrocar- Formation of Secondary Alcohols in the Free Radical Decomposition of Aldehydes bon polymer. However, diisobutene alone is completely polymerized by cold 92% sulfuric acid, BY FREDERICK F. RUST,FRANK H. SEUBOLD AND WILLIAM and the amide alone is simply dissolved under the E.VAUGHAN same conditions and may be recovered on subseAliphatic aldehydes are known' to decompose quent dilution. by a chain mechanism to hydrocarbon and carbon I n a typical experiment, a solution of 8.2 g., monoxide in accord with fhe equations 0.2 mole, of acetonitrile in 100 g. of 92% svlfuric acid was prepared by dropwise addition of the nii RCHO + R +RH f RCO (1) trile to the acid a t 0-5' with mechanical stimng. Diisobutene (22.4 g., 0.2 mole) was then added RLm R + co (21 dropwise a t 0-5" with continued stirring. The hydrocarbon dissolved promptly and substan- This transformation is accompanied by side reactially completely. Dilution of the reaction mix- tions which are incompletely understood. A brief ture by pouring on cracked ice separated an oil study of the decompositions of n-butyraldehyde layer which was removed, neutralized, dried over and n-heptaldehyde, sensitized by di-t-butyl peranhydrous potassium carbonate and distilled at oxide, has shown the formation of di-n-propylcarordinary pressure. Eighteen grams of dimethyl- binol and di-n-hexylcarbinol, respectively, to neopentylcarbinol, b. p. 145-147') d Z 3 u 5 4 0.8309. be significant secondary reactions. The implican% 1.4301, was obtained. A residue (5 g.) in tion is that the chain-carrying alkyl radical will the distilling flask solidified on cooling and was add to the carbon atom of the carbonyl group as identified as N-t-octylacetamide. A parallel ex- well as effect the more frequent removal of a hyperiment using 98% sulfuric acid yielded 60% of drogen atom (equation 1) the calculated amount of carbinol with a somewhat larger residue of amide. No hydrocarbon polymer could be detected in either case. The hydration of certain readily polymerizable olefins has been accomplished2 by the use of a solution of concentrated sulfuric acid in excess of I diethyl ether, in which the acid exists as the oxoR&HR + RCHO +RCHOHR RCO (4) nium sulfate. In the case at hand, the assumption that acetonitrile serves a similar purpose through Reaction (3) is, at least formally, the reverse of formation of the analogous nitrilium sulfate the well-demonstrated decomposition of the tR C r N H + S04H-3seems excluded as sulfuric alkoxy radicals2.a acid was used in high excess over acetonitrile (4.7 RR'R"C0- +RCOR' + R" (6) mole : 1 mole). It is suggested that the nitrileolefin-sulfuric acid reaction may proceed along and it is possible that both (3) and ( 5 ) are reversitwo competing routes determined by two modes of ble to some degree. In the case of the n-butyraldeionization (I1 and 111) of the alkyl sulfuric acid hyde decomposition, di-n-propylcarbinol is formed both in the liquid phase a t 115' and in the gas (I) fist formed a t 235'. In the latter case hexane-pre(11) R + + OSOIH- C,ROSOaH C , + H + (111) phase sumably from of propyl radiJk'CN (1) JRTN cals-is formed in only slightly lesser amount OWrR than the alcohol; whereas, in liquid phase the same hydrocarbon, although present, is R'NR (IV) R ' - L N H (V) of lesser importance. neopentylcarbinol
-
+
+
r?
(1) John J. Ritter and P. Paul Minieri, T H I ~ JOWRNAL, TO, 4046 (1948).
(2) 0. Aschan,"Naphthenverbindungen.Terpene und Campherarten,'' W. de Gruyter, Berlin, 1929, p. 107 (1) Ha8tzseL. En..64, 874 (1911).
(1) For summary, see Steade, "Atomic and Free Radical Reactions," Rdnhold Publishing Corp., New York, N. Y.,1948. (2) Milas and Surgenor, THIS JOURNAL, 68, 206, 648 (1948). (3) Ralcy, Rust 8nd Vsnghan. {bid., TO, 88
(lQ4S).
