INDUSTRIAL AND ENGINEERING CHEMISTRY
616
When holdup is appreciable, Equation 31 may be solved by a graphical procedure after correctly establishing fN(z) and fH(z)by graphical means or otherwise. When the Smoker equation is valid, it is possible to obtain definite functions of the form of Equations 25 and 26, so that the second term of Equation 31 may be expressed and integrated in terms of Smoker’s quantities.
Generality of Equation 31 Equation 31 is general and in particular is independent of whether functions fx and fN are expressed by means of a Raoult law relation with reference to reflux ratio, by the diffusion concepts of Chdton and Colburn (a), or by some other theoretical or empirical relation. The integrations involved can always be performed graphically if mathematical methods fail, although the latter are usually preferable even if various approximations must be used because more general conclusions may be reached. The validity and usefulness of Equation 31 depend only upon the validity and nature of the basic functions fH and fN, and both experimental and mathematical work is under way with the objective of expressing this equation in a comparatively simple general form not involving any untested assumptions or approximations. Such an equation and those derived from it would obviously be powerful tools in studying the design and operation of batch fractionation columns, as well as other apparatus for batch separation processes of all types.
Nomenclature fH
= generalized function relating still composition to holdup
of more volatile component
VOL. 32, NO. 5
j~ = generalized function relating product composition to s t i composition in terms of a,n,R, or any other characteristics of the mixture, column, or conditions used in a dis-
tillation
j ~jz, = notations introduced for convenience
jh,fi c e
=
derivatives off^ andfnr, respectively, with respect to z
= holdup in condenser = base of natural system of logarithms
R = reflux ratio (ratio of overflow to product) (Other symbols have the same meaning as in the second paper of the series.)
Literature Cited Bogart, M. J. P., Tram. Am. Inst. Chem. Engrs., 33, 139 (1937). and Colburn, A. P., IND.ENQ.CHEM.,27, 255, Chilton, T.H., 904 (1935). Cryder, D . S., private communication. 24,482 (1932). Fenske, M. R., IND.ENQ.CHEM., Fenske, M. R.,“Science of Petroleum”, pp. 1630-2, Oxford Univ. Press, 1938. Ibid., pp. 1659-60. Lewis, W. K.,J. IND.ENO.CHEM.,1,522 (1909). Lewis, W.K.,and Robinson, C. S., Ibid., 14, 481 (1922). Peters, W. A,, Ibid., 15,402 (1923). Rosanoff, M. A., Bacon, C. W., and Schulze, J. F. W., J. Am. C h a . Soc., 36,2000 (1914). Smoker, E. H., Tram. Am. Inst. C h m . Engrs., 34, 166 (1938). Smoker, E.H.,and Rose, Arthur, unpublished work. Walker, W. H., Lewis, W. K.. McAdams, W. H., and Gilliland, E. R., “Principles of Chemical Engineering”, p. 532, New York, McGraw-Hill Book Co., 1937; Badger, W. L.,and McCabe, W. L., “Elements of Chemical Engineering”, p. 336, McGraw-Hill Book Co., 1936. Young, S.. “Distillation Principles and Processed’, p. 117, London, Macrnillan Co., 1922. (15) Ibid., p. 120. PR~SENTED before the Division of Physiod and Inorganic Chemietry at the 97th Meeting of the American Chemical Society, Bsltimore, Md.
Partly Aromatic Constitution of Artificial Carbohvdrate Coals J
E. BERL AND W. KOERBER Carnegie Institute of Technology, Pittsburgh, Penna.
ISCHER and co-workers (8) as well as Bone (2) have defended the viewpoint that natural bituminous coal could not have been formed from cellulose and other carbohydrates, because when these materials are oxidized with air under pressure in the presence of alkali or are oxidized with permanganate and alkali, only aliphatic oxidation products are obtained. Katural bituminous coals give oxidation products of partly aromatic nature just as lignin and its derivatives do. Therefore it was concluded that the aromatic lignin, and not the aliphatic carbohydrates, is the parent material of bituminous coals. The error of such a conclusion comes from the fact that those authors investigated the oxidation products of cellulose and other carbohydrates and not the oxidation products of cellulose coals. The chief object of this study was to determine whether cellulose coals would also give aromatic products through oxidation. If this could be confirmed, the objections of Fischer and of Bone would be void. The preparation, oxidation, and isolation of those products are described here.
F
Experiments on Cellulose Coal PREP-~RATIOK. Two hundred grams of cotton linters were heated in a rotating bomb with one liter of 0.05 N sodium hydroxide solution a t 325” C. A black solid coal and small amounts of black tar which solidified at room temperature were separated by filtration from the dark-colored acid solution. The analysis of these reaction products gave: carbon 79.93 per cent, hydrogen 4.89, ash 4.5 (calculated on an ashand water-free basis). OXIDATION. A 118.3-gram portion of this wet cellulose coal, corresponding to 74 grams of dry material, was ground to 150 mesh and oxidized with about 400 grams of hydrogen peroxide (1333 grams of 30 per cent hydrogen peroxide), diluted to about 5 per cent hydrogen peroxide content a t room temperature. Every day for 12 days 33 grams of hydrogen peroxide (110 grams of 30 per cent hydrogen peroxide) were added. In order to stabilize the peroxide, 20 CC. of a 40 per cent sodium silicate solution were added. The solution was kept slightly alkaline by the addition of the
TABLEI.
.ACIDS OBTAINED FROM . ~ R T I F I C l A L COAL BY OXIDATION WITH
Identified ns Acetotoluide Dimethyl ester Dimethyl ester Hexamethyl ester Dimethyl ester lsophthalir acid
Acid icetic Oxalic Diphenir Slellitic Terephthalic Ihophthalir
c.
H
Composition
% ' found-
78.22 40.80
70.82 78
!l. 82 .>7.9s
7.51 t.9i .,.E 4.19 r, .0' :1. 90
necessary amounts of sodium hydroxide .Ute] 12 clai tlw iiriattacked material (58 per cent) wab separated by centrifuging. The aolution was used for the deterniination of the carbon balance and the identification of snme of the acidFormed. CARBOX BALAXCE.The total amount of carbon n a y determined through oxidation of an aliquot with chroniic anti phosphoric acid according to the oxidation method (1). Carbonic acid mas determined by the same procedure nith phosphoric arid alone. The rarbon content of volatile acid. expressed ab acetic was calculated. The difference bet~veeii the total carbon content, determined by oxidation witlr c.hromic and phosphoric acid, and the sum of the carhnn expressed as carbonate, acetate, ancl oxalate cwrhoii reprewit. the aromatic hydrocarbons. NATUI~Eof OXIDATIOK PRODUCT^. The yrllon v ateri wliition obtained by the oxidation w t h alkalinr hydrogen peroxide was evaporated in uucuo. The resulting acidified with dilute sulfuiir acid, and after steam d volatile acids 5imilar t o acetic were separated. Acetic acid was identified as acetotoluide, melting point 110" C. Thib preparation did not shon any depression of melting point when mixed with a c. P. sample. The remaining brown solution contained other Ioiineri acids and colloidal silicic acid whirh was filteiecl off. Hea~clrit~ and filtrate were separately extracted with ether The evaporated extracts were dried over PzOs at j 0 " C They wert' wluble in ethei and partlv soluble in n ate] ~~
~
~~
'r.%BLE 11.
~~~
CARBOX DISTHIBTJTIOX I S SODlK.lI s.4LTS O F O X I D , \ TlON P R o D r C T s O F CELLCLOSE C O A L
Cnrbon
Granib
Total .As carbonic acid .is acetic acid . i s oxalic acid Difference, containing nrntnatic ncids
25.0 12.1 0.2 2., 9.i
Per
(:eiii
l(JO.0
48.5 2 .0 11.0 a8.5
The water-insoluble, slightly gray-green amorphous acid was separated by filtration and dissolved i n hot Tvater. So crystals could he obtained in this way. The amorpliour colorless substance with a melting interval between 240 " and 270" C. was methylated with diazomethane; slightly yellon material was formed. Treatment with methanol-water gave colorless needles with a melting point of 73" C. Analysis: carbon 70.82 per cent, hydrogen 5.22; calculated for ClsHlrOI: carbon 71.09 per cent, hydrogen 5.18. A sample mixed with the dimethyl ester of diphenic acid prepared from phenanthrene showed no depression in melting point. The water-soluble acids n w e treated with aIiimunia at 0' C. A crystalline colorless precipitate resulted. After acidification and ether extraction, the resulting free acid5 were methylated and their esters were sepal ated by distillation. The dimethyl ester of oxalic acid could be isolated (colorless needles, melting point 54" C.). Analysis: carbon 40.8 per cent, hydrogen 7.51; calculated for C4&01: carboil -10.66 per cent, hydrogen 5.12 Furtliernioie, the hexamethyl ester of mellitic acid (boiling point 220" C . a t 0.1 I I I I I I ot
-70 ralcrl--c H i2.4i
i 0 . titi
