April, 1922
THE JOURNAL OF IhTDUSTRIAL AND ENGINEERING CHEMIXTRY
RECOVERY OF ESTERS-TO determine whether the esters could be recovered by distillation, the mixtures were again used. Ten-cc. portions of the solutions were diluted with 100 cc. of water and distilled until 100 cc. of distillate were collected. Saponification of the distillates gave low results in all case?. Ten-cc. portions were then diluted with 100 cc. of 50 per cent ethyl alcohol and distilled until 100 cc. were collected. Saponification of the distillates showed that, although all the results were a little low, they were substantially higher than when water was used for dilution. The ethyl acetate solution showed a lower recovery than any other. In all cases the residues in the distillation flasks were saponified and no esters were found. Since there was a fairly high recovery of the ester by distillation with 50 per cent, alcohol and none was left in the distilling flask, it seemed possible that the loss might be due to ercape of a portion of the more volatile esters in the condenser. The fact that the loss was greatest with ethyl acetate seemed to support this view. In order to settle this point a mercury valve was placed in the Kohlrausch flask, which was used as a receiving flask, and the flask itself placed in ice water and protected from the heat of the burner. Even in the case of ethyl acetate recovery was now practically complete. With amyl acetate and amyl butyrate and the various mixtures used recovery was complete. -4number of distillations with 35 per cent alcohol as the diluting mixture gave lower results than when the 50 per cent solution was used. Ten cc. of Mixture A, to which 100 cc. of 50 per cent alcohol were added, were distilled from an ordinary roundbottomed, side-necked distilling flask carrying a thermometer to ascertain the distillation temperature. Below 103O C., 108 cc. distilled owr. The first 75-cc. portion of the distillate and the last 33-cc. portion were saponified separately. The first 7,5 cc. of the distillate contained practically all of the esters. Later experiments showed that the first 80 cc. of the dijtillate contained all of the esters. SIZE OF SAMPLE-The present standard of the Internal Revenue Bureau requires in certain imitation extracts not less than 5 g. of esters per 100 cc., calculated as ethyl acetate. This obviously requires the addition of more than 5 g. of esters per 100 cc. where esters of higher molecular weight than ethyl acetate are used. Determinations were made on 5 cc. of the Mixture C, containing higher molecular weight esters. There was practically no difference in the results obtained whether 5 or 10 cc. of the same were taken. A number of imitation extracts found on the market were saponified before and after distillation with 50 per cent alcohol. I n a number of samples it was found that considerably higher results were obtained when they mere saponified without distillation. Others showed no difference. It was concluded that in the former case some substance was present with the ester that reacted with the alkali. Upon evaporation to dryness over the steam bath it was found that these samples contained a reducing sugar. When a 5 per cent solution of glucose was digested with an excess of standard alkali solution on the steam bath for 1 hr., a substantial amount of alkali was consumed. It was apparent, therefore, that distillation after dilution with 50 per cent alcohol solution was necessary in order to obtain correct results. DENATURED ~~co~or,-Speciallydenatured alcohol, Formula 30 (100 parts of pure ethyl alcohol and 10 parts of refined methanol), was used in place of pure ethyl alcohol. The results were the same as when pure ethyl alcohol was used. This point is noted merely for the information of laboratories who use this formula of tax-free alcohol. It, was further found that many of the so-called pure es-
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ters upon the market contain only 90 per cent of the ester itself. The following method is now being used by the Bureau of Internal Revenue. METHOD Introduce 100 cc. of 50 per cent (by volume) ethyl alcohol (or specially denatured, Formula 30) into a 500-cc. Erlenmeyer flask and add 10 cc. of the extract (5 cc., in extracts containing as much as 5 per cent calculated as ethyl acetate). Connect the flask by means of a “gooseneck” with a vertical condenser, the end of which is fitted with a rubber stopper carrying a mercury valve. Attach a 100-cc. Kohlrausch flask to this rubber stopper, and distil the solution slowly until 100 cc. of distillate are collected. (It is very essential that the distillation apparatus be set up according to the above directions, as this reduces the loss from evaporation to a minimum.) Transfer the distillate to a 500-cc. Erlenmeyer flask, rinsing the Kohlrausch flask with a few cc. of 50 per cent alcohol. Add about 5 drops of phenolphthalein solution and neutralize to a first pink color, then add 0 . 1 N NaOH in about 25 per cent excess of the amount necessary for complete saponification. Stopper the flask tightly and allow to stand over night a t room temperature. Reflux for 0 . 5 hr. on a steam bath with an ordinary air condenser not less than 3 ft. in length. A piece of glass tubing, not too small, of the required length inserted in a rubber stopper makes an excellent condenser for this purpose. When the saponification is completed, cool rapidly to prelvent the absorption of carbon dioxide from the air, and titrate the excess of sodium hydroxide with 0 . 1 N acid. A blank determination should be carried out simultaneously, using the same quantities of alcohol and alkali. After correcting for the blank, calculate results as ethyl acetate. Each cc. of 0 . 1 N alkali is equivalent to 0.0088 g. of ethyl acetate.
ACKNOWLEDGMENT The author wishes to thank Arthur 1,. 3lorawski for assistance rendered in the work reported in this paper.
Our English Friends The season a t which Americans are accustomed to undertake European travel will soon be upon us and it seems proper t o call attention to the unusually cordial relations which exist between the Chemical Industry Club, Whitehall Place, London, and the Chemists’ Club of New York City. Both institutions desire to cultivate and provide for the social side of chemical industry and science by opening their doors to visiting members of either Club. This has not only promoted acquaintance and friendship on the part of chemists of both nations but is the means of favorable entree in the two countries for those interested in industrial plants and laboratories. The letters which have been exchanged between Mr. H. Edwin Coley, for the Chemical Industry Club, and Dr. T. R . Duggan, Trustee of the Chemists’ Club, convey warm and cordial greetings and assure a continuation of the kind feelings which have existed between the two Clubs and which should continue for many years.
A Memorial to Dr. Baskerville The students of the day and evening sessions of the College of the City of New York, together with the staff o€ the chemistry department, have started a fund t o establish a prize or scholarship in memory of Dr. Baskerville, head of the department of chemistry since 1904. It is hoped ultimately to establish a Baskerville Research Scholarship in Chemistry, t o be awarded annually to a student of t h e College. For the present it is planned t o present an annual prize. Dr. Prager, College of the City of New York, St. Nicholas Terrace and 139th St., is in charge of the fund.
A. Ph. A. Research G r a n t The American Pharmaceutical Association has available a sum amounting to $360.00 which will be expended after October 1, 1922, for the encouragement of research. Investigators desiring financial aid in their work should communicate before June 1, with Prof. H. V. Amy, Chairman, A. Ph. A. Research Committee, 115 West 68th St., New York City, giving their past record and outlining the particular line of work for which the grant is desired.
