a 9570 ethanol solution of it with a few crystals of the latter crystalline modification. Treatment of Nitrile VI1 with Two Equivalents of Potassium Amide a n d One of Benzyl Chloride.-To a stirred solution of 0.2 mole of potassium amide in 300 ml. of liquid m"m12 was added 37.3 g. (0.1 mole) of 2,3,3,4-tetraplienylbutyronitrile ( V I I ) . The resulting green solution was stirred for 15 minutes, and 12.6 g. (0.1 mole) of benzyl chloride in a little ether then was added. T h e first few nil. of the hilide solution produced a purple color which persisted until a few seconds after all of t h e halide had beeii added. After stirring for 5 minutes, excess (15 g . ) ammonium chloride was added and the ammonia was evaporated as a n equal volume of ether was added. T h e resulting ethereal suspension was shaken with water. T h e aqueous layer was extracted with ether containing some ethyl acetate and the extracts were combined with the ethereal l3yer. T h e ethereal ethyl acetate solution was dried and t h e solvents removed. T h e residue was taken u p in hot benzene and about 800 ml. of petroleum ether (b.p. 30-60') was added. T h e solution was cooled in an ice-bath t o precipit a t e slowly 30.7 g. (837,) of recovered nitrile VII, n1.p. 136138'. T h e remaining liquors were concentrated t o a small volume on the steam-bath and hot ethanol was added. Cooling produced 6.9 g. (77%) of stilbene, m.p. 110-112°, slightly contaminated with the nitrile. Recrystallization of the hydrocarbon from ethanol raised the melting point t o 119-121'. Admixture with an authentic sample of stilbene, m.p. 122-124', did not depress t h e melting point. Independent Synthesis of @-Benzyl Derivative VI1.2,3,3-Triphenylacrylonitrilewas prepared by the condensation of phenylacetonitrile with benzophenone in the presence of sodium amide.'* To a stirred ethereal solution of benzylmagnesium chloride prepared from 0.22 mole each of magnesium turnings and benzyl chloride was added 48.25 g. (0.172 mole) of 2,3,3-triphenylacrylonitrile. After stirring for 5 hours the reaction mixture was poured into iced hydrochloric acid. T h e ethereal layer was separated from the aqueous mixture containing the insoluble hydrochloride as imine I X , and dried for 12 hours over magnesium sulfate. During this time more of t h e imine hydrochloride precipitated. T h e ethereal solution was filtered and the solvent removed. Recrystallization of t h e residue from ethanol produced 2.8 g. (4.4%) of 2,3,3,4-tetraphenylbutyronitrile ( V I I ) , n1.p. 137-138'. Admixture of this product with t h e benzylation product ( m . p . 138-139') of the dicarbanion of nitrile 111 did not depress the melting point, and their infrared spectra were superimposable. The imine salt was converted t o the corresponding ketone by boiling for one hour with 12 31 hydrochloric acid. T h e water was decanted and the residue recrystallized from ethanol and acetone t o give 22 g . (317,) of 1,3,4,4-tetraphetiylbut-3-ene-2-one ( X V I ) , m.p. 139-144', yellow needles. Recrystallization from ethanol raised the melting point t o 149-150'. .4nnl. Calcd. for C?sH?20:C, 89.80; H , 5.9.). Found: C, 89.83; H, 6.06.
[CONTRIBUTION FROM
THE
T h e infrared spectrum of the imine hydrochloride showetl p . i These bands were absent in ketone XVI which had a M ell defined carbonyl band a t 5.9 @ . I 3 Benzylation of the Monocarbanion IV to form a-Benzyl Derivative XII1.-To a stirred solution of 0.05 mole of POtassium amide in 300 ml. of liquid ammonia was added 14.2 g. (0.05 mole) of solid 2,3,3-triphenylpropionitrile(111) by means of a powder funnel. T h e resulting light green solution of monocarbanion I\' was stirred for 15 minutes, and 6.3 g. (0.05 mole) of benzyl chloride in an equal volume of ether then was added. T h e reaction mixture was dllowcd t o stir until the ammonia had evaporated completely. Tt'ater was added and the product collected on a buchner funnel. T h e filter cake was washed with water, dried and washed with a little petroleum ether (b.p. 30-60'). There was obtained 18.14 g. (97%) of 2-benzyl-2,3,3-triplienylpropionitrile ( X I I I ) , m.p. 182-185'. Two recrystallizations from absolute ethanol raised the melting point t o 185.5187". T h e infrared spectrum of this compound showed band a t 4.45 p attributable to the cyanide group, b u t an absence of absorption about 6 p , a region in which imines have been observed t o absorb.7 This spectrum differed from t h a t of 2,3,3,4-tetrapIieiiyIbut) ronitrile ( V I I ) in t h e fingerpriut region. Anal. Calcd. for C?aI-123S:C , 90.04; €1, 6.21; N , 3.75. Found: C, 90.14; H, 6.33; N, 3.88. Treatment of Dicarbanion V with Methylene Chloride .To a stirred solution of 0.2 mole of potassium amide in 500 i d . of liquid ammonia was added 28.3 g. (0.1 mole) of 2,3,3triphenylpropionitrile (111). T h e resulting red solution of dicarbanion V was stirred for 10 minutes, and 10.2 g. (0.1% mole) of methylene chloride in 50 ml. of ether then was added. After stirring for 1.5 hours (red color still present), the ammonia was replaced with ether. TVater was added and the ethereal layer mashed with 6 df hydrochloric acid, followed by water. T h e ethereal solution was dried and the solvent removed. T h e residue was taken u p in hot rnethm o l , and then treated with Norite t o give on cooling 18.7 g. (64%) of apparently 1,2,2-tripIienylcyclopropyl cyanide ( X V I I ) , m.p. 118-121'. Five recrystallizations froni methm o l raised the melting point t o 131.5-132.5'. Aizal. Calcd. for C2?HliS: C , 89.46; H , 5.80; N, 4.74; mol. mt., 295. Found: C, 89.69;H, 5.80; N , 1.73; mol. wt., 299, 286, 278, 291. T h e infrared spectrum of the nitrile gave the following bands: 3.27, 4.45, 6.25, 6.30, 6.68, 6.88, 8 . E , 9.26, 9.70, 9.85, 10.17, 12.68, 13.29, 14.15, 14.37 p . T h e nuclear magnetic resonance spectrum of a saturated carboil disulfide solution of XVII indicated t h e presence of both aromatic and aliphatic hydrogens in the molecule." T h e aromatic absorption was much stronger and could be resolved into four distinct bands. DURHAM, S.C.
a broad band at 3.55 and a sharp band a t 6.05
(13) See ref. 7 , p. 114. (14) W e are indebted to G . S . Paulett for t h e interpretation of the nuclear magnetic resonance spectrum which was determined in t h i 1.aboratory o n a Varian h7.\f,R, Spectrometer, model V-k:IOOB.
WALKER 1,ADORATORY O F
THE
R E S S S E L A El'OLYrECIINIC R TNSTITU.I.E
Derivatives of Aromatic Sulfinic Acids. 111. Evidence for the Hydrogen Dichloride Ion from Epimerization Reactions' BY HARRY F. HERBRANDSON A N D RICHARD T. DICKERSON, JR. R E C E I V E.IUCUST D 11. 1958 .kymnietric sulfinic esters, XrS(O)OR, epimerize at the sulfur atom when treated in nitrobenzene with hydrogen clilixide and chloride ions as co-catalysts. The mechanism of the reaction is discussed, and tile kinetics is interpreted as giving value I< -CI % of 500-1000 1. inole-' for the association constant of the hydrogen dichloride ion in nitrobenzene a t 23" : Cl CIHC1-.
+
The reactions of alkyl sulfites and alkyl arenesulfinates with thionyl chloride are very similar,2but
kinetic studies are complicated by the ease of hydrolysis of the thionyl chloride. Since these es-
(1) This work was supported in p a r t b y t h e Office of Naval Researrh and i n p a r t by a grant from t h e R . €' I . Research Fund.
J O C J R N A I . , 78,
( 2 ) H . F. Herbrandson, R . 'I-. Dickerson, J r , and J W'tinslein, '1x1s 257G (1950).
HYUROGEX DICHLORIDE IOK FROM EPIMFRIZATIOITS
Aug 5 , 1959
r
I
I
1 10.0
10.0
'ci
e
e
6.0
8.0 % &- 6 . 0
& 4.0
& 4.0
'ti
8.0
3
5
4103
3
X
X
2.0
2.0 0
0 0.010 0,015 [HCllo. Fig. 1.-Epimerization of I-menthyl I-p-methoxybenzenesulfitiate with tetraethylammonium chloride as co-catalyst (in mole/l.): 0, 0.01784; 8,0.00892; aj, 0.00540. e , 0.00270; 8,0.00108; dashed curves from eq. 1 , solid curves from eq. 8 .
0
0.005
ters serve as mild alkoxylating agents, an alkoxide acceptor other than thionyl chloride was sought which would simplify kinetic studies. Anhydrous hydrogen chloride, in nitrobenzene, has been found to serve this purpose very well. Optically active 2-menthyl esters of arenesulfinic acids (Ia, b) epimerize a t the sulfur in the presence of low concentrations (0.001-0.02 molar) of hydrogen chloride and tetraethylammonium chloride.
0
0.005
0,010
0.015
[Cl-lo. Fig. 2.-Epimerization of l-menthyl I-P-methox).betizenesulfinate with hydrogen chloride as co-catalyst (in xnole/l.): 0,0.01816; a,0,00905; aj,0.00514; e, 0.00325); @, 0.00218; dashed curves from eq. 1; solid ctirves from eq. 8.
version of the liquid ester to its crystalline epimer and permits its recovery in iO-90yo yields.
Kinetic Results The epimerization of I-menthyl I-arenesulfinates, catalyzed by tetraethylammonium chloride and hydrogen chloride in nitrobenzene a t 25", was followed polarimetrically. Three esters which behaved similarly were used, namely, l-menthyl 1benzenesulfinate, 1-menthyl I-P-toluenesulfinate and I-menthyl 1-p-methoxybenzenesulfinate. The ratesof-change in rotation were strictly first order for more than 2-3 half-lives, with the pseudo-firstorder rate constant increasing only 2Yo for a 13-fold increase in initial ester concentration. TetraethylThe conclusion that the reaction is an epimerization3 ammonium chloride alone had no effect on the esis a consequence of a number of observations. Con- ters, nor did hydrogen chloride, which in nitroben, ~ any effect a t centration of the combined nitrobenzene solutions zene is essentially ~ n - i o n i z e dhave from a number of completed kinetic experiments concentrations below about 0.01 molar. At higher gave, after recrystallization, 67% of the initially concentrations, hydrogen chloride led to a change used 1-menthyl 1-p-toluenesulfinate. Thus, even in rotation that was dependent on the hydrogen though the reaction had ceased, as observed polari- chloride concentration approximately to the 2.5 metrically, unreacted levorotatory ester remained. power. Since this effect was observed only a t relaThis clearly resulted from the establishment of an tively high concentrations of hydrogen chloride, it equilibrium involving the ester, as the kinetics of was not troublesome in most of the kinetic runs, the reaction (pseudo-first-order in ester) demon- and because the magnitude of the effect was known it could be corrected for in runs to which it did co11strated no consumption of the catalysts, Further evidence for an equilibrium between tributee6 A t a constant concentration of one of the cataepimers resulted from the use of the catalysts on a preparative scale. The usual preparation of 1- lysts, an increase in the concentration of the comenthyl arenesulfinates from the arenesulfinyl catalyst led to an increase in the pseudo-first-order chloride and 1-menthol, in the presence of a base rate constant that indicated a diminishing effectivesuch as pyridine or potassium carbonate, leads to a ness of the catalysts a t higher concentrations (Figs. mixture of the two epimers from which the less solu- 1 and 2 ) . Typical data are recorded in Table I ; ble, crystalline one can be isolated in about 30y0 the pseudo-first-order rate constant, k ' , was obC yield.? Addition of gaseous hydrogen chloride or tained from the expression ln(a2 - cy1) = k't hydrogen chloride and tetraethylammonium chlo- for the rate of epimerization of /-menthyl I-9-rnethride to the remaining liquid ester causes rapid con- oxybenzenesulfinate.
+
(3) The more soluble, lower-melting epimers of the esters used in this study have never been purified completely. However, Phillips4 has demonstrated that 1-menthyl d- f dl-9-toluenesulfinate isomerizes on long standing t o I-menthyl 1dl-p-toluenesulfinate. Recently we have obtained pure both epimers of a sulfinic ester These will be the subject of a later communication. (4) H Phillips, J Chcm. Soc , 117, 25.52 (1925).
+
( 5 ) M . Hlasko and E.hlichalski, Rors. Chenz., 6 , 534 (1926); C.A . , 21, 35230 (1827); D.M . Murray-Rust, II. J . Hadow and H . Hartley, J. Chem. Soc., 215 (1931). (6) The correction was made by subtracting from the k ' obtained with the combined catalysts the value of k' obtained with hydrogen chloride as the sole catalyst. The values of k ' were chosen a t equal concentrations of available hydrogen chloride, [HCI] (see below),
TAULE I EPIMERIZATION O F l-&’IENT€XYL l-p-METHOXI’BENZESESULFINATE IN XITROBEKZEXE AT 25.00 f- 0.05’ Initial ester, mole/].
Total HCI, mole/l.
0.0349
0.01816 ,01816
0319
0349 03-19 0349 0358
0358 ,0358 0358 ,0358 ,0372 ,0372 0372
,00514 .00514
,00108 . 00870
00514
00540 00892 01 784 00540 ollXn2 . 01 x 4 00,540 00892 ,01784
,00511
,00514 , O( 1 71s 007118
,00218 ,00322 00.322
,00322
,
,00270 on892 ,131784 no108 00270 , no540 ,00892 , 0 1784
0372
,0385
0.00108
,01816 ,01816 ,01816 .00905 on903 ,00905 ,00905 no905
,0372 0385 O:H5 . 0:385 0385 wl83 0349 , 0368 03 78 0349
Tetraethylammonium chloride. mole/l.
,01816
00905 . no514
0
00540
,
0 0 0 0,0357
k’ X 10.1, sec.
0.947 2.33 4.58 (i. 67 9.83
0,643 1, .i3u 3.13 3.90 1.97 0.502 1.005 2 33 2 ti5 2.185 1.275 1.48:1 1.422 1 770 1 878 3.000
0,432
,096 ,067 0
Discussion The epimerization reaction may be treated kinetically as approaching the equilibrium concentration of epimers by a simple first-order reaction, with the observed rate contant, k’, being the sum of the rate constants for the forward and reverse reactions, k’f k‘,.’ This pseudo-first-order rate constant contains the specific rate constant for the reaction, k , and the concentrations of hydrogen chloride and chloride ion, which within any single run are invariant.
+
In (u, -
0 1 ~ )=
(kf’
+ kr’) t + C
=
k’t
+C= +C
k[HCl][Cl-]t
(1)
However, the ineffectiveness of added catalyst a t higher concentrations suggests that the hydrogen chloride and chloride ion may be reacting to give an inert species, the hydrogen dichloride anion, HClt comparable to HF2- (the bifluoride or hydrogen difluoride ion) but presumably less stable. Other evidence besides that already citedgfor the interaction of hydrogen chloride and chloride ions has been summarized recently by Sharp.g In addition should be mentioned the early work by Hunter’” and the observation by Pinner,” who first synthesized imino ethers, that the salts of these as first formed contained two moles of hydrogen chloride and that upon standing one mole was slowly lost. Similarly, it appears that dicyclopentadien(7) L. P . H a m m e t t , “Physical Organic Chemistry,” McGraw-Hili Buuk Co., Inc., New York, N. Y., 1940, p. 102. ( 8 ) H. F. Herbrandson, R. T. Dickerson, Jr., and J. Weinstrin. THIS I O I I K N A L , 7 6 , 1046 (1954). (Y3 D. W. A. Sharp, J. Chcm. Suc., 2558 (19583. (10) W . H. H u u t r r and G. D. Byrkit. ‘I‘HLS J O I J ~ N A L . ,64. I Y - 1 8 (I Y32). (11) A . Pinner, Hdr., 16,3.53, 1654 (1883).
ylrheniuni hydride gives a salt that contains the hydrogen dichloride anion.12 Tetrapbenylarsoniuni hydrogen dichloride also has been reported.13 Recently, evidence on the conductivity of the hydrogen dichloride ion has been published14 as has evidence for the symmetry of the hydrogen bond in this anion.I5 The postulation of the intervention of the hydrogen dichloride anion in the epimerization reaction would be supported if it were to permit the calculation of the actual concentrations of the free hydrogen chloride and chloride ion which serve to catalyze the epimerization reaction. Assuming an equilibriiim constant
can be written for the association, knowledge of the correct value of K would permit determination of the product [HCI][Cl-1. This plotted DS. k’ should give a straight line of slope k. The constant K has been determined by a series of successive approximations from the data on the epimerization of the three esters. The hydrogen chloride, [HCl], and chloride ion, [CI-1, available for catalysis of the reaction can be expressed in terms of the stoichiometric concentrations of hydrogen chloride and tetraethylammonium chloride, [HClIoand [Cl-lo, respectively, with a = [HCI]o[Cl-lo and b = [HCl]” [Cl-I,, and the equilibrium constant K from equation 2 , neglecting extraneous roots.
+
[HCl] =
Ka - 1
+ d K 2 0 2+ 2Kb + 1 ~~
2K
The product of these concentrations for use in equation 1 is [HCI][Cl-] =
Kb
+ 1 - d K W + 2Kb + 1 2K2
These equations are most easily applied when [HClIo = [C1-l0, i.e., a = 0, in which case they reduce to equations 6 and 7.
+
-1 d-__m [HCI] = [Cl-] = ___- 2K
From equation 6 by use of various assumed values of K and interpolated values of [HCIIo = (12) IvI.L. H. Green, L. P r a t t a n d G. Wilkinson, J . Chem. SOC.,3916 (1958). (13) F. Blicke and E. Monroe, THISJOURNAI., 67, 720 (1935). (14) E. D. Hughes, C. K. Ingold, S. P a t a i and Y . Pucker, J . T h e m . SOL.,1206 (1957). (15) J. C . Waddington, ibid., 1708 (1958). (16) T h e assumption h a s been made t h a t all of t h e chloride ion not bound a s hydrogen dichloride is available t o catalyze t h e reaction. Actually, some is present a s free chloride ions and some a s undissociated tetraethylammonium chloride.” To a first approximation a t t h e l o w concentrations used, most of t h e quaternary salt is dissociated. Furthermore, it has been suggested t h a t ions in ion pairs may be almost a s reactive a s free ions.’* Work is being done with a related system t o determine t h e effect of t h e undissociated quaternary chloride. (17) C. K. Witschonke and C . A . Kraus, Tars J O U R N A L , 69, 2472 (1947). (18) L. P. H a m m e t t , “Physical Organic Chemistry.” ,McCrak Hill H w k Cotnpauy, X c w York, N. Y . ,1940, p. 5 2 .
Aug. 5, 19.59
4.0
4 105
HSDROGEN DICHLORIDE IONFROM EPIMGRILA I'IONS
I-
' I
10.0
i 8.0
I
c; 3.0
x N
3.
2
x
I
u'
2.0
%
-r2
5: 1.0
5
r4!
0Y 0
0.002
0.004 0.006 0.008 [HClJ = [Cl-1.
I 0.012
0.010
[Cl-1, from Figs. 1 and 2, approach to a linear relationship for d p vs. [HCl] with K = 500 to 1000 gave a first approximation (Fig. 3). These values, as well as others were then used in equation 5, with all of the experimental data for each ester, as in Fig. 4,in an attempt to improve the approximation of K . The value K = 1000 seemed to fit as well as K = 500. Finally, using the third-order rate constant obtained from Fig. 4 and the calculated concentrations of available hydrogen chloride and chloride ions from equations 3 and 4,curves were constructed (Figs. 1 and 2) which should have corresponded to the experimentally observed results. The best fit was obtained using K = 500. The two calculated curves are of identical form because of the symmetry of the expression which is used, but the experimental data deviate non-symmetrically from these curves. It must be concluded that increments in [HClIo and [C1-l0 are not equivalent in their effects on the rate. If the hydrogen dichloride ion could serve in place of the chloride ion as a co-catalyst with hydrogen chloride, then the curvature of the k' vs. [HCI] plot should be less than that of the k' vs. [Cl-] plot, since as chloride ion is consumed by added hydrogen chloride, its role can be filled by the hydrogen dichloride ion. The pseudo-first-order rate constant then would not be k' = k [HCl] [Cl-] but rather k' = klHCl] [Cl-] k*[HCl] [HCL-] with k" the sum of the rate constants for forward and reverse reactions for the hydrogen dichloridecatalyzed reactions. Treatment of this in a manner similar to that accorded equation 1 yields equation S
+
=
k
+ 1 - -\/K2a2 + 2Kb + 1 + 2K2 ( K b + 1 - d K Z a 2+ 2Kb +T)2 k* 2 K * ( - K a - 1 + d K 2 a z+ 2Kb + 1 )
4.0
2.0
Fig. 3-Equations 1 and 6 with various values for K: 0, 50; e, zoo; a,500; a, 1000; 8,10,ooo.
k'
6.0
.,
..
0
0
4
8 12 16 20 24
[HClI X [Cl-I X loe. Fig. 4.-Equations 1 and 5 with K = 500.
participation by the hydrogen dichloride anion may in fact occur. Kinetically the catalysis which we have interpreted as being by hydrogen chloride and chloride ion could as well be by the hydrogen dichloride ion alone. On other grounds this alternative appears TABLE I1 RATE CONSTANTS FOR THE EPIYERIZATION OF I-MENTHYL BY HYDROGEN CHLORIDE,CHLORIDE I-ARENESULFINATES IONSAND HYDROGEN DICHLORIDE IONSI N XITROBENZEXE AT
25.00
=!c
0.05", ASSUMINGK = 500
1./MOLE R a t e constants, 1 . 2 mole-? sec. -1 C1- catalysis HCli- catalysis
I-Menthyl ester
28.2 28.0 35.0
1-Benzenesulfinate I-p-Toluenesulfinate
I-p-Methoxybenzenesulfiuate
1.51 I . 50
1.87
to be rather unlikely and, is rendered improbable kinetically by the difficulty of fitting into any simple scheme based upon this the term which we attribute to hydrogen chloride and hydrogen dichloride catalysis. A reversible reaction of the ester with the two catalysts to give the sulfinyl chloride and I-menthol via a transition state approximating I1 may account for the observations. 0
t
Ar-+OR
0
+ 11-CI + C1-
ki
k- I
t
f i r -S I
-+ llOR -t C1.-
c1
Kb
~
(8)
By successive approximations a value of k/k* = 18.7 was found to be fairly satisfactory for all three esters. The values of the rate constants determined from this equation with K = 500 are listed in Table I1 and theoretical curves based on these values for 1-menthyl 2-p-methoxybenzenesulfinate are included in Figs. 1 and 2. The better agreement with the observed"experimenta1points sugcests that
4
J
k- z
0
&I%-
0
T
11
I' 0 1 HE E D I T O R
If tlie asyniiiietric sulfur uiitlergoes a displacenittit reaction by inversion and a re-esterification in the same manner, no epimerization should occur. However, if reaction through I1 is rate determining, a subsequent rapid interchange of chloride ions by the sulfinyl chloride with racemization a t the sulfur could account for the epimerization.
I
+
'.'
CI -
I f this picture of the reactioii is correct, equation 1 must be replaced by equation
9.
Here the specific rate coiistants for the forward and reverse reactions of the simple epimerization equation are diminished by that fraction of the racemized sulfinyl chloride that reverts to the epimeric ester from which i t was formed. -Although the accelerating effect of the p-methoxy1 on the rate is relatively small, it suggests an increase in positive charge on the sulfur in the transition state.
Experimental l9 i-Menthyl l-Benzenesulfinate.~-Benzeiiesulfiriyl from 34.7 g. (0.244 mole) of benzeiiesulfinic acid iii mi equal v ~ l ~ nofi edr>-ether was c:tuseti to react with 38.0 g . (0.243 niole) of ~-lTieIithCJ1in 20 ml. of dry pyridine. lieino\xl of the etlier in oncuo 3fter washing with water, dilute hydriichloric acid, twice again with water, and drying over sodium sulfate gave an almost colorless oil. The higher-melting epimer was separated froin the mixture by careful cooling, with solid carbon dioxide, of a solution in three vnlumes of methanol. The colorless crystals, 20 g. (0.071 mole, 297;), of /-menthyl I-benzeiiesulfinate were collected, w-aslicd with cnld, aqueous methanol, and recrystallized from methanol. .inother recrystallization from methanol aiid three froin pentane gave a product of m . p . 49-51', i a j Z 5 D -205.5" ( G 2.0 in acetone), [cx]'~D -210.4' ( 6 1.1 in nitrobeiizene). .1viiI. Colcci. frir ClJl,102S: C . f%.,?l; I€, 8.62; S,11.18. 1;ouiitl: C , 08.6:j; I%, 8.80; S, 11.25. ~~
, 171) .4tialyse., ~ v e r eperlorinerl
b y C1:Lrk Micruanalytic~*l I,almratory,
1
L-,
The oil which rernaiiicd frcini tlic origiilal cryst:tlliz:itioii had not solidified in a refrigerator after thrce n l o n t l i i , but one week after adding hydrogen chloride gas inore solid ester was recovered: 17.4 g. after one recrysta1liz;tti~iii. l-Menthyl I-p-toluenesulfinate was prepared as reported previously,2 except that after separation of the initiallyformed solid ester, a few crystals of t e t r a e t l i y l ~ r m i n o ~ ~ i u i ~ i chloride and some hydrogen cliloride gas were a d d e d . .i second crop was removed after one daj-, zmd retre:atmetit with quaternary chloride and liydrogcri chloride gave yet another crop. Tlie total yield of Lester was 8 0 . 7 ' ; . I-Menthyl I-p-Methoxybenzenesu1finate.-p-Metlirisybenzenesulfinic acid21 (27 g . , f1.157mole) \vas :ttldcd gr.aclually to 21.5 g. (0.18 tnolc) r i f tiiionyl chloride, the excess thionyl chloride \viis removed iii i'aczo, and tlie rc.;itluc cooled :ind diluted ivith 5!)inl. of dry ether. LI'itIi c!i!iliiig, 20 g. (0.128 mole) of I-menthol in 11 g . (0.1 f iiiiilc) of pFi-idine aiid 10 inl. of dry ether WRS added. More ether w t i added and the solution wished with dilute liydrocliloric acid. The ester, which w:is not very soluble in ether, \vas reciivered hy filtration, li~-drogenchloride ~ v x sp solution and it as refrigerated for three nrliich had crystallized alter this time, w:is sepxratcil m d tlic. ether \viis evaporated frrim the filtrate t o give xlditioii:ti product: yield 27.7 g. (0.089 m o l t , Gl'; crystallizations from aqueous acetorie, the 116-117.5' anti :t con,tant r(itatioi1 I J f [ a ] 1.2, acetone), : a ] 2 j ~ 193.5" (c 1.0, n i t r O b ~ l i ~ c l 1 ~ ~ . A n a l . Calcd. for C,;H,fiO S: C, 65.77; X , S . M ; S , 10.33. Found: C, 65.83; H , 8.32; S,10.11. TetraethylaninitJriiurii chloride stock sulutioiis in iiitrobenzene were prepared as previously.2 Care w a i ticccis'try to assure t h a t in the preparation of t h e chloride from the hydroxide no excess of hydrochloric acid was used, as it ~ : i s impossible to remnve hydrogen chloride fro111 the s:dt b y recrystallization. Hydrogen chloride stock solutiolis, in tiitrribenzene, were prepared by passing dry hydrogen chloride into dry iiitrobenzene. Exact concentrations werc determined iinincdiately preceding use, since hydrogen chloride is lost quitc rapidly even from dilute solutiotis in nitrobenzene. The kinetic determinations \yere made :it 25.00 d= 0.05', ;is reported previously. The spent siilutions froin a, scriei of kinetic r u m with i-iiienthyl l-p-toluencsulfin:tte, 111 o n e instance, were comhiiied and the nitrobenzene w:is reinovcd a t 1 0 - 3 mn., a t ,50'. 1niti:Llly 1.0 g. of ester, 0.008 g. o f tetr~ietliylanirii(iiiiurn chloride a n d 0.018 g. of IiycIriiFeii chloride were present. .I residue, 0.8 g., largely crystaliinc, remained, which after recrystallization weighed 0.67 g. :tilt1 had it 11i.p. 1()2-1()~'. .I mixed 1n.p. with pure I-riienth!.l I-p-tiiluenesulfiiiate was undepressed. After distillation of the nitrobenzene, a few rng. of white crystals deposited in tlie side-ami of the distilling flask. T h e odor, m . p . €IO', ;and niixcd 1ii.p. slloivetl these to hc />tcilucnesulfonyl chloride. I-Menthol, dissolved in nitrrJbcllzelle with atlrletl II! (lroget1 chloride and t e t r a e t l i y l a ~ ~ i n ~ o t i cliliiride, urr~ ~ ~ 1111i i changed in rotatioii after 16 hours a t 25'. TROT, S.Y . _~_..___
('rl,xti:i, Ill. ,?!I)
Vol. h l
I3raun m i i TV. K;ii>cr, D c r . , 66B,340 (1923).
(21) L. G a t t e r m a n n , i b i r i , 3 2 , l l l ( ( i (ISOij!
COiMMUNICA1'IONS '1'0T H E E D I T O R
sir:
CONVENIENT NEW PROCEDURES FOR T H E HYDROBORATION OF OLEFINS
Tlie hytlroburatiori reaction provides a ~wri\-ciiient new route from olefinic derivatives to organoboranes,' and to the many derivatives to which orgaiioboranes can be fl) H C Brown and R. C . Subba K a o , THISJ U W R N A I . . 78, SWJ4 (19.iCi). J . O w C h e i i i . , 2 2 , l 1 : j j ( 1 9 . i i ) .
\\'e have tlcscribctl procctlurcs which utilizctl sudiuiii borohydride, diglyme (diethylene glycol dimethyl ether) as solvent, arid boron trifluoridc etherate to liberate diborane from the salt. i t r e have learned t h a t the unavailability of one or inore 12) H. C. Brown and G. Zweifel, THIS Jou~V.41.. 81, % l i , L > l J (1959); H. C. Brown and K. Murray, i b i d . , 81, 4108 (1939); J . 13. Honeycutt. J r , , and J . h l , Riddle, ibid.. 81, 2393 (1959); h I . F. Hawthorne and J . A . D u p o n t . ibid.,8 0 , 5830 (1958).
