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JOHN
FV. KNOWLTON, N. CYRIL SCHIELTZ AND DUNCAN MACMILLAN
butyl peroxides have also been prepared having t-butyl alcohol of crystallization. 3. The pyrolysis of t-butyl hydroperoxide has been studied a t 95-100' and a t 250'. At 95100' t-butyl alcohol and oxygen are the only products formed, while a t 250' the products formed are acetone, methyl alcohol, t-butyl alcohol, formaldehyde and water.
[CONTRIBUTION FROM THE NORTHERN
Vol. 68
4. The pyrolysis of di-t-butyl peroxide has been studied a t 200, 250 and 300'. Acetone and ethane are the only products formed. 5. A free radical mechanism has been proposed to explain the pyrolysis of both t-butyl hydroperoxide and di-t-butyl peroxide. CAMBRIDGE 39, MASSACHUSETTS RECEIVED NOVEMBER 8, 1945
REGIONAL RESEARCH LABORATORY, PEORIA,
ILLINOIS']
Physical Chemical Properties of the 2,3-Butanediols BY JOHN W. K N O W L T ON. N , ~CYRILSCHIELTZ AND DUNCAN MACMILLAX During the course of this Laboratory's work on the production of the 2,3-butanediolsI i t has been necessary t o investigate a number of physical properties of these compounds. These investigations were made concurrently with the experiments on production, and consequently some of the earlier measurements were made on materials which were mixtures of stereo isomers. The most abundant material as i t came from the pilot plant had a composition of about 97.5% levo- and 2.5y0 meso-2,3-butanediol. Another culture used for the fermentation produced a mixture composed of t h e meso isomer with small amounts of the dextro rotatory form. At an early stage of the work it was fouhd that pure meso-2,3-butanediol could be obtained by fractional crystallization from isopropyl ether. Since the naturally occurring mixtures contained only one optically active form in addition to the meso isomer, separation by fractional distillation was possible. All three isomers were eventually obtained in pure condition by this method. I n this paper, values for the meso and dextro isomers are for the pure compounds. Many of the values for the levo form are also for the pure substance, and, in any case, the levo-2,3butanediol was a t least 97.5% pure, the contaminant being the meso isomer. The data in Table I were obtained on pure stereo isomers. The conductivities of the 2,3-butanediols in 0.5 N boric acid solution have been reported recently by Lees, Fulmer and Underkofler.: At this Laboratory a similar set of experiments in which 2 A' boric acid was used gave results in substantial agreement with those of Lees, Fulmer and Underkofler. It was found that in the case of levo-2,3-butanediol the conductivity increased markedly with increase in concentration, but that the conductivity of the meso form decreased (1) One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S . Department of Agriculture. Not copyrighted. (2) Present address: Bureau of Mines, U. S. Department of Interior, Dartlesville, Oklahoma. (3) Lees, Fulmer and Underkofler, Zowa Slate Coli. J. ScI., 18, 359 1944).
MISCELLANEOUS
TABLE I PHYSICAL CONSTASTS OF 2,s-
BUTANEDIOLS dextro Density a t 25', g./ml. Index of refraction, n o Surface tension, 2 5 O , dynes/cm. Viscosity, Hoeppler, centipoises 4358 5481 5791 5896 6234 6908
0.0872
0.9869
0.9939
1.4306 (25')
1.4308 ( 2 5 " )
1.4324 (35')
30.67
Rotatory dispersion:
mcso
levo
A,
30.61 4 1 . 1 (25') 2 1 . 8 (35")
6 5 . 6 (35')
A.
+25,24"/dcrn.
+15.28
-25.23' -15.32 12.95 -13 19 -11.38 -10.03
-
-I-13.05 +13.19 +11.41 $10.03
slightly with increased concentration. sults are presented in Table 11.
These re-
TABLE I1 SPECIFIC CONDUCTANCES OF SOLUTIONS OF levo- AND meso2,3-BUTANEDIOLS I N 2 N BORICACIDAT 20.0 levo
meso
(Optical rotation = 12.9'/dcm., A589S)
-
Molar concn.
0,000 (211' HaBOa) .50G ,253 .127
.063
y X
100
7.13 10.79 8.96 8.10 7.60
(Optical rotation O.OOo/dcm., A5896) Molar concn. y X 1@
0.452 .226 .113
G.50 6.76 6.91
Several aspects of solutions of 2,3-butanediols in water have been investigated. The freezing point diagrams of solutions of levo- and of meso2,3-butanediols are shown in Fig. 1. The optical rotation (X5896) for the meso form was 0.00' per decimeter; that of the levo form was - 13.0'. It will be noticed that a compound is formed consisting by weight of about 45% meso-2,3-butanediol and 55y0 water. The levo isomer does not form a compound with water. Refractive indices of solutions of levo-butanediol (97.8y0 pure) in water have been determined and are shown in Table 111.
Feb., 1946
209
PHYSICAL CHEMICAL PROPERTIES OF 2,3-BUTANEDIOLS
TABLE I11 REFRACTIVE INDICES OF SOLUTIONS OF lm0-2,3BTJTANEDIOL AND WATER Weight % diol ?IzD Weight % diol lt%D 100 1 ,4309 32.9 1.3727 90.7 1 4257 21.9 1.3521 83.0 1.4206 11.6 1.3462 71.0 1.4121 8.9 1.3430 0.0 1.3324 58.3 1,4010 45.0 1.3865
The vapor pressures of meso- and levo-2,3butanediols were determined a t several temperatures, using a Swietoslawski ebulliometer,4 in which the boiling temperature of the material under investigation was directly compared with the boiling temperature of water in a closed system filled with nitrogen gas, and whose pressure could be set arbitrarily. The boiling temperatures and the corresponding 10 30 50 70 90 vapor pressures were calculated from the experiWeight 2,3-butanediol, %. mental data. These values were then correlated Fig. 1.-Freezing point diagram of aqueous solutions of by the functions
- (2748.1/T) - (2852.58/T)
For levo-2,3-butanr:diol, log,op = 8.95845 For meso-2,3-butanediol, loglop = 9.14412
For the levo isomer the maximum deviation from the calculated pressure was 0.62%, and the average deviation was 0.27%. For the meso isomer the maximum deviation was 0.68%, and the average deviation was 0.40%. The boiling temperatures of solutions of levo2,3-butanediol in water were determined in a simple Swietoslawski ebulliometer, and directly compared with the temperature of water boiling under the same pressure. The butanediol used in this investigation had a rotation of - 12.9’ per decimeter for the sodium D lines, and was 97.8% pure. These da.ta are presented in Table IV. TABLE IV BOILINGPOINT
