5.
N. Balasubmhmanyam' Indian Institute of Science Bangalore, India
I
I
A Universal Azeotnpic Water separator
Apropos of the description of a universal steam distillation a p p a r a t u ~we , ~ wish to communicate a description of a universal azeotropic water separator (see figure) which has been developed in these lahoratories and has been in routine use for over a year now. The Dean-Stark apparatus for lighter-than-water entrainers has been in common use since its description in 1920.% Cork-and-glass assemblies employing heavier-than-water entrainers have been described in the "Organic Syntheses" volumes.' The present apparatus is a modification of a compact all-glass version described by Sukh Dev.5 When employing a lighter-than-water entrainer the stopcocks S, and Sz are closed. As the reaction proceeds, the transported water is run out from time to t,ime by setting S, to communicate with the outlet. When operating a heavier-than-water entrainer S1 is set to allow the solvent to flow into the feedback tube to be returned to the reaction vessel. Water overflows through S2when a layer of about 2 cm (20 ml) has been built up. The apparatus has proved itself eminently satisfactory when employed on preparations on scales met with in the "Organic Syntheses" and on many reactions requiling water removal in academic research (dehydration of maberials, ketalization, esterification, Cope-Knoevenagel condensations, etc). I t has, however, uot yet been strictly evaluated. I t is realized
' Present address: Department of Chemistry, Duke University, Durham, North Carolina. * WALLENBERGER. F. T.. O'CONNOR. W. F.. AND MORICONI. E. J., J. CHEM.ED&, 36,i51(1959). WEAN,E. W., AND STARK,D. D., Ind. Eng. Chem., 12, 486 (1920\. \----,.
' E . g . , CLARKE,H. T.,A N D DAVIS,A. W., in "Orgrtnie Syntheses," Coll. Vol. I, 2nd ed., John Wiley &Sons Inc., New York, 1946, pp. 261, 421; ADAMSR.,AND MARVEL, C. S., Ibid.,p. 368. [ DEV, S., J . Indian Chem. Soc., 30, 668 (1953); also a modification with provision for drying the returning entrainer; Ibid., 30, 447 (1963).
that skill in glass blowing is necessary for making it. But since the design is diagrammatic it is thought that it would be valuable as a teaching aid. The only critical dimension is the height difference of 20 mm hetween outlet and feedback tubes; a thermometer well (B 14) or a B 14 stopper closes the head of the column which should he lagged; the funnel F usually has enough irregularity near where it rests to allow equalization of pressure; otherwise a hole of 3-mm diameter should be made in the conical part. The author wishes to thank Professors Dilip K. Banerjee, B. H. Iyer, and S. Dev of the department of organic chemistry, Indian Institute of Science, for their interest in its development and S. K. Satyanarayana, glass technician, for making prototypes.
Volume 37, Number
9, September 1960
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475
