December 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
T h e 30 square foot filter has five auxiliary centrifugal pumps, one vacuum pump, one compressor for refrigeration, one blower, one agitator, and a motor drive; hence no decrease in the specified 15 h.p. is indicated. Pover may be calculated at a lower figure and costs from 0.5 to 3.0 cents per kw.-hr. are reported, depending upon the specific locality and the magnitude of the load (1). The validity of this point is acknowledged. Maintenance is based on pilot plant observations and one large producer of crude aluminum sulfate has advised t h a t 10% of capital cost is indicated, representing an increase of 1% over the published figure. I n any totally enclosed unit with volatiles, packings must be frkquently replaced, leaks quickly repaired, and moving surfaces adequately protected by stuffing boxes. K i t h respect to the comment regarding cooling water requirements, the values chosen were believed to be a correct balance betm-een the two factors of heat exchange surface and cooling Kater volume. I n conclusion, the authors wish t o thank the critic for stimulating interest in the process, and if this Bureau of Mines development has industrial application, they should be pleased to assist in its exploitation. I t is the authors’ opinion t h a t conservatism in the preparation of cost estimates based upon pilot plant investigations is a desirable policy.
1683
Synthesis of DDT with Chlorosulfonic Acid as the Condensation Agent
SIR:Our attention has been called t o three recent references O D the preparation of technical D D T by the sulfuric acitl-oleum method, one by Mosher, Cannon, Conroy, Van Strien, and Spalding (4),another by Seil, h i e s , and 1IcIIhinney ( 5 ) , and the last a British patent source (1j . The l a t t w describes srvcral experiments wherein the conditions approximate those employed by Seil and co-vorkers (51, with but one significant difference: An initial 2 5 5 oleum concentration is employed in contrast t o the 1 0 . 2 5 initial oleum concentration taken by Sei1 and associatw. The purity of the technical product in the British report vaiiw from 75 to 97% actual DDT and no data are given for the yields of technical product obtained. The article by J1osht.r arid associates (4)embraces a complete account of the W.P.B. IIDT Report Series, 44-1 through 44-12. From their reported yields of technical products and respective setting points, together with the corresponding percentage purity values established from Fleck and Preston’s (3) setting point composition curve, calculated equivalent percentage theoretical yields of pure D D T varying from 34.7 t o 7 5 . 2 7 are established. The conclusions of these authors (4)in reference t o the experimental conditions lcading t o a niaxinium xield of 97% technical product of 77% pnre DDT content have been called attention t o in our paper (I). LITERATURE CITED The pilot plant data and observations by Iieil and associates 11) Perry, J. H., “Chemical Engineer’s Handbook,” p. 2490, New ( 5 ) of the Canadian Chemical Karfare Laboratories arc cven York, hIcGraw-Hill Book Co., 1941. more significant for comparison purposes. Thus, these authors claim average yields of 70% technical DDT (which analyzed E. A. GEE W.K. CUNNINGHAM 71.2% pure DDT) and actual yields of 8594 technical D D T in the latter stages of their production operations. Thcse data R. A. H E ~ K D L U . S. BUREAU OF MINES correspond t o calculated equivalent percentage theoretical yields W A S H I N Q T O N , D . C. of 50 to 60% pure DDT. .\loreover, the pilot plant Keil and co-workers ( 6 ) show clearly, when the opcra ratio of acid to organic reagents was increased from 2 : 1 t o 5 : 1 or as expressed otherwise, when the mole ratio of sulfuric acicl to chloral n-as increased from 8: 1 to 20: 1, a yield of 90% technical product or a calculated equivalent 64% theoretical yicld of pure D D T !vas obtained. However, Sei1 and associates admit that SIR: I n a paper entitled “Radial Chromatography in Inoperations under such conditions “are not economically sound, as dustry” [IND.ENG.CFIEM.,39,938-40 (1947)] Hopf describes a n the slight gain [in yield] did not justify the cost of the esces.~acid apparatus invented by him and called “chromatofuge.” This used.” Therefore, from a consideration of all published references ’ apparatus combines the use of the principles of chromatographic t o the sulfuric acid-leum process wherein complete data are adsorption and centrifugal power. available, it would appear t h a t an economic operating limit, In July 1943, I published a n article on chromatographic a d s o r p corresponding to a 50 t o 6 2 s (and an optimuni average, approsition in which I described an apparatus invented by myself and mating 60 to 62%) theoretical yield of pure DDT, is about all constructed on the same principles. It was distributed by the Baroid Sales Division, Iiational Lead Company, Los Angeles, that may reasonably be expected of this process. By contrast, Calif. our one-step chlorosulfonic acid method wherein essentially OTTO ICOSIG metathetical quantities of reactants were employed, gave under 701 S o GRAVERCY DRIVE variable operating conditions 50 t o 69% and undcsr optimum COS AiYGELEB 5 , C A L I F . experimental conditions 67 t o 69% theoretical yields of pure
Radial Chromatography in Industry
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DDT.
SIR: Konig’s 1913 publication, based on a previous publication ‘by Brown, unfortunately was not available t o scientists in Europe and, I believe, some parts of the United States. The apparatus described by him certainly uses the same principles described by me, although it seems t o have been intended solely as an analytical aid. The idea of using centrifugal torcw as a n aid t o the passage of liquid in chromatography has been worked on t o my knowledge in several laboratories all over the Tvorld. I believe, however, I a m correct in saying that my work contains the first successful adaptation of the principle to an industrial problem t h a t has been published in a n internationally read journal.
LITERATURE CITED
(1) Balaban, I. E., and Calvert, R. D. (to Geigy Co., Ltd.), Brit. Patent 581,156 (Oct. 17, 1945). (2) Cook, W. A., Cook, K. H., and Rueggeberg, W. H . C., IIFD. END.CHEY.,39, 868-70 (1947). (3)Fleck, E.E., and Preston, R. K., Soap Sunit. Chemicals, 21, (5). 11-13 (1945). (4) hIosher. H. S., Cannon, M R., Conroy, E. .4.,Van Strien, R E., and Spalding. D. P., IND.ENG.CHEM.,38,916-23 (1946). ( 5 ) Neil, J.. Ames, A. K., and McIlhinney, A. E., Can. Chem. Procese Ind., 30 ( 8 ) , 77-80 (1946)
WALTERA. COOK K. H. COOK W. H. C. RUEGGEBERG
PETERP. HOPF 12 SEYVOUR H O U B E , .&LEION A v E . , S.W. 8 LONDON,EXGLAKD
UNIVERSITY OF .%=RON AKRON,OHIO
