Organic analysis

1921 The Analyst  
Hubbard. (J. Bid. Chem., 1920,43, 43.)-The method adopted by the author is a modification of the one originally used by Messinger. Stock soIutions of iodine in potassium iodide and of sodium thiosulphate are prepared, 1 C.C. of each being equivalent to 1 mgrm. of acetone, Water free from Bmrnonia and other volatile matters is used for diluting these solutions to A, &, or & of their original strength, and additional potassium iodide is added to the dilute iodine solutions to make the
more » ... n of this salt approximately 3 per oent. These dilute solutions do not remain constant in otrength for more than two days. To 50 or 100 C.O. of the acetone solution a known amount of iodine solution is added, the quantity and strength used depending upon the amount of acetone expected to exist in the solution, but in m y case excess of iodine must be used. To the mixed solutions 2 0.0. of sodium hydroxide solution (200 grms. sodium hydroxide in 300 0.0. of water) are added, the mixture shaken, and allowed to stand ten minutes or longer, when 1 or 2 C.C. of 60 per oent. sulphurio acid is added, and the solution titrated with A s or other known atrength of sodium thiosulphafe, using starch solution as indicator. Since the solutions to be estimated may contain substances, such as alcohol, liable to vitiate the rssultrr obtained by the above method, the author has worked out met'hods depending upon oxidation by sodium peroxide, sulphuric acid, and potassium permanganete or potassium diohromate, whioh destroy these substances, while the acetone presenb is unaffeoted. The results obtained by the above method &re in good agreement with the aotual amount of acetone present in aqueous solution. T, J. W. Estimation of Acetone in Expired Air. R. S. Hubbard. (J. Biol. Chew., 1920, 43, 57.)-The anbject, fitted with a mask provided with an inlet vdva for inhaled air, expired €or ten minutes through two bcittlee arranged in series, eaah ounf&ning 75 C~O . 01 frwh 8.6 per cent. sodium bisulphite solution. Ten C.O. of 10 per cent. sodium hydroxide were added to, each bottle, and the contenta of ewh separately were washed into a Kjeldahl flaek. The solution waa distilled far ten minutes into aeoond Kjeldithl flask containing water to give B final volume of about 150 To the distillate 5 0.0. of 60 per cent. sutphnric add and 0.2 grm. of potaesiarn permanganate were added, and the solubion again distilled to give about 100 C.C. of distillate. TQ this distillate 0 5 grm. of sodium peroxide were added, and the mixture didfilled into a little water to give a volume of from 50 to 100 0.01 The aoetone present in this find distillate w m determined by the methd given in the 19 preceding abstract or by the turbidimetric method, using the Scott-Wilson reagent (mercuric cyanide 10 grms., sodium hydroxide 180 grms., water 1,200 e.c,; the solution is shaken, and 400 0.0. of 0.1268 per cent, silver nitrate solution slowly .run in, after which the solution should be kept at least one day before use). Quantitative determinations made by the. above method show excellent agreement with the known amounts of acetone used.. Normal adults exhale from 0.14 to 0.91 mgrm. of acetone per hour, but in cases of diabetes and exophthalmic goitre the amount increases to 5.24 and 15.0 mgrms. respectively. T. J. W. Analysis of Aromatic Nitro Compounds by Means of Titanium Trichloride. F. L. English. (J. Ind. and Eng. Chem., 1920, 12, 994-997.)-Mononitro hydrocarbons are very resistant towards reduction by titanium trichloride, but the presence of positive or negative substituents, with the exception of chlorine, in the nucleus facilitates the reduction of the nitro group. Further, it would appear from the results of experiments carried out by the author that the position of the substituents with respect to the nitro group has no appreciable effect ; for instance, m-and p-nitroaniline are reduced with equal ease, as are o-and p-nitrophenols, o-and m-nitro-p-toluidines, and two of the nitrosaliaylic acid esters, whilst o-and P-nitrochlorobenzenes are about equally refractory. The essential point in the reduction is the excess of titanium trichloride used ; the final concentration, after the mixture has been boiled, should be not less than 25 O.C. of titanium trichloride solution per 100 C.C. of total solution. w. P. 5, Viscosity of Cellulose Ester Solutions. M. Deschiens. (Chem. Trade J. a d Chhem. Engineer, 1920, 67, 472.)-The determination of the viscosity of cellulose nitrate and acetate is of great importance, and the usual prooesses for measuring this property are unsuitable, became the evaporation of the solvent at the orifice of the viscosimeter leaves a film which blocks up the opening. The viscosimeter recommended is that of Ostwald, and is of a U-shaped pattern with the usual two bulbs, the base of the U, however, having right-angle bends. The standard for cornparison adopted by the Allied Aviation Services is the viscosity of glycerol of 3 0 ' BaumB, at 15' C., the value of which is fixed at 100. The instrument is calibrated by means of glycerol under these conditions while almost entirely immersed in a thermostat at 15' 0. If cellulose aaetate is the eater under examination, the solution should be composed of 6 grms. of this material (preferably dried at looo to 105' C.) and 100 grms. of eoetone, great care being taken to see that solution is complete before use; if necemwy, it may be cenfirifaged or f3ltered Working with a solution of this strength, it was found that the time of flow was thirty seconds as against 190 for glycerol, and as this 190 is taken as being the 100 standard, the viscosity of the sample (a) 30 where 5 = 15-79. CeIIdme acetates of different origins, when dissolved in acetone, show figures varying from 42 to 10-5, and if intended for mannfacture of aeroplane dopes, should lie bstwsan 10 and 30. Samples showing higher vieoosity are preferable for the manufaohre of plastic masses or celluloid.
doi:10.1039/an9214600018 fatcat:u2q4pr4ddzbjvbyk4oej4sezoi