RICHARDG. RADSsca
46
VOl. 68
[CONrRIBUTION FROM THEh 3 S E A R C H LABOUTORY OF THE PITTSBURGH -ATE DIVISION]
GLASS CO., COLmSSIA CHEJHICAL
The Hydrolysis Rates of the Three Butadiene Monochlorohydrins BY RICHARD G.KADESCH
The addition of one molecule of hypochlorous acid to butadiene might possibly yield any of the three chlorohydrins, I, I1 and 111. CHdH-CH-CHtCl
I
OH
CHdH-CH--CH*OH
I CICHt-CH=CH-CH*OH I11
I
c1
I1
hydroxide at ' 0 was about 65% complete after one minute. In the hydrolysis of I1 by water at 70' the plot of chloride ion against time was asymptotic with the line correspondingto 92% hydrolysis. f t was concluded that there was 8% of a relatively inert impurity, probably I,8 present. This was deducted in order to get the true initial concentration of I1 for the calculation of k. One of the runs is shown in Table 11. All of the results are summarized in Table 111. It was possible to isolate 3,4epoxy-l-butene
These isomers, offer some interesting variations in structure; X is an a-chlorohydrin, I11 an allylic chloride and I1 has both of these structural features. TABLE I The kinetics of the hydrolysis of a few a-chlorohydrins have been studied by previous workers. HYDROLYSIS OF ~-CHLORO-~-BUTBN-~-OL (I) IN AQUEOUS SODIUM HYDROXIDE AT 0 ' The reactions of ethylene chlorohydrin, propylene chlorohydrin' and glycerol a-chlorohydrin* Initial I = NaOH = 0.0948 mole/liter 2nd order k, with hydroxide ion have been reported to be &.-I moles-' second order. The hydrolysis of propylene chloroTime, min. C1- conat. If& hydrin by water is stated to be bimolecular.* 0 O.oo00 .. The hydrolysis of allyl type chlorides in basic me2.5 .om2 1.88 dia has been shown to involve simultaneous uni7 .0495 1.52 molecular (SN')and bimolecular (SN~) mecha15 .0659 1.57 nisms,'-' the relative amounts of which depend on 30 .0782 1.71 the structure and the reaction conditions. Mean 1.67 Of the chlorohydrins studied in the present work I and I11 were prepared directly from butaTABLE I1 diene and hypochlorous acid6v7while I1 was pre- HYDROLYSIS OF 2-CHLOR03-BUTEN-1-OL(11) IN WATER AT pared by the addition of hydrochloric add to 3,430' epoxy-l-b~tene.~ ,7 Initial 11 = 0.0940 mole/liter In the present work the hydrolysis rates were 1st order Time, hr. C1- concn. k X 108, min.-' determined in aqueous solution, generally with 0 O.oo00 ... the chlorohydrin and sodium hydroxide (when 8.00 .OB0 0.768 used) at 0.1 .M,the reaction being followed by .0634 .731 25.17 the determination of chloride ion. With I and .0904 .753 72.12 sodium hydroxide several dif€erent relative concentrations were used without any appreciable Mean .751 change in the second order k's. Results of one of TABLE I11 these experiments are shown in Table I, the exHYDROLYSIS OF BUTADIENE MONOCHLOROHYDRINS treme speed of the reaction preventing a better Temp., Hydrolysis constancy in the k's due to the relatively large Chlorc2nd ord. k 1st ord. k OC. by time required in withdrawing the samples for hydrin I 0 NaOH .... 1.7 analysis. In the case of hydrolysis of I by base I 25 NaOH .... 30 at 25' and of I1 at 0' the k's are even greater and I 70 Water 5 . 5 X lo-' ... only rough values may be given. For example, 11 0 NaOH .... 70 the hydrolysis of 0.03 M I1 by 0.03 ill sodium (1) (a) Smith, Holm and Svenonius. 2. )hyrik. Chem., 161, 153 (1931); (b) Smith, el 01.. Ber., I I B , 3143 (1922). and earlier papen. (2) Drozdov and Cherntzov, J . Ger. Chem. (U.S.S. R.),1, 1305 (1934); C. A , . I # , 3308 (1935); Smith, el ol., Bw.,61, 1709 (1928), and earlier papers. (3) Kednnskii and Merson, C. A . , $1, 6092 (1937)). (4) Hughes, Trans. Faraday Soc., 87, 603 (1941). (5) Young and Andrews. THISJOURNAL, 66,421 (1944). (6) (a) I'etrov, J . Ccn. Chem. (U.S. S. R.),(I, 131 (1938); C.A . , 51, 4524, 5369 (1938); (b) Petrov. J . Gen. Chem. (U.S.S. R . ) , 11, 991 (1941); C.A . , 87, 1699 (1943). (7) R. G . Kadesch. Tars JOURNAL, 6% 41 (1946).
I1 I1 I1 I1 I11 I11 I11
30
50
60 70 30 30 50
Water Water Water Water Water NaOH Water
7.61 X
lo-'
0.0094
.om
.068 .0012
.... .022
... ... ...
... ... 0.89
...
( 8 ) The impurity ia regarded as I because of the method of prepatation (addition of hydrochloric add to 3.4-epoxy-1-butene) and because the boiling points of I and I1 at 80 mm. lie only 3' apart.
in 87% yield after the treatment of 2.5% aqueous hydrolyze by the simultaneous operation of the SN'and SN'mechanisms.* Whether or not alkali I with sodium hydroxide at room temperature. would bring the SN' mechamsm ' into play for 11, Discussion thus increasing its hydrolysis rate (which it does The second order kinetics for the a-chloro- not do in the case of a dose andog, 3-chloro-lhydrin + epoxide conversion observed in the butene, that hydrolyzes solely by the S N mech~ present work and elsewhere's' is consistent with anism*J) cannot be determined since extremely the mechanism rapid epoxide formation intervenes. RI
/ICICH&H20- + H i 0 k i ClCHzCHzOO- +CHsCHz + C1-
ClCH2CHtOH $. OH-
Y
ki
(1)
Experimental
(2)
Prepmation of I-Chlor~buten-2-01 (I).-I was obtained by the addition of hypochlorous acid t o butadiene
which has been suggested by Winstein and
Lucas.gb The extreme speed of the reaction and the occurrence of inversionD are a consequence of the intramolecular nucleophilic (5"') displacement of step 2. Nucleophilic displacement reactions in general involve Walden inversion1oand the rapidity of this displacement arises from the close proximity in space of the reacting groups in the intermediate &oxide ion. The rate expression derived from this mechanism is
which indicates that the over-all rate depends both on the acidity of the chlorohydrin (kJk-1, the equilibriuni constant of step 1) and on b." The available data are listed below in the order of decreasing B. k
RiCH(0H)CHILCI Ri R.¶ H C 5 C ! H (11) H (I) C 5 C H C E H H H H H
min. -1 g.
Temp.,
70 1.7 6.5 0.624.0
0 0
moles-11.
0.64
oc.
ia 26 26
Ret. Prrrult work preantwork 1 1
Preaent work
Attempts to interpret these data on the basis of the usual ef€ects of substituents R1 and Rt on the acid strength of organic molecules and on the rates of SN)type reactions were only partially successful. It may be that substituents also exert a steric influence" on the formation of the threemembered epoxide ring in a manner similar to that postulated by Thorpe, Ingold, et al., for certain ring closures to give cyclopropane derivatiVeS.18
The pronounced increase in the rate of hydrolysis of I11 in the presence of alkaIi is similar to the behavior observed for allyl and crotyl ~hlorides.~.~ The latter has been shown to (Q) (a) Wilson and Luau,Tam JOWBNAI., 66,2396 (1988); (b) Winrteip and Lucas, ibid.. 81, 1576 (lQa0); (e) LUCM.Schlotter and Jones,ibid., U, 2!2 (1W1);(d) Winstein and Hendemon, ibid., 66,1196 (1813); (e) Revlos pod Tidier, C. A., m,028 (1946). (10) Hpmmett, "Physical Organic Chemistry," McGrnw-Eill Book Company, New Y a k , N. Y., lW, Chap. VI. (11) Thi. rulilta from the rmaonrble expectation that ka &-I. (12) This was muggestul by Dr. S. G. cohen. (13) Wataon, "Modern Theories of Organic Chemistry," 2nd ed.. Oxford University Pres. New York. N. Y.,19411, p. 280.
