NOTES
3145
TABLE I PROPERTIES O F PHENYLPYRIDINES Iliciie I ioprviie t,O-Peritadienc 2,3-Dimethylhutadic11c 5-~Ic-l,,';-peiitadieiit. Pyridinic product 2-Ph-4-mrthyl2-Ph-6-methyl2-Ph-4,5-dimethyl%-Ph-4,6-dimethyln 1 ,5993 1,6103 1.6059 1.6062 (35') B.p., " C . (mm.) 110-1 t < i( 3 ) 117-120 (4) 146-1B0 (6) im-134 (4) f Obsd. 185 187 186-188 129--130 202-203 Picrate, m . p . , 186-187' Lit. 162" 135' ..... L. Musajo and M. Colonna, Gnza. chim. itnl., 62, 894 (1932). R. L. Frank and R. P. Seven, THISJ O U R N A I , 71, 2C20 (1019). R. L. Frank and P. \\'. Meikle, ibcd., 72, 4184 (1950). T'HYSICAI.
1
~
TABLE I1 REACTION CONDITIONS, MATERIAL BALANCE A N D YIELDS .4ct ivnted Alumina, A1-0501, Cat a1yst Reactants, Ilerizonitrile
+
Diene
'r, DC.
Catalyst, cc.
400 78 105 78 397 92 398 R7.j 2.3-Dimethyl-1,3-butadiene 395 78 a Defined as nioles/hr./100 cc. catalyst. 1,3-Butadiene Isoprene 1,3-Pentadiene 2-Methvl-l,3-~t=titadiene
Mole ratlu
Contact time. sec.
(DE21
3.9 4.5 4.2 3 2 4.1
1 2 1 0 1.0 1 .o 1 0
the light of the catalyzed reaction mechanism discussed in an earlier paper.3 The yields of phenylpyridines calculated on the nitrile conversions (Table 11) undoubtedly can be improved with further study. Thus, using a chromia-alumina catalyst, %phenylpyridine has been obtained in 60 mole yo yield4 as compared to 27 mole % in this work. This reaction offers a ready method for the synthesis of these phenylpyridines in small amounts. In addition t o simplicity, the method is specific for the desired product, a direct contrast to the more recognized procedures in which mixtures of pyridines are formed. Acknowledgment.-This work was made possible by a Frederick Gardner Cottrell Grant from the Research Corporation. The authors wish to thank the Phillips Petroleum Company for the kind gift of chemicals. DEPARTMEST O F CHEMISTRY RENSSELAER POLYTECHTIC INSTITUTE T R O Y SEW , YORK
T h e Preparation and Properties of 2-Chloro-2'fluorodiethyl Sulfide' n u 1 4 . S. KHARASCH, S. ~VEINHOCSEAND E. 1.. SENSES RECEIVED SOVEMBER 29, 1954
As part of a program to discover new methods for the preparation of organic fluorine compounds, 2-chloro-2'-fluorodiethyl sulfide has been prepared and its properties investigated. Attempts have been made by some British investigators to prepare the fluorine analogs of "mustard gas" by the action of thionyl fluoride and anhydrous hydrogen fluoride on thiodiglycol. T h e experiments were conducted in metal containers, with and without solvents, a t high and low temperatures. KO volatile fluorine compounds were obtained. (1) This work was done in 19-12 for t h e Office OF Scientific Research and Development under Contract Xo O R h l s r - 3 0 4 w i t h t h e TJnivcrsily of Chicago.
Material balance Total input, Recov. g. P.
85.8 65.4 109.6 109.2 132 5
85.0 65.1 108.,5 107.1 128.1
L7itrile converiiirn ( 4 1 , mole !{
Pyridinic product Yielcl, Sliacenilc time calcd. yieI-drogen fluoride. The 48 g. of colorless distillate was washed with water, dried over anhydrous sodium sulfate, and distilled under a pressure of 20 mm. The fraction boiling below 100" (25 g.) was refractionated a t 30 mm. pressure. T r r o fractions were obtained. T h e first (b.p. 62.5 to 91.5') is probably a mixture of difluorodiethyl sulfide and 2-fluoro2'-clilorodietliyl sulfide. Ann/. Calcd. for CaHaSFz: F, 30.1. Found: F, 18.0. Calcd. for C4H&FCl: CI, 24.9. Found: C1, 13.0. The higher boiling fraction distilled sharply between 91 .,7' and 92.5' (30 mm.). It weighed 16 g., a yield of 227,, c E z 0 ~ o 1.228, Z*'D 1.4852. d n n l . Calcd. for CdHsSFCI: F , 13.3; C1, 24.9; S, 22.4. Found: F , 13.8; C1, 24.4; S . 22.0. T h e molecular refractivity calculated from t h e density and refractive index is 33.1; the value calculated from the sum of the atomic refractivities is 33.4. DEPARTMEST OF CHEMISTRY UNIVERSITY OF CHICAGO CHICAGO d i , ILLIL-OIS
Acid-catalyzed Hydrolysis of Acetal and Chloroacetal BY ~ I A U R I Chi. E KREEVOY A N D ROBERTW. TAFT,J R . RECEIVED J A N U A R Y 22, 1955
In the course of a study of the relative rates of acetal and ketal hydrolysis,2 the acid dependence and solvent isotope dependence of the rate has been investigated. The results provide additional support for the mechanism of O'Gorman and Lucas.".? This present work also extends the range of this mechanism, shown in equations 1-3, t o a 50% dioxane-water mixture. ( 1 ) T h e work herein reported was carried out on Project NR055-328 between t h e Office of Naval Research and t h e Pennsylvania State Llniversity. 12) hl. 31.Kreevoy and R . W. T a i t , J r . , THISJOURNAL, forthcoming. (3) J. 31. O'Gorman and 14. J. Lucas. ibid., 73, 5489 (1950). (4) C. K. Ingold, "Structure and Mechanism in Organic Chernistry," Cornell LJniversity Press, I t h a c a , X. Y.,1953, p. 334.
Previously reported evidence supporting this there is no racemization a t the ; ('2) the reaction exhibits speon catalysis in water'; (3) the second-order rate constant is larger b y a factor of three in deuterated water8; (4) the rate is a linear function of Isowith unit slope, indicating that no water molecules are firmly bound in the transition The present work shows that the rate of hydrolysis of chloroacetal, like t h a t of methylalg and ethyla1,"has the indicated aciddependence, t h a t the hydrolysis of acetal in 50% aqueous dioxane is likewise faster by a factor of three when deuterated water is used, and t h a t acetal hydrolysis in SO7c aqueous dioxane is catalyzed only very slightly if a t all by inolecular formic acid. Results 110 Dependence.-The acid dependence of the rate of hydrolysis of chloroacetal (in a solvent containing 4yodioxane) is shown in Table I. The last column of this table is expected by theory12,13 to be approximately constant. A s with methylalg and ethylalll the rates in the more concentrated hydrochloric acid solutions are somewhat higher than predicted b y theory. IYith methylal this deviation was shown to be caused b y a specific effect of chloride ion on the activity of the substrate,gband the same is very likely true in the present case. Four concentrations of perchloric acid, sulfuric acid, and the most dilute hydrochloric acid give constant values of (log kl IIo)of acceptable precision. Solvent Isotope Effect and General Acid Catalysis.-The second-order rate constant for the hydronium ion catalyzed hydrolysis of acetal in
