L. OERTLING. MARTINDALE'S LE RADIUM. Apparatus and Reagents PUBLIE TOUT CE QUI CONCERNE LES SILICATES OF SODA AND POTASH. OLDEST and MOST RELIABLE MAKE, For Chemical and Bacteriological Research. MARTINDALE'S BURETTE STAND IN ANY FORM PURCHASED FOR CASH. 40 and 42, CLERKENWELL ROAD L.C. Photographic Residues Reduced and Purchased. SULPHUROUS ACID and SULPHITES. Liquid SO, in Syphons, for Lectures, &c. PHOSPHORIC ACID and PHOSPHATES. CARAMELS & COLORINGS for all purposes. WILLIAM GOSSAGE SONS, Ltd., Soap Works, Widnes A. BOAKE, ROBERTS, & CO. (LIMITED), LONDON AGENTO-CLIFFORD CHRISTOPHERSON & CO., 31, Mincing Lane, London, E.C., who hold stock ready for delivery Stratford, London, E, EDITED BY SIR WILLIAM CROOKES, O.M., D.Sc., F.R.S., &c. No. 2693.-JULY 7, 1911. ON THE PREPARATION OF ACETAMIDE.* By M. A. ROSANOFF, LOUISE GULICK, and H. K. LARKIN. 1. Methods Used Hitherto. ACETAMIDE has long been prepared by the action of aqueous ammonia upon ethyl acetate, as originally proposed by Dumas, Malaguti, and Leblanc (Comptes Rendus, 1847, xxv., 657). The reaction mixture has no effect upon iron, and so the process can be carried out on a considerable scale in iron autoclaves. The preparation of amides from the ammonium salts of the corresponding acids was first introduced by Dumas (Ann. Chim. Phys., 1830, [2], xliv., 142). The details of this method, as now generally employed for the preparation of acetamide on a laboratory scale, were worked out by Hofmann (Berichte, 1882, xv., 977). Hofmann sums up the condition of the preparative method at the time he undertook its amelioration in the following words : "If, however, the preparation of amides by treating esters with ammonia leaves much to be desired, the yields obtained by the distillation of ammonium salts are even less satisfactory. Experiments on the preparation of acetamide by this method have been published by Kündig (Ann. Chem. Pharm., 1858, cv., 277), who obtained, in the most favourable case, using glacial acetic acid saturated with ammonia gas, something over 25 per cent of the theoretical yield. In all these distillations streams of ammonia escape at first, which naturally reduces the yield of amide. Petersen (Ann. Chem. Pharm., 1858, cvii., 331), who, at Bunsen's suggestion, modified the experiment by distilling a mixture of equivalent quantities of fused sodium acetate and sal ammoniac, states that acetamide may thus be easily and advantageously prepared, but says nothing concerning the percentage yield. When this experiment was repeated perfectly pure acetamide was obtained directly, but in this case too a large quantity of ammonia was lost, and the final yield of acetamide amounted to only 20 per cent of theory.' Hofmann's method, as given in its optimum form by Gattermann ("Practical Methods of Organic Chemistry," trans. by Schober, New York, 1907), consists in neutralising 75 grms. of acetic acid with ammonium carbonate and heating in sealed tubes for five hours at 225°. The reaction product is subjected to fractional distillation; the fraction passing over between 180° and 230° is collected separately, and on solidification pressed out on a drying-plate. The pressed out crystals are re-distilled, yielding about 40 grms. of almost pure acetamide. This operation, however, cannot be carried out on a Contribution from the Chemical Laboratories of Clark University, Worcester, Mass. large scale. We quote from Hofmann (loc. cit., p. 981): -"Unfortunately this operation cannot be carried out, like the treatment of esters with ammonia, in iron autoclaves, as these are strongly attacked. Acetamide will, therefore, be best prepared in the future, as heretofore, by treating the ester with ammonia at ordinary temperatures." have been proposed since 1882. Schultze (Journ. Prakt. Chem., 1883, xxvii., 512) warms ammonium acetate with acetic anhydride, using no less than 130 grms. of anhydride to 100 grms. of the acetate. This, however, is not only costly, but unquestionably yields much diacetamide together with acetamide. Keller (Fourn. Prakt. Chem., 1885, xxxi., 364) distils ammonium acetate in a current of ammonia. We have tried out this method, but with no satisfactory results; unless one carries out a great many re-distillations, which is disproportionately laborious, the yield is very small (generally about 12 per cent of theory). One or two modifications of the Hofmann method Obviously, almost as much acetamide could be obtained at 140° as at 220°. The reason that the higher temperature is generally employed is that at lower temperatures the reaction is impracticably slow. This suggested the possibility of rendering the old method simple and convenient by employing a suitable catalytic agent. The most appropriate catalyst, apparently, was suggested by the following simple considerations. From the fact that the hydrolysis of amides is catalysed by acids, the inference was drawn that acids would also hasten the opposite reaction, i.e., amide formation. Mineral acids could not be used as they would take up the ammonia from the ammonium acetate. Organic acids generally would yield their own amides in addition to acetamide. Acetic acid alone could do no harm, and might be confidently expected to promote the reaction catalytically. Theoretically it was also clear that, by increasing the volume of the reacting mixture, the acid catalyser would improve the yield, since the reaction involves the formation of two molecules (amide and water) from a single molecule (ammonium acetate). This might be expected to counterbalance the slight diminution of yield produced by the temperature lowering. Experiment soon showed that in the presence of an excess of acetic acid the amide formation really took place with considerable velocity in open vessels. It remained to determine the essential details of the preparation, and this required a large number of trials. The following directions will be found to yield satisfactory results. First, good dry ammonium acetate is prepared by neutralising glacial acetic acid with pulverised ammonium carbonate at about 50°, allowing to cool, draining off the crystals, and pressing them out twice or three times with filter-paper. The product so obtained contains very nearly 98 per cent of the pure salt. (NOTE.-The use of ammonium acetate freed from water is best for the obvious reason that water promotes hydrolysis of the amide, and hence necessarily diminishes the yield. Commercial ammonium acetate contains more or less free acid and is unreliable, unless neutralised and pressed out afresh). have shown that even two hours would have sufficed) at 225° in sealed tubes. The product was subjected to fractional distillation as described above. The yield was about 56 grms. There is certainly no advantage in using sealed tubes. Our product boils at 214-216°, which shows it to be nearly pure acetamide. Clark University, Worcester, Mass., A STUDY OF THE FRUIT OF THE By BENTON R. ANDERSON. REEDER (CHEMICAL NEWS, xcvi., 199) gives analysis of His results were mainly qualitative, so it occurred to us it might be profitable to make a more quantitative study of the fruit of this interesting species. the fruit of Solanum dulcamara. The Solanum dulcamara, or woody night-shade, a native of Europe, was introduced into the United States soon after the discovery of America. The flowers of this plant resemble the potato, but are smaller. The fruit is a red ovate berry, and, on account of its luscious appearance, is often eaten by accident. The berry is quite sweet owing to the large content of sugars. When burned, it gives off three distinct odours; first, an odour similar to that of boiling molasses; secondly, an odour resembling burnt sugar; lastly, an odour of The fruit is easily crushed in an agate burning wood. There were 304 grms. of berries available for the analysis, which were obtained in August, 1906, at Sylvan Beach, New York. The average weight of a berry was mortar. 100 grms. of this ammonium acetate (corresponding to 75 grms. of acetic acid) and 113 grms. glacial acetic acid (ratio: Imol. acetate to 15 mols. acid) are boiled in a one-litre flask, with reflux condenser, for five hours. The product is rapidly distilled over with minimum loss and subjected to fractionation (again out of a one-litre flask) with the aid of a two-bulb Wurtz stillhead. (This distillation materially improves the yield). This operation should be carried out as slowly as possible. Three fractions are collected separately: (1) the fraction passing over below 180°; (2) the fraction passing over between 180° and 2130; (3) the fraction passing over above 213°. During the dis-0125 grm. tilling of fraction 3 the stillhead is unnecessary. The second fraction (180-213°) is slowly re-distilled with the Wurtz stillhead, and the portion passing over above 213° is added to fraction 3, the remainder being added to fraction I. The original product is thus divided into a low-boiling and a high boiling fraction. The former may again be neutralised with ammonium carbonate, and the resulting salt used for a new preparation. The high-boiling fraction, on thorough solidification, is twice pressed out with filter-paper. The dry crystals (practically pure acetamide) weigh over 60 grms., or 20 grms. more than the product obtained by the use of sealed tubes according to the Hofmann-Gattermann directions. The yield is, however, slightly variable, depending on the quality of the ammonium acetate used and especially on the care with which the fractionation is carried out. (NOTE. In two consecutive preparations carefully carried out in this Laboratory by Mr. H. R. Godfrey, the yields were respectively 62 grms. and 63.5 grms. At the suggestion of Prof. William A. Noyes, Mr. Godfrey was also requested to try the preparation of acetamide from ammonia and an excess of acetic acid directly, without isolating the ammonium acetate). Dry ammonia gas was introduced into 188 grms. Kahlbaum's glacial acetic acid (=75 grms. +113 grms. excess, as above) until the increase in weight amounted to 213 grms. This was changed to acetamide according to our directions. Two such consecutive trials yielded respectively 633 grms. and 622 grms. acetamide. The simplification will be valuable when only one preparation is to be carried out). It is obvious that the above directions permit of transforming ammonium acetate into acetamide on as large a scale as may be desired, and ought to lead to a considerable reduction of the present price of acetamide, and in order to make certain that the low temperature employed did not after all materially diminish the yield, some experiments were carried out on the following plan:-100 grms. of our fairly dry ammonium acetate and 113 grms. of acetic acid were heated for three hours (experiments The Sugars. 200 grms. of the fruit were used in the sugar extraction. They were placed in a litre flask, fitted with an inverted condenser, and were treated with boiling alcohol for 250 hours. Each day the alcohol was removed and a fresh portion supplied. The alcoholic extract was distilled off, leaving a thick syrup in the flask. The process was continued for thirty days; at the end of this time the extract failed to reduce Fehling's solution. The colour of the alcoholic extract was a deep wine colour, but at the end of thirty days the extract was almost colourless, and distilled water was substituted for the alcohol. The berries had remained firm, but soon became mushy under the water treatment. The water extract did not show a clear wine colour, but was black and muddy. Fourteen days more were required to remove all colouration and the remainder of the sugars. The percentage of the sugars was determined by the reduction of Fehling's solution. The solution was standardised, and it was found that 10 cc. were completely reduced by o'05 grm. of sugar. 15 cc. of the litre solution of the alcoholic sugar extract was added to 50 cc. of boiling water, and titrated with the Fehling's solution. The end-point of the reaction was determined by filtering a small portion from time to time, and pouring the filtrate back until the sugars had no more reducing power. The filtrate was a straw colour until the end-point was reached, when it became a bright blue. The change in colour could be brought about either way by the addition of three drops of Fehling's solution or the same of the sugar solution, so the test appeared to be satisfactory. The water extract was determined in exactly the same manner. There were found to be 610 grms. of sugar in the alcoholic extract and 105 in the water extract. As 200 grms. of berries were used in the extractions, the above weights correspond to 31.55 per cent of sugar. The two portions were evaporated to dryness, and the odour resembled burnt sugar. The residue was black and gummy, having the sweetish taste of the original berry. CHEMICAL NEWS, July 7, 1911 Two Simple Forms of Gas-pressure Regulators. A part of the residue was treated with distilled water and bone-black. The solution after being filtered out had the red colour of the alcoholic extract. It was evaporated to dryness for treatment with the phenylhydrazine-hydrochloride. A mixture of 2 cc. of distilled water, o'or grm. sugar, o'04 grm. phenylhydrazine, and 003 grm. sodium acetate were put in a test tube, and the tube placed in a boiling water-bath. The time required for the osazone formation was taken. Several tests pointed to fructose. A loss of 46.05 per cent was found when the berries were dried and weighed after the extractions. The berries were reduced in size, and were much shrivelled. The Oils The dried berries from the sugar extraction weighed 106.7 grms. These were placed in a litre flask fitted with an inverted condenser, and were treated with ethyl ether. Three hundred and fifty hours were required to extract the oils. The ether was removed from the extract by distillation. The oils were then purified with bone-black and ether, using a flask and inverted condenser. The purified oil was a beautiful amber colour, and quite viscous. The specific gravity was found to be 0.9603. The saponification of the oil was made according to the Koetstorfer's method. The oil was very difficult to saponify, four days being necessary. Several saponifications were made in shorter time, but the numbers were much too high. The equivalent was found to be 306. 10103 grms. of oil required 33 cc. of NaOH. The figures indicate that it is one of the castor-oil group. After the removal of the unsaponifiable portion with ether, the acids were separated. They were principally ricinolic acid, according to the descriptions in the text-books. Each berry has four small seeds which contain the oil. The total weight of the oil extracted was 18 3138 grms. from the original 200 grms. of berries, equivalent to a total of 9.1569 per cent. The Proteins. A few of the fresh berries were crushed and boiled in distilled water. A small portion of this extract was heated and nitric acid added. A yellowish tinge showed a trace of albumen. The nitrogen was determined by the Kjeldahl method. Two grms. of berries were treated, and the analysis showed o'01868 grm. of nitrogen, equivalent to o'934 per cent. The Acids. The acid tests were made from the sugar extraction, after the purification with the bone-black. A portion of the extract was heated in a beaker glass, and ammonia and calcium chloride were added. The small precipitate which appeared was filtered cold to allow the citrate to pass through. The precipitate was soluble in acetic acid, and so constituted the test for tartaric acid. A portion of the extract was added to a solution of caustic soda, and lime-water was added. When heated a precipitate formed, indicating citric acid. Acetic acid was present, probably due to fermentation. The Alkaloids. A modified Dunstan and Ransom's method was used for this analysis. A few grms. of the alcoholic extract were warmed with dilute hydrochloric acid, then filtered and washed with hot hydrochloric acid. The filtrate was shaken in a stoppered cylinder together with a few centimetres of chloroform. The chloroform was then poured off, and evaporated on the water-bath. The pure alkaloid was left in the crucible. It weighed 0.003 grm. This was from 10 cc. of the litre solution of the extract from the original 200 grms. of berries. This amounted to o.15 per cent. According to Allen's "Organic Analysis" the alkaloid seemed to be an isomer of atropine, Solanin. The Ash. Four portions of about 2 grms. each were ashed in a 100 cc. platinum dish. From the first portion a dolomite analysis was made, silica, iron, alumina, calcium, and 3 magnesium being determined. From the second portion the alkalis were determined by a modification of the J. Lawrence Smith method. From the third portion the sulphates were determined by precipitation with barium chloride. The fourth portion was used for the phosphate determination, the magnesia mixture being used to precipitate the acid. The results were as follows. First Portion.-Weight of Berries, 2.1995 grms.; SiO 2 MgO Per cent. 10'14 6.87 7.78 7'43 I'73 The total is 90'73 per cent of the ash. The remainder is organic matter which could not be oxidised and a small amount of carbon dioxide. After the sugar and oil extractions had been made an analysis was made of the residue. The results in every case were almost the same as the above. A much larger bulk of the residue was needed to weigh out a grm. One grm. ashed weighed oot 16 grm., as compared with 0.0519 before the extraction of the sugars and oils. I desire to express my thanks to Dr. Knight for his TWO SIMPLE FORMS OF GAS PRESSURE By EDGAR STANSFIELD, M.Sc. SOME years ago, when working at the Sunderland Technical I. An outer vessel; such as a battery jar or widemouthed bottle. 2. An inner cylinder, open at the bottom and top; this may consist, as in Fig. 1, of a cylindrical vessel with one or more holes drilled through the sides near the bottom, or, as in Fig. 2, of a wide-mouthed glass bottle with the bottom cut off. A piece of wide glass tubing could be used. * A Paper read before the Faraday Society, May 2, 1911. 3. A float; a flask, test-tube, or beaker may be used, | weighted at the bottom to cause it to float upright. A beaker, as shown in both figures, gave the best results; the rim of the beaker should be an easy fit inside the cylinder. 4. Gas inlet and outlet tubes. 5. A valve connected to the float. In model A this valve consists of a small bulb blown at one end of a glass tube, the other end of which is fixed in a cork in the neck of the beaker float; the valve seating is a short bit of glass tubing; if the end of this tubing is first made square by rubbing on emery cloth, a very few minutes' grinding of the valve on its seating will then make it almost air-tight. The arrangement of the valve-seating in a cork in a slightly wider glass tube, connected at one sistent with free movement. A piece of glass tube with a cork in it, in which the rod is fixed, will furnish a suitable cap. The working of the regulator is virtually the same as with model A ; in practice the valve would, as a rule, be slightly lower down than is shown in the figure. In constructing a regulator, unless the inner vessel and accessories are heavy, they should be fixed in the cork of the outer vessel as in Fig. 2, otherwise the buoyancy due to the gas displacing water will cause them to upset. The area of cross-section of the float should be large compared with that of the valve, in order that the pressure exerted on the top of the valve by the inlet gas should be negligible, otherwise a large excess of inlet over outlet pressure may cause the valve to close and remain closed. Of the two types, A gives a very constant pressure, and if the valve is well ground the flow can be reduced almost end with the gas supply pipe and at the other end passing through a cork in the cylindrical vessel, is obvious from the drawing. In setting up the apparatus, water is poured into the outer vessel; wben gas is passed through in the direction shown by arrows it meets with no resistance until the pressure of gas in the inner vessel causes the water level, and consequently the beaker, to sink, and so closes, or nearly closes, the valve. If the initial pressure is high enough, the pressure in the inner vessel, that is, the gas delivery pressure, will be maintained constant at an amount equal to the difference of water level in the two vessels when the valve is just closing. Pouring water into the outer vessel will give a higher pressure, taking it out will reduce it. In model B the inlet and outlet tubes have to be blown into a vertical tube; the valve is a glass rod fixed in the cork of the float at one end and having a cylindrical cap at the other which fits in the vertical tube as closely as is con FIG. 2. to nothing. Its disadvantage consists in the fact that a sudden change of flow may set up a vibration which will keep on more or less indefinitely. In ordinary use with a gas oven, for example, this rarely or never occurs; it could probably be obviated by a slight modification of the shape of the valve. Model B has a less positive cut-off of the gas, so that it does not give such a constant pressure as A, and the flow of the gas cannot be reduced below the point where it becomes comparable with the leak past the valve; but for a large flow of gas where an absolutely constant pressure is not required, as, for example, for a combustion furnace, it gives very satisfactory results, and it never vibrates like model A. For any definite flow the pressure remains constant, but an increase of flow will slightly decrease the pressure. Mines Branch, Department of Mines, |