787
INDUSTRIAL A N D ENGINEERING CHEMIXTRY
August, 1923
Determination of Sugar in Cossettes by the Pellet Method‘ Volume Allowance for Marc and for the Combined Marc and Lead Precipitate By S. J. Osborn SUGAR BUILDING,DENVER,COLO.
I
until free from sugar with Determinations of the amount and specific gravity of the marc, cold water (about 1 liter), sugar in cassettes by and of the combined marc and lead precipitate, were made on Colorado and Nebraska beets of the 1922-23 campaign. The and drying a t 10s’ c. I n the Pellet method of hot water digestion+ the uolume allowance for the marc in 26 grams of beets was found this operation Some SOlUto be 0.6 ml., and for the combined marc and lead precipitate tion of the lead Precipitate normal weight, 26 grams, is could n o t be e n t i r e l y made UP to a volume of200 0.9 ml. The beets of the camPaign in question contained less than ml. of liquid. The flask is the normal percentage of marc. avoided. In the specific gravity degraduated to allow for the terminations, water, ethyl marc, or insoluble matter, which occupies a portion of the volume. While the volume alcohol, and methanol proved unsuitable on account of their allowance for the marc is variously statedj2 the method solvent action on the marc and the lead precipitate. This generally employed considers the volume of the marc in 26 action was more pronounced on the dried material. Xylene grams of beets to be 0.6 ml., and the flask is accordingly grad- was found to be a suitable liquid for the pycnometer weighings, uated a t 200.6 ml. This is the volume allowance prescribed and was employed, except as otherwise noted. It has no solvent in most of the standard methods of analysis. Pellet,3 action and was preferred to benzene on account of its higher however, in 1906 recalculated the data, with the conclusion boiling point. A very important part of the technic lies in the removal of occluded air from the marc. This seemed to be that 0.8 was a more accurate figure. It has long been recognized that marc is capable of no satisfactorily accomplished by placing the pycnometer. under strict definition, since some of the.marc constituents are par- a good vacuum for 30 minutes. The average results are given in tabular form. In the tially soluble in water, and the amount of marc found depends on the amount of washing and other conditions of the method fourth series the specific gravity was determined by weighing employed. Fortunately, variations due to such causes or the wet marc in water and drying afterwards to establish variations actually existing in the beets have a relatively the weight taken. This avoids the difficulty of removing small influence on the accuracy of the sugar determination, occluded air, but is open probably to some error caused by so that it is possible to establish and use an average value for the solvent action of the water. It will be noted that the percentages of marc found in the volume allowance without serious error. It is not clear why the volume allowance has always been this work are unusually low. This was undoubtedly a based on marc alone and the volume of the lead precipitate characteristic of the beets of the campaign in question, has been generally neglected. As there seemed to be no which mere considerably below the average in sugar content. good reason why the volume allowance should not take ac- Wohryzekj has used Skarblom’s data to show that beets count of both the marc and the lead precipitate, determina- low in sugar are also low in marc, and vice versa. A general tions were made, on the one hand, of marc alone, and on the relation of this kind has also been established from the writer’s other, of the combined marc and lead precipitate. The work own experience. On western Nebraska beets of another camwas carried out on beets grown in northern Colorado and paign-vis., 1920-21-the average of 114 determinations gave 4.39 per cent marc by Claessen’s method. western Nebraska of the 1922-23 campaign. Clacissen’s method4 was used for the marc determination, The following comparative determinations of the specific with the employment of a piece of linen cloth as a filtering gravity of dried marc were made in water and in xylene. Sp. Gr. in medium. Briefly described, this consists of extracting 26 Series No. of Sp. Gr. in grams of ground beets four times with 400 ml. of boiling No. Tests Water Xylene 1 3 1.582 1.488 water, allowing a period of digestion of 2 minutes in each 2 5 1.597 1.534 case. The residue was washed with a little alcohol and dried CONCLUSIONS at 105’ to 110” C. The combined marc and lead mechi-
Ii THE determination of
of the American Chemical Society, New Haven, Conn., April 2 to 7, 192; * Browne, “Handbook of Sugar Analysis,” p. 246. a 2 . Ver. deut. Zucker-Ind., 66, 11, 912 (1906). 4 I b i d . , 66, 11, 359 (1916).
However; it is likely that these errors are no greater than the actual variations which will be found in different beets a t 6
“Chemie der Zuckerindustrie,”~.36.
... ... ... Series No. 1
No. of Tests 74 42
---
-
AVERAGES OF MARCINVESTIGATIONS MARC-------MARC PLUSLEADPRECIPITATESp. G$ Volumee Sp. G: Volumee Purity % 20°/4 MI. % 20°/4 M1. 83 47 3.33 1 470 0.589 6 97 2 074 0.874 81 39 3 60 1.519 0.616 7 34 2 079 0.917 85 4 3.83 1 433 0.694 7 06 2 073 0 886 84.3 3.55 1 588 0.582 7.82 2 513 0 814 84.3 3.55 1.593 0.580 7.82 0.854 2 383
DISTRICT Sugar Colorado 1 4 80 2 Colorado 13 89 3 Nebraska 16 14.8 4A b Nebraska 24 14.41 4Bb Nebraska 24 14.41 0 I n 26 grams of cossettes. b I n Series A the specific gravity was determined by weighing the wet, extracted material in a pycnometer, and drylng afterwards. specific gravity was redetermined on the dried residues.
Liquid Used in Sp. Gr. Detn. Xylene Xylene Xylene Water Water
In Series B the
?@
INDUSTRIAL A N D E,VGINEERISG C H E X I S T R Y
various times. The results are all in close enough agreement to warrant the followine conclusions: 1-On the basis of the 1922-23 results, the volume of marc in 26 grams of cossettes is very close to 0.6 ml., so that, if the COSsette flask is graduated to take account of marc alone, its capacity should be 200.6 ml., the volume now usually employed. If the flask is graduated to take account of the combined marc and lead precipitate, and there seems to be no good reason why this is not a better basis than the marc alone, the volume should be 200.9 ml. 2-The 1922-23 beets are abnormally low in marc as well as sugar. A range of 4.00 to 4.25 per cent would probably not underestimate the average marc content of Colorado and Nebraska beets, With a marc content of 4.00 to 4.25 Der cent. the volume allowance for the combined marc and lead precipitate v
Vol. 15, No. 8
would be about 1.0 ml., and the cossette flask should accordingly be graduated at 201.0 ml. 3-The employment of a volume of 201.0 ml. for the cossette flask in place of 200.6 ml. would lower the polarization of a 16 per cent beet to the extent of 0.03. The error under the present volume allowance is therefore almost negligible, but there is no reason why the cossette flask should not be regraduated to conform with the best available data. ACKNOWLEDGMENT The writer's thanks are hereby expressed to C. C. Crawford, Geo. Goldfain, G. E. Stevens, and J. H. Zisch for the data and ideas in the of the investigation.
Conversion of Methyl Chloride to Methanol-11' By Ralph H. McKee and Stephen P. Burke COLUMBIA UNIVERSITY, NEWY O R X , ii.
N ORDER to interpret
I
the results obtained in the experimental work described in Part I, it was found. necessary to investigate in some degree the simultaneous reactions occurring in the reaction chamber. Ca(0H)z = CaO
+ HzO
(1)
In Part I the authors have shown, both experimentally and theoretically, that it is impossible to effect the direct hydrolysis of methyl chloride to yield methanol by means of steam alone. An experimental investigation of the use of metallic hydroxides to &ct this conversion was described, and it was shown that calcium hydroxide is the most advantageous. B y passing methyl chloride mixed with steam over calcium hydroxide at elevated temperatures, 95 per cent of the methyl chloride is converted into methanol and methyl ether, the remainder undergoing decomposition. A theoretical study of the reacting system was made and by means of an approximate calculation' of the free energy relationships (Nernst's heat theorem) the equilibrium points of the reactions inuolued were determined. The experimental results have been found to be in very good agreement with the theoretical values. In this article the simultaneous or side reactions encountered are studied, and detailed analyses of the factors and conditions influencing the conversion of methyl chloride to methanol are made. A catalytic process for the conoersion to methanol of the methyl ether obtained as a by-product is presented. I n conclusion, a brief rationale of the process is given and estimated production costs of methanol by this process are shown.
In order to determine whether, under the conditions obtaining during the runs discussed in Part I, any decomposition of the calcium hydroxide took place, the calcium hydroxide and chloride residues were examined for the presence of calcium oxide in many cases where anhydrous methyl chloride was used in the experiment. Its presence was detected only in very small amounts a t 400" and 450' C. This was to be expected, however, for at 350" C. the partial pressure of water due to this decomposition does not exceed 14 mm.2 It may be pointed out here that under these conditions magnesium hydroxide would be very unstable, for the partial pressure of water from magnesium hydroxide becomes equal to one atniosphere a t a temperature slightly above 200" C. For this reason it is far less desirable than calcium hydroxide in effecting the conversion of methyl chloride. CaClz HzO = Ca(0H)Z 2HC1 (2) No quantitative data on the extent of this reaction could be found in the literature. Therefore, a number of experiments were performed a t 350' C., with partial pressures of water in excess of 600 mm. These experiments were cawied out using part of the apparatus shown in Fig. 1 of Part I. The reaction tube was charged with C. P. anhydrous calcium chbride (containing approximately 10 per cent moisture) of 12-mesh size. Air was passed slowly through the humidifier heated to 93' C. (vapor pressure of water = 590 mm.), and thence through the reaction chamber, and on through the
+
1 2
Y.
+
Received December 4, 1922. Part I, THISJOURNAL, 18, 682 (1923). Dragert, Inaugural Dissertation, University of Berlin, 1914.
absorption bulbs containing distilled water with R few drops of phenolphthalein. The hydrogen chloride produced by thereaction was collected in the absorption train, and a t equal time intervals it was titrated with standard 0.1 N sodium hydroxide, The results obtained show that under these conditions, even at vapor pressures exceeding 600 mm., over a period of time greatly in excess of that required for the conversion of methyl chloride, the hydrolysis of calcium chloride would not exceed 2.5 per cent by weight. Thus, it can be concluded that the hydrolysis of the calcium chloride
formed in the reaction Ca(0H)n 4- 2CH3C1 = CaClz 3- 2CHaOH (3) by the presence of steam is practically inappreciable, and hence, that the displacement of the equilibrium of this reaction is negligible. Any displacement of the equilibrium to the right due to the hydrolysis of calcium chloride would probably be neutralized by the immediate reaction of hydrochloric acid with methanol. STUDYOF REACTION: CaClz 2CH30H = Ca(OH)z 2CH3Cl-This reaction, which is the reverse of that used to effect the conversion of methyl chloride to methanol, was investigated to determine the extent to which it could be carried out. The experimental method used here was very similar to that employed in the investigation of the hydrolysis of calcium chloride. The reaction tube was filled with C. P. anhydrous calcium chloride, and air was sent slowly through the humidifier and on through the reaction tube. In this case, however, the humidifier contained absolute methanol. The partial pressure of'the methanol was maintained as near to one atmosphere as possible. The absorption train was replaced by a 4-liter gas collection bottle, and the gases produced were collected directly. Several experiments were run with the same result. The methanol used (50 grams) was
+
+
