Vol. 67
NOTES
1822
which is 3.8 X los times higher than that found with 0.05 M hydrogen chloride.* This confirms that the effect of ether on hydrogen chloride is not specific for the diazo ester decomposition. The factor for the menthone inversion (3.8 X loa) is smaller than for the diazo ester decomposition I 1.3 X lo4),presumably because the acid is more CHEMICAL LABORATORY dilute in the diazo ester decomposition and the NEWYORKCITY RECEIVED M A Y Z$.1043 effect ot the ether increases with greater dilution. DEPARTMENT OF H E A I T I I The rate of the menthone inversion with hydrogen bromide in ether is, in the range of the exThe Protolytic Activity of Hydrogen Chloride periments, proportional to the concentration of and of Hydrogen Bromide in Ethyl Ether the acid, while the inversion rate with hydrogen chloride is proportional to the square of the acid BY A. WEISSBERGER concentration.M The latter dependence agrees Hantzsch and Weissbergerlavbfound a remark- with the mechanism of the menthone inversion able difference in the reaction rate of diazoacetic with trichloroacetic acid in benzene,4nviz., a transiester with hydrogen chloride and hydrogen bro- tion from I-menthone to d-iso-menthone and mide in ethyl ether as a solvent. While 0.01 M vice versa by interaction of a binary acid menhvdr gen bromide and diazoacetic ester in ether thone complex with a further molecule of the acid. In the reaction with diazoacetic ester, 0.1 M AWA di a rate similar to that in tetrachloroethane, (2.22), a 0.01 M solution of hydrogen chloride and hydrogen bromide has about the same rate in diazoacetic ester in ether reacts about lo4 times ether (2.29 and in tetrachloroethane (2.52), and slower (0.000162). The difference between the 0.01 molar hydrogen chloride in tetrachloroethane two hydrogen halides, which appears to diminish has roughly the same rate (1.62). The correa t higher concentrations, is regarded as character- sponding rates2 for the 0.02 M hydrogen halides istic for the ethereal solutions of the hydrogen are 3.6, G and 3, respectively. With 0.02 and halides and not as specific for their reaction with 0.01 lzlr hydrogen chloride in toluene, the rates diazoacetic ester because dimethylaminoazoben- are 0.28 and 0.022, respectively, i. e., the rezene in ether containing 0.02 mole per liter of activity of the hydrogen chloride in toluene is hydrogen chloride is less red than a solution con- lower than in tetrachloroethane and shows a taining 0.007 mole per liter of hydrogen bromide. la greater drop with the dilution than in the latter In order to test further the difference between solvent. A direct comparison between the rate ethereal solutions of hydrogen chloride and hy- of the menthone inversion with hydrogen bromide drogen bromide, I-menthone was used as a re- in ether and that with hydrogen chloride in benagent.3 The optical inversion of this compound zene is not possible because of the different dewas measured as described previously.* The data pendency of the rate on the acid concentration which was mentioned above. However, it is 1 are listed in the table, K K' = .- Iog'O 'do, noteworthy that the rate of the rnenthone invert P m - Pf where po, pm and p ; are the rotation angles-at the sion with 0.0025 M hydrogen bromide in ether is time of the first reading, a t equilibrium and a t a 0.36, while the rate of the inversion with 0.0048 M hydrogen chloride in benzene is 0.00067. An time t after the first reading, re~pectively.~" effect of the excess menthone on the hydrogen MENTHONE0.5 MOLEILITER IN ETHYLETHER, 20.0 chloride may be responsible for the difference between the two hydrogen halides. However, the +0.1" Concn. in relatively low rate of both the menthone inversion k 4-k' (k + k')/Concn. Acid mole/liter and the diazo ester decomposition seems to indi0.0019 m h - 1 0.038 liters mole-1 rnin.-' HC1 0.05 cate that there is also an interference of the aro.07 140 HBr ,0005 matic solvent with hydrogen chloride. ,001 .15 150 ,0025 .30 144 This brings t o mind that Kablukoff6 obtained a crystalline compound from solutions of hydrogen I n the interval measured, the rate is propor- chloride in benzene. The same author found a tional t o the concentration of hydrogen bromide. sinking of the molecular conductivity of hydrogen By means of a linear extrapolation, one calculates chloride in ether with increasing dilution. This for the inversion of 0.5 M menthone with 0.05 hl observation was confirmed by Mounajede and may hydrogen bromide in ether a rate ( k k') = 7.2, indicate a peculiarity of solutions of hydrogen (1) (a) Hantzsch and Weissberger, 2. 9hysik. Ch:m., 126, 251 chloride in ether which has to do with their low (1927): (b) Weissberger, Dissertation, Leiprig. 1924. protolytic activity. (2) Rate constant of 2nd order reaction at 0' in liters mole - 1 min. - 1 (natural logarithms). No special experiments were made in order to (3) A. DGrken, Dissertation, Leiprig, 1934. make sure that the difference in the activity of (a) Weiuberger, TEISJOURNAL, 66, 102 (1943); (b) 66, 242 to demonstrate the reaction as the ethylenediamine destroys the reagent). The blue solution fades in about fifteen minutes, but may be stabilized by extraction with butyl alcohol. Another glyoxaline (4,5-diphenylglyoxalinc) has also been observed to give a blue color with Gibbs' reagent.
+
+
(4)
(1943); ( c ) 66,246(19431; (d) Weissberger and Tho-, (1943).
ibid., 65,402
(6) gablukoff. Z. phraik. Chrm., 4, 429 (1889). (6) Mounajed. Corn$. rrnd., 11 (1988).
in,
1628
NOTES
Sept., 1945
and pentabutyrylglucose by Hess and Messmer.l The general applicability of this latter procedure with the solvent, forniing ethanol and ethyl is shown by the results presented here. It has bromide. Such a reaction should be more rapid been found that the sugar esters can be obtained with hydrogen bromide, but it is not thought to be in quantitative yield by concentration of the reaca probable cause of the difference. The observa- tion mixture in vacuo after the esterification tions of Hantzsch and Weissberger'" and of process is complete. The excess pyridine, anhyDijrken2 call for a more thorough investigation dride and fatty acid formed, are removed,a leavand for comparative measurements of the 'con- ing the ester in a good state of purity. Further ductivity of the two hydrogen halides in ether. appropriate purification procedures can then be None of this work is planned by the author. The applied if desired, depending on the properties of above scant data and discussion may serve to and intended uses for the particular ester. This draw attention to a rather interesting problem of method of operation has the following advantages: (1) ease of operation with a minimum of manipuacid catalysis. lative steps, and (2) increased yields of esters in EASTMAN KODAKCOMPANY many cases. It is particularly useful as compared SYNTHETIC ORGANIC RESEARCH LABORATORY ROCHESTER $ N.Y. RECEIVED JUNE 21, 1945 to the conventional procedure when the desired ester is moderately water soluble (e.g., levoglucoAcetates, Propionates and Butyrates of Simple san triacetate). By use of the procedure described, the acetates, Saccharides propionates and butyrates of sucrose, diacetone BY IVAN A. WOLFF D-glucose a-methyl-D-glucoside, D-sorbitol, levoThe lower saturated fatty acid esters of carbo- glucosan and D-glucose have been prepared. hydrates are usually prepared by acylation with. Properties of the products are listed in Table I.
hydrogen bromide and hydrogen chloride in ether
is not caused by a reaction of hydrogen bromide
TARLE 1 PROPERI'IES OF THE SUGAR ESTERS'' Kutatioii uirisurernrnt~ Color State M. p., "C. [a]9'D in CHClr Concn. White Crystals 84-86 60.6 3
Substance Sucrose octaocetate crudeb Sucrose octapropionate crude White Sucrose octabutyrateCcrude Brown Diacetone D-glUCOSe monoacetate crude Off white Diacetone D-glucose monoacetate recryst. White Diacetone D-glucose monopropionateCcrude Yellow Diacetone D-glucose monopropionateCdistil. Water-white Diacetone n-glucose monobutyrateCcrude Yellow Diacetone D-glucose monobutyrateddistil. Water-white a-Methyl-D-glucoside tetraacetate crude White a-Methyl-D-glucoside tetrapropionateCcrude Viscous a-Methyl-D-glucoside tetrabutyrateCcrude Brown fluid D-Sorbitol hexaacetate crude Slightly yellow D-SOrbitOl hexaacetate recryst. White D-Sorbitol hexapropionateCcrude Slightly yellow D-Sorbitol hexabutyrateO crude Brown Levoglucosan triacetate crude White Levoglucosan tripropionateCdistil. White Levoglucosan tributyrateCdistil. Colorless Pentaacetyl-D-glucose crude White Pentapropionyl-D-glucosecrude V. visc. lgt. yellow Pentabutyrgl-D-glucose crude Visc. lgt. brown
Crystals Sirup Crystals Crystals Sirup Sirup sirup Sirup Crystals Sirup Sirup Crystals Crystals Sirup Sirup Crystals Crystals Sirup Crystals Sirup
*
Sirup
44-46
....... 51-58 57-61.5
+ + 52.7 + 46.5
- 34.3 - 36.9
. . . .. . . - 32.2 120.5-123d - 35.1 . .. . . . . - 31.3 121d 98-102
....... ...... . 91-97 97-98.5
.......
....... 107-110 37-38 170d 93-100
....... .......
- 33.3
+130.4 +114.5 +lO2.6 12.3 10.6 +14.1 17.4 61.5 56.8 - 34.56 73.2 53.7 44.5
+ + +
-
+ + +
1 3 2 1 2
1 2 1 3 3 2 3 3 4 3 1
2 2 1 2
2
---%
Acyl-
--
Calrd.
Found,
50.7 57.7 63.0 14.2 14.1 18.0 18.0 21.5 21.5 47.5 54.5 59.9 59.4 58.4 66.0 70.8 44.8 51.8 57.2 5.5.1 62.0 67.0
JIJ. 8 57.7 63.0
15.6
14.6 19.7 18.4 23.5 21.9 47.3 54.8 60.1 58.8 59.2 (55.6 70.2 44.2 52.0 57.3 54.9 61.6
67.0
a Melting points and boiling points are uncorrected. The word "crude" is used in this table to in'dicate the whole of the ester fraction obtained as a residue upon distillation of the non-ester bodies. These compounds are believed to be previously unreported in the literature. Boiling point at
