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THE JOURNAL OF 1ND USTRIAL AND ENGINEERING CHEMISTRY
Vol. 13, No. 11
position of the dissolved substance will be identical with presence of soluble salts, a behavior exactly analogous to the that of the solid. Very conclusive evidence, however, was action of salts in catalyzing the hydrolysis of esters. brought out by the following experiment: Some tricalcium This explanation, of course, is a t variance with the asarsenate of the best purity was placed in a glass-stoppered sumption that tricalcium arsenate, since it is the most insolbottle, covered with distilled water containing a few drops uble, is therefore the most stable of the calciuq arsenates. of phenolphthalein, and shaken occasionally for several days. Insolubility is not an infallible index of stability, as might be A considerable alkalinity developed. To meet the objection shown by citing a number of cases in which insoluble substances that the alkalinity might be due to calcium hydroxide present are hydrolytically converted into more soluble ones. Magin the arsenate, this water was drawn off, and analysis nesium ammonium phosphate is a single example. From showed that it contained a corresponding amount of soluble this point of view, tricalcium arsenate in contact with mpisture arsenate. The water over a slightly impure sample (contain- is a metastable substance, and its transformation into the ing a trace of sodium chloride) reddened more rapidly than more stable secondary arsenate may be easily effected by many substances. in the case of the pure substance. This concept of a reversible hydrolysis also explains SUMMARY the other facts in the behavior of tricalcium arsenate. The 1-The most favorable conditions for making a stable stabilizing effect of the excess of lime is due to the repression of the hydrolysis. On the other hand, decomposition will be form of tricalcium arsenate that will have a low soluble arfavored by introducing anything that will combine with senate content and be otherwise suitable for use as an inthe calcium hydroxide formed, such as acidic substances secticide on plants are: (a) high temperatures, ( b ) purity or materials that will convert it into a more insoluble com- of materials, (c) excess of lime, (d) thorough mixing. 2-The water used in preparing sprays should be as pure pound. This is illustrated in the action of the tap water and of the ferrous sulfate (Table IV). The effect. of the sodium as possible. 3-The decomposition of tricalcium arsenate is due to chloride and calcium nitrate is probably of a different nature. The easiest and most direct explanation of such action is tfhat hydrolysis, which seems to be catalyzed by many substances the decomposition of tricalcium arsenate is catalyzed by the that may be present as impurities.
Preparation of Mannose from Ivory-Nut Shavings' By Paul M.Horton BATONROVQE,LOUISIANA AUDUBON SUQAR SCHOOL,LOUISIA+ STATE UNIVERSITY,
For a number of years it has been customary in the chemical laboratory of the Louisiana State University to assign to advanced students in the Audubon Sugar School the preparation of various rare sugars in the pure form. These preparations as a rule were not very satisfactory, either as to yield or product, nor wag it always easy to tell where the trouble lay. During the past few years the rare sugars, however, have been attaining considerable technical importance. The following description of the preparation of mannose presents our experience in an attempt toward its simplification. The procedure described has been tried out by six or eight students of average technique in organic chemistry with uniformly satisfactory results, both as to yield and quality. This procedure is presented not as offering anything essentially new, but in order that any one attempting to prepare this rather costly sugar may be assured of results. Though mannose occurs in many substances, the usual source is ivory-nut shavings, a by-product in the manufacture of buttons. A review of the literature will indicate that the source of the mannose produced from this source is largely the reserve mannocellulose. Whether the nuts actually contain fructo-mannan or not is immaterial, but it is certain that gums and other extractives are present, complicating the procedure by the steps needed for their removal. By the older processes the final sirup was always difficult to crystallize, owing to the various impurities passing through. For this reason the mannose was usually first separated as the hydrozone. Bourquelot and Herissey2 probably first described the method of hydrolyzing mannocellulose by means of cold 75 per cent sulfuric acid, but C. S. Hudson3 has recently much improved the procedure by crystallizing the sugar direct from 1 Presented before the Section of Sugar Chemistry and Technology a t the Blst Meeting of the American Chemical Society, Rochester, N. Y., April 26 t o 29, 1921. * Comfit. r e n d , 133 (19011, 302. 8 J . A m . Cirem. Soc., 39 (1917). 670.
glacial acetic acid, thus avoiding the use of the expensive reagent, phenylhydrazine acetate. The method finally adopted in our laboratory is as follows: Dissolve 20 g. of commercial sodium hydroxide in 2000 cc. of tap water and heat to boiling, preferably in a porcelsbin dish. Stir 175 g. of 20-mesh ivory-nut powder or shavings into the boiling solution and remove at once from the source of heat. Allow the mixture to stand for 1 hr. with frequent stirring. Filter off the deep brown extract, and wash the residue until the runnings are clear and neutral. This filtration can be carried out effectively in an 8-in. Buchner funnel with suction, using heavy toweling as the filtering medium. Theresidue is sucked dry and finally transferred to a tray and dried at room temperature or in an electric oven at not over 60" C . Mix 130 g. of the absolutely dry residue with 130 g. of cold 75 per cent sulfuric acid (1000 g. of 1.84 acid plus 400 cc. water for stock). If the residue has been well dried there will be very little evolution of heat, and the absence of irritating vapors is especially noticeable as contracted with the results obtained when using the unextracted shavings. The heavy, brownish, dough-like mass may be allowed to stand indefinitely without much decomposit,ion, although 6 hrs. are sufficient for the reaction. Dissolve the mass in water to obtain a final volume of about 1.5 liters. Heat t o boiling and allow to simmer for at least 6 to 8 hrs., keeping the volume constant by adding water from time to time to replace evaporatiqn. A reflux may be used. At the end of this period there will still remain a brownish residue in the solution, consisting for the most part of the outer skin of the nuts, which will weigh not over 10 g. when dry. Without filtering, allow the solution to cool to room temperature. Prepare a creamy solution of calcium hydroxide by slaking 50 g. of freshly burned lime in about 300 cc. of warm water. When cold add to the mannose solution with violent stirring and agitation in order that no, portion
Nov., 1921
THE JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
of the liquid may become alkaline, even temporarily. Filter combined precipitate of calcium sulfate and dissolved nut residue on cloth, without warming. The cake will be found very porous and easily washed. Heat the filtrate, which should be still faintly acid, to about 90" C. and add 10 g. of Norit or some other decolorant char. Cool, add an excess of pure precipitated chalk or barium carbonate, and again filter on cloth. The precipitate, consisting of the excess carbonate and char along the sulfate, will wash easily. The filtrate should be perfectly clear and must not change the color of either red or blue litmus. Evaporate under vacuum to a light sirup (150 to 200 cc.). Considerable inorganic matter (mostly calcium sulfate will crystallize out a t this point. Pour the cloudy sirup into a n equal volume of 95 per cent ethyl alcohol, heat to about 90" C., add 3 g. of Norit, and filter hot. Wash with 70per cent alcohol, which neither precipitates sugars nor dissolves inorganic salts. This liquor will be almost water-white. Again. evaporate under high vacuum to an almost solid mass (96 per cent solids by refractometer), the last portion of the water being expelled with the water bath at about 85" to 90". This is necessary to prevent overheating of the sirup, which will give a yellow color to the mass. When the water is practically all evaporated the sirup will commence to boil as a whole and will become a mass of bubbles. If it is removed from the source of heat, the sirup will collapse to the bottom of the flask in strings. The mass will flow only slowly if the boiling vessel is inverted. This amount of detail is given as it is important that the boiling be carried to the right point, and a refractometer is not always available.
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Finally add an equal volume of warm glacial acetic acid and dissolve by warming and shaking. The sugar will go into solution rather slowly and in some cases it may be necessary to add 1 or 2 cc. of water as a last resort. Pour into a covered crystallizing dish and allow to stand for 24 hrs. before seeding. The sirup will crystallize within 3 days without seeding if the preparation is carried out carefully. Add small portions of acid (totaling 50 cc.) as crystallization proceeds. If after 2 days no crystallization occurs, place the dish in a freezing mixture and freeze solid, stirring as long as possible. After thawing, out crystals will probably appear a t once. As a last refiort in obstinate cases, dilute with 400 cc. of water and reboil to a heavier sirup. I n any event the acetic acid solution should be practically colorless. Filter the mannose crystals on paper with suction, washing in succession with glacial acetic acid, alcohol and acid, pure alcohol, alcohol and ether, and finally with pure ether. The crystals niay now be transferred to a mortar and ground with ether and refiltered. The sugar is pure white and needs no further purification for ordinary purposes. Dry a t 40" C. until absolutely fluffy and free from odor. The yield is about 40 g. The sugar has a sweet taste, followed by a bitter aftertaste. It will be noticed that this method eliminates the use of lead subacetate and treatment with hydrogen sulfide, avoiding several difficult filtrations. Furthermore, it will be observed that the sirup will not assume a gelatinous consistency upon boiling down, thus indicating that gums and extractives are absent.
Comparison of Results in Desugarization with the Steffen Lime, Barium, and Strontium Processes' By Mich. Potvliet DOMINION SUGAR Co., CRATHAM. ONTARIO,CANADA
As the scarcity of granulated sugar has made i t possible to make large profits in the desugarization of beet molasses by means of the Steffen lime process, the latter procedure has shown very few improvements in its practical execution during the past years. The only improvement of importance consists in the possibility of grinding the burned lime to such a fineness as to permit a more easy and complete formation of saccharate and a greater saving of lime. A second improvement in the Steffen process has been the saving of the wmte water or mother liquor. The war made it necessary to use every possible substitute for the potash which had been imported from Germany, and in some factories the wmte waters from the Steffen house were evaporated, after the excess of lime compounds had been removed, for the purpose of recovering the potash. The process of concentrating this very dilute waste water was expensive and, owing to trouble with lime compounds, it was practiced in only a few factories. As soon as the market for potash is reestablished, v7e may assume that the Steffen waste water will flow into the sewer as in former days. About fifteen years ago an Italian chemist, Bat,tistoni, used the barium oxide which he obtained in electric furnaces for the formation of barium saccharate. The juices from this saccharate apparently had many advantages over those of the Steffen lime process. The strontium bisaccharate has lately attracted attention. This process has been used for many years in several factories in Germany, among which the factory a t Dessau is the most f Presented before the Section of Sugar Chemistry and Technology at the Glst Meeting of the American Chemical Society, Rochester, N. Y., April 26 t o 29, 1921.
important. The juices from this process also show marked advantages over the lime method. The writer proposes to compare these three processes of desaccharification. If barium oxide and strontium oxide can be made more cheaply than a t present, there is no doubt in the writer's mind that the Steffen lime process in the near future will be doomed.
EXPERIMENTAL I n order to compare the three methods, a molasses was worked with which had the following constant composition in all experiments: Brix Polarization Sugar Raffinose
84.5 51.1 48.5 1.2
Raffinose on 100 polarization Apparent purity Real purity
2.35
GO. 50 57.40
In the discussion that follows, polarization always means the direct polarization, and sugar represents the real sugar after deducting raffinose. Furthermore, the final results of this paper are all based upon real sugar. The lime used in the lime process was obtained by burning limestone in the ordinary vertical limekilns and was usually of a high grade. The barium oxide, used for making the solution of hydroxide, was obtained by the reduction of barium carbonate. The most complete reduction is obtained in an electric furnace, where the constant temperature and exclusion of gases from the oxide permit a yield of oxide as high as 95 per cent. The strontium oxide was obtained by reducing moist stroiitium carbonate, mixed with sawdust or powdered oil-cake, in a so-called cement kiln, which is a horizontal rotary kiln using fuel oil as a source of heat.
