摘要:

JANUARY 1924. Vol. XLIX. No. 574. THE ANALYST PROCEEDINGS OF THE SOClETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. AN Ordinary Meeting of the Society was held on Wednesday December rith at the Chemical Society’s Rooms Burlington House. The President Mr. P. A. Ellis Richards F.I.C. was in the chair. Certificates were read for the first time in favour of :-Messrs. Frank Knowles, Archibald Knox A.I.C. Charles Roger Middleton B.Sc. A.R.C.Sc. D.I.C. A.I.C., Harold Richard Read A.I.C. George Hogan F.I.C. and Thomas Francis Doyle. Certificates were read for the second time in favour of:-Messrs. Robert Charles Frederick and Hubert Thomas Stanley Britton M.Sc. (Lond.) F.I.C. The following were elected Members of the Society :-Mews. Laurence Eversley Campbell fi1.S~. (Lond.) F.I.C. John Troubridge Hannen B.A. (Cantab), A.R.C.Sc. A.I.C. Cyril Langley Hinton F.I.C. Douglas William Kent- Jones, 1 3 5 . (Lond.) F.I.C. Thomas William Alan Shaw M.Sc. (Liv.) William Hall Simmons A.I.C. Kenneth Edward Nethercoate Williams and Percy Noel Williams, M.Sc. (Liv.) A.I.C. The following papers were read :-“ Crystalline Bromides of Linseed Oil,” by Harold Toms M.Sc. (under the Analytical Investigation Scheme) ; “The Plea for Standardisation,” by M. S. Salamon B.Sc. ; “ Note on the Estimation of Chromium,” by Hubert T. S. Britton M.Sc. F.I.C. ; and “The Colorimetric Estimation of Lead in Cream of Tartar,” by R. 1,. Andrew

ISSN:0003-2654    

DOI:10.1039/AN9244900001

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

2 HINTON AND MIACARA THE APPLIC.4TION OF THE IODIMETRIC The Application of the Iodimetric Method to the Analysis of Sugar Products. BY C. L. HINTON F.I.C. AND T. MACARA F.I.C. (Read at the Meeting October 3 1923.) DURING thc last few years the iodimetric process for Ihe estimation of reducing sugars has been examined by a number of investigators the chief of these being Willstatter and Schiidel (Bey. 1918 51 780; ANALYST 1918 43 416); H. M. Judd (Biochem. J . 1920 14 255; ANALYST 1920 45 224); Baker and Hulton (Biochem. J. 1920 14 754); and Cajori ( J . Biol. Chewz. 1922 54 617 ; ANALYST, 1923 48 73). The process consists essentially in adding a known amount of standard iodine solution to a given quantity of the dilute sugar solution rendering the mixture alkaline and allowing i t to stand for a short time then re-acidifying and titrating the excess of iodine with standard thiosulphate solution.In most cases sodium hydroxide is used for making the solution alkaline though Cajori prefers sodium carbonate as being less likely itself to affect the sugars. As will be seen quite definite results can be obtained with sodium hydroxide and this has been used in the present experiments. A few experiments on the effect of other alkalis are however described at the end of this paper. ‘The alkali should always bc added after the mixing of the sugar and iodine solutions. The whole series of operations is carried through quite rapidly and with a minimum of apparatus and reagents which are readily available in any laboratory, so that the process recommends itself admirably for factory analysis.Unfortu-nately the statements as to the extent to which the different sugars are oxidised by the alkaline iodine solution are not altogether in agreement and it was as an attempt to clear up these points and to place the iodimetric analysis of sugar mixtures on a sound basis that the present work was carried out. , GENERAL EXPERIMENTAL PROCEDURE.-The required amount of sugar solution was measured into a 250 C.C. conical flask and made up to approximately 50 C.C. with distilled water; 40 C.C. of 0.05 N iodine solution were then added, followed by the required amount of 0.5 N sodium hydroxide solution and the flask stoppered. After standing for the time required the mixture was acidified with 5 C.C. of 2 N sulphuric acid and immediately titrated with 0-05 N thiosulphate solution accurately standardised against pure potassium iodate.Starch was used for the end-point. In all cases one or more blank experiments in which distilled water was used in place of the sugar solution were carried out a t the same time and under the same conditions as each series of experiments, (See also note a t end. METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 3 I. DEXTROSE. Most observers find a quantitative oxidation of dextrose to gluconic acid by alkaline iodine according to the equation : C,HI20 +I2 f3NaOH =C,H,,O,COONa +2NaI +2H,O. 1 grni. of dextrose should therefore require 1.410 grm. of iodine for oxidation. Miss H. M. Judd however reports finding only 1-315 grin. iodine required per 1 grm.of dextrose and concludes that the oxidation of dextrose is never complete though a definitc and constant weight of iodine always reacts with a given weight of dextrose. PRELIMINARY EXPERIMENTS.-sOme preliminary work to fix the experi-mental conditions was carried out on a sample of nearly pure commercial dextrose. This material gave the following analytical figures :-Moisture 2.52 per cent. ; [a] (15 per cent. concn.) +51.0"; [aID on dry basis = +52.3". Variation in Amount of Alkali Used.-A 0.2 per cent. solution of the dextrose was prepared and quantities of 40 c.c. made up to 50 C.C. before adding the iodine were used for each titration. Varying quantities of 0.5 N soda were then added the flasks stoppered and the solutions allowed to stand at room temperature for 10 minutes; 5 C.C.of 2 N sulphuric acid were then added and the solutions at once titrated. 11. (a) The results are collected in Table I. TABLE I.-EFFECT OF VAlClATlON I N AMOUNT 01; ALKALI USED. Aiiiount. o f sugar in cach titration - 0.08 g r i . 1 line of reaction --lo minutes. Blank titration --38.13 C.C. of 0-05 N tliiosulyliate solution. r Nc 1 2 3 4 5 6 7 Sodium hydroxide (0.5 N) solution. C.C. 3 4 c i 7 9 10 3 Thiosulyhate (0.05 N ) solution. C.C. 25-12 22.14 21-06 22.02 22-14 22.72 63-13. Iodine (0.05 N ) solution reduced. 14.01 16.99 17.17 17.11 16-99 16-41 16 -00 C.C. Iodine per 1 grm. of sugar. Grms. 1.112 1 *348 1.362 1 -357 1 -348 1 -302 1 a270 In No.1 the amount of sodium hydroxide is obviously deficient. No. 3, where 5 C.C. of 0.5 N sodium hydroxide solution were used gives the maximum iodine value for the sugar. In this case the ratio of iodine to sodium hydroxide in terms of normal concentrations is 1 :1-25 and this amount of sodium hydroxide appi-oxiiiiatcly correspoiids to the amount necessary for the iieutralisatioii of tli 4 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC gluconic and hydriodic acids formed by oxidation of the sugar with sufficient excess for the formation of hypoiodite with all the excess of iodine: I f2NaOH =NaOI +NaI -t-H20. Alkali in excess of this amount diminishes the apparent iodine value of the dextrose, just as does a deficiency. Even a ratio of l:l.Fi as shown by No.4 shows a slightly low value although this is the proportion usually recommended. This would theoretically be the amount of sodium hydroxide required if the whole of the iodine entered into the glucose reaction (given by first equation above) but as in practice at least half of the iodine is unattacked a certain slight excess of alkali must be present if the ratio 1 :1-5 is maintained. Proportions of Dextrose to lodine.-In this series varying amounts of dextrose solution were measured out made up to 50 c.c. and the iodine and sodium hydroxide added. For Nos. 1 to 5 G C.C. of sodium hydroxide solution were used; for the others 5 C.C. The results given in Table II. show that provided not more than about half of the total iodine is used up the proportion of dextrose to iodine does not affect the result.Obviously it is an advantage to work with as large a quantity of sugar as possible whilst remaining within safe limits. A suitable amount would be 0.08 grm. dextrose for 40 C.C. of 0-05 N iodine. (b) The time of reaction was 10 minutes. TABLE 11.-EFFECT OF VARYING EXCESS OF IODINE USED. Time of reaction:-10 minutes. Blank titration :-39.13 C.C. 0.06 N tlliosulphate solution. lodine 'I'hiosulphate (0.06 N ) Iodine No. Grm. C . C . C.C. Grms. (0.05 N ) solution per 1 grni. Dextrose. solution. reduced. of sugar. 6 C.C. of 0.6 iV NaOH used. 1 0.02 34.86 4.27 1.355 2 0.04 30.55 8.58 1 *36l 3 0.06 28.42 10.7 1 1-359 4 (b*O!3 22 -07 17-06 1.363 5 a m 22 -02 17.11 1 -357 6 0.08 21.96 17-17 1 *362 9 0.10 17 -78 21.36 1 *355 8 0.12 13-95 25.18 1 *332 5 C.C.of 0.5 N NaOH used. (G) Time of Reaction.-Willstatter and Schiidel recommend that 12 to 20 minutes be allowed €or the reaction to take place. Baker and Hulton state that 3 to 5 minutes suffice. From the experiments detailed in Table III. in which varying periods were used it would appear that 5 minutes may be in-sufficient in the case of dextrose. There appears however to be no appreciable action after 10 minutes METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 5 TABLE 111.-EFFECT OF TIME OF REACTION. Amount of sugar in each titration:-O.OS grm. Blank titration:-39.13 C.C. of 0.05 N thiosulphate solution. No. Time. 6 C.C. of 0.5 N NaOH. 1 5 mins. 2 10 ,, 3 2o > J Thiosulphate (0-05 N ) solution.required. C.C. 22 -57 22 -02 22 -05 Iodine (0.05 N ) Iodine solution per 1 grm. reduced. of sugar. C.C. Grms . 16.56 1.314 19.11 1 -357 17 *08 1.355' 5 C.C. of 0.5 N NaOH. 4 10 2 21 -96 17.17 1 -362 5 20 1 ) 21 -94 17-19 1 0364 (a) Concentration of Reacting Mixture.-For this purpose a 0.8 per cent. solution of the dextrose was prepared and in each case 10 C.C. were accurately measured out and made up with distilled water to the required volume. The results in Table IV. show slightly higher figures for Nos. 1 2 and 5. This is probably due to slight loss of iodine by volatilisation from these more concentrated mixtures. The total volume of reacting solutions should conveniently be about 100 C.C. per 40 C.C. of 0.05 N iodine used.Nos. 5 6 and 7 are the results of an attempt to ascertain whether increasing the dilution of tfle solution had any effect on the influence of an excess of alkali in diminishing the iodine value; this does not appear to be the case. TABLE 1V.-EFFECT OF CONCENTRATION OF SOLUTION. Amount of sugar in each titration:-O-08 grm. Blank titration :-38.68 C.C. Time of reaction:-10 minutes. VOl. of sugar solution. No. C.C. 5 C.C. of 0.5 N NaOH. 1 10 2 30 3 50 4 70 Thiosulphate Total (0.05 N ) vol . solution. C.C. C.C. 55 21 *35 75 21-38 95 21 *41 115 21 -41 Iodine (0-05 N ) solution reduced. C.C. ' 17 *23 17 *20 17-17 17.17 Iodine per 1 grm. of sugar. Grms. 1 *367 1 0365 1 -362 1 -362 8 C.C. of 0.5 N NaOH.5 30 78 22.10 16.48 1 -308 6 50 98 22.14 16-44 1 *304 7 70 118 22.13 16-45 1 -30 6 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC B. IODINE REDUCING POWER OF PURE DEXTRosE.-The commercially pure dextrose used above was recrystallised from dilute alcohol the first crop of crystals being rejected and only the middle crystallising portion of the sample being retained. This was washed on a Buchner funnel with 70 per cent. alcohol absolute alcohol and ether and dried initially at 45" C. with gradual raising of the tem-perature to 95" C. About 10 per cent. of the original dextrose was thus recovered, which gave the following figures on analysis:-Moisture (105" C.) 0.21 per cent.; ash 0.07 per cent.; [GI? consi. (5 per cent. solution) +52.67" C.; on dry basis = +52*78" C.) For the determination of the iodine value a 0-8 per cent.solution of this dextrose was prepared and 10 C . C . accurately measured out and made up to 50 C.C. before adding the 40 C . C . iodine solution; 5 C . C . of 0.5 N sodium hydroxide solution were used and the time of reaction was 10 minutes. The results are shown in Table V. ; Nos. 2 3 and 4 were carried out on a different solution and on a different occasion from No. 1. It will be seen that the average iodine reduction for this sample is 1.406 grms. per 1 grm. of sugar which corresponds to a value of 1.410 grms. for dry ash-free dextrose. The accuracy of a single determination appears to be about k0.2 per cent. This is the theoretical value. TABLE V.-IODINE REDUCING POWER OF DEXTROSE.Amount of sugar in each titration:-O.08 grm. Amount of alkali in each titration:-5 C.C. of 0.5 N NaOH. Time of reaction:-10 minutes. Blank titration. Thiosulphate (0.05 N) solution. No. C.C. 1 39 -50 2 39.21 3 ,, 4 9 , Back titration. Thiosulphate (0.05 N) solution. 21.79 2 1 -45 21.51 21 -47 C.C. - on dry Iodine (0.05 N) Iodine solution per 1 grm. reduced. of sugar. C.C. Grms. 17-71 1 -405 17.76 1 -409 17.70 1 -404 17 074 1 -407 Average 1 0406 ash-free basis 1.410 --In order to verify the experiments already carried out on the commercial dextrose as to the influence of varying excess of iodine a series of titrations was carried out with the use of varying proportions of dextrose to iodine (Table VI.).Nos. 1 and 2 were made in the usual way outlined above; the others were done b METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 7 measuring out arbitrary quantities of dextrose solution making the liquids up to 100 C.C. and using 40 C.C. of 0.1 N iodine solution and 10 C.C. of 0.5 N sodium hydroxide solution. TABLE V1.-EFFECT OF VARYING EXCESS OF IODINE. Nos. 1 and 2 carried out with 40 C.C. of 0.05 N iodine + 5 C.C. of 0.5 N NaOH. Others with 40 C.C. of 0.1 N iodine + 10 C.C. of 0.5 N NaOH. Time of reaction:-10 minutes. Dextrose. NO. Grms. 1 0.0500 2 0*0500 3 0.05087 4 0.0846 5 0 1245 6 0.1472 Within the range of Back Blank. titration. Iodine Thiosulphate Thiosulphate (0.05 N ) Iodine (0.05 N ) (0.05 N ) solution per 1 grm. solution. solution.reduced. of sugar. C.C. C.C. C.C. Grms. 39.38 28-31 11 *07 1 -405 Y 28.30 11 -08 1 -406 82-00 70.74 11 -26 1 -405 ,> 63 -2 1 18-79 1 *409 J > 54-43 27-57 1 -405 8 49.31 32.69 1 0409 Average 1 =406(5) proportions used there is no appreciable difference whether a smaller or larger amount of dextrose be taken. It must be noted, however that in all these cases there is an excess of iodine greater than the total amount reduced. The average figure practically agrees with that of the previous series with about the same degree of accuracy. In view of the ease with which dextrose is quantitatively oxidised by alkaline iodine it is difficult to account for Miss H. M. Judd's statement that the reaction is never complete. 11. LACTOSE. A sample of pure milk sugar (lactose hydrate) was used with the following (a) Variation in Amount of Alkali-A 0.4 per cent.solution was prepared, 40 C.C. being used for each titration and made up to 50 C.C. before the iodine was added. Amounts of 0.5 N sodium hydroxide solution varying from 3 to 8 C.C. were used ; the reaction time was 10 minutes. Table VII. shows that the maximum iodine consumption occurs when the ratio of iodine to sodium hydroxide is 1 :lo13 to 1 :1.25. In these cases the alkali is approximately the amount required for the neutralisation of the sugar acid and hydriodic acid found and formation of hypoiodite with the excess of iodine as was found in the case of dextrose. analysis:-Moisture 0.025 per cent.; ash 0.065 per cent.; [a]g (c =5) +52.3" C 8 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC TABLE VI1.-LACTOSE.EFFECT OF VARYING PROPORTIONS OF ALKALI. 1 No. 1 2 3 4 5 6 7 Amount of sugar in each titration:-O.16 grm. Time of reaction:-10 minutes. Back Sodium Blank. titration. Iodine hydroxide Thiosulphate Thiosulphate (0.05 N) (0.05 N) (0.05 N) (0.05 N ) solution solution. solution. solution. reduced. C.C. C.C. C.C. C.C. 3 39 ~ 0 5 26-13 12.92 4 39.09 22-00 17-09 4.5 39 *09 21.31 17.78 5 39-05 21-37 17 -68 6 39-05 21.77 17 *28 7 39 *09 22 *33 18-76 8 39 -05 23-02 16-03 Iodine per I grm. of sugar. Grms . 0.512 0.678 0.705 0.701 0-685 0 *665 0.635 (b) Proportions of Lactose to Iodine.-Table VIII. shows the results for lactose when the proportion of sugar is varied the iodine and alkali being kept constant.As with dextrose there is no appreciable effect due to the amount of sugar provided there is an excess of iodine a t least equal to the amount reduced. In No. 5 the amount of iodine is obviously deficient. A convenient amount of lactose to use would appear to be 0.16 grm. per 40 C.C. of 0.05 N iodine. TABLE VII1.-LACTOSE. EFFECT OF VARYING EXCESS OF IODINE. Amount of alkali used:-5 C.C. of 0-5 N NaOH. Time of reaction:-10 minutes. Blank titration:-39.05 C.C. of 0.05 N thiosulphate solution. Back titration. Thiosulphate (0-05 N) Sugar. solution. No. Grms . C.C. 1 0 -04 34-83 2 0908 30.16 3 0.10 27 *98 4 0.16 21 -39 5 0.20 17 *69 Iodine (0.05 N ) solution reduced. 4.42 8.89 11 -07 17.66 21 *36 C.C.Iodine per 1 grm. of sugar. Grms . 0.701 0-704 0.703 0.701 0.678 (c) Time of Reaction.-The few experiments recorded in Table IX. show that with lactose as with dextrose 5 minutes appears to be rather insufficient for the completion of the reaction. On the other hand No. 3 points to the possibility of a reduction of iodine beyond the theoretical value if the time is prolonged; but the present experiments are perhaps inadequate to decide this point. Lactose hydrate should have an iodine reducing power of 0.705 grm. of iodine per grm. corresponding to 0.743 grm. for anhydrous lactose. Miss H. M. Jndd’s figure of 1.502 and even that of Baker and Hulton (0.762) for anhydrous lactose are higher than the figures found in these experiments which show no reason for supposing that the theoretical figure does not hold good for the conditions arrived at here METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 9 TABLE 1X.-LACTOSE.EFFECT OF TIME OF REACTION. No. 1 2 3 Amount of sugar in each titration:-O.16 grm. Amount of alkali:-5 C.C. of 0.5 N sodium hydroxide solution. Blank titration :-39.09 C.C. of 0.05 N thiosulphate solution. Back titration. Iodine (0.05 N ) solution per 1 grm. solution. reduced. of sugar. Thiosulphate (0.05 N ) Iodine Time. C.C. C.C. Grms. 5 min. 21.57 17-52 0.695 10 ,) 21 *41 17-68 0-701 20 ? 2 1 *22 17.87 0-709 111. SUCROSE. There is some disagreement in the statements as to the behaviour of sucrose with alkaline iodine. Willstatter and Schiidel found no oxidation whilst Miss Judd found 0.006 grrn.of iodine reduced per 1 grm. of sucrose and Baker and Hulton found 0.02 grm. per grm. of sucrose; both thesk figures were obtained, however on amounts of 0.1 grm. of sucrose and therefore with very small amounts of iodine taken up. The sucrose used in the following experiments was a sample of pure sucrose supplied by Messrs. Tate for standardisation purposes. It contained 0.01 per cent. of moisture and 0.008 per cent. of ash and polarised + 66.55" at 16' C. and a t a concentration of 20 per cent. E8ect of Varying Proportions of Alkali.-The sucrose was finely powdered and weighed out separately for each titration; it was dissolved in 50 C.C. of water, and the iodine and alkali added as usual The time was kept at 10 minutes.As will be seen from Table X. the amount of alkali appeared to have little influence, even when as much as 20 grms. of sucrose was used. (a) TABLE X.-SUCROSE. EFFECT OF VARYING PROPORTIONS OF ALKALI. Amount of sugar in each case:-20 grms. Time of reaction :-lo minutes. Blank titration :-38.90 C.C. of 0.05 N thiosulphate solution. Back titration. Thiosulphate (0.05 N ) No. C.C. C.C. 1 3 31.96 2 5 31 -32 3 8 30.78 0.5 N NaOH solution. Iodine (0-05 N) Iodine solution per 1 grm. reduced. of sugar. C.C. Grms. 6.94 0.0022 7 -58 0.0024 8.12 0*0026 (b) Eeect of Varying Proportions of Sucrose to Iodine.-Experiments in which different amounts of sucrose for the same amount of iodine were used showed that the iodine reduction is not strictly in proportion to the sucrose used.Ther 10 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC is a slight falling off with increasing amounts of sucrose as Table XI. shows This at once precludes the possibility of the reduction being due to traces of dextrose; for if this were so the reduction should be practically proportional to the sugar used. TABLE X1.-SUCROSE. EFFECT OF VARYING PROPORTIONS OF SUCROSE TO IODINE (1). Amount of alkali used:-6-5 C.C. of 0.5 N NaOH. Time of reaction :-lo minutes. Blank titration:-39-06 C.C. of 0.05 N thiosulphate solution. Back titration. Iodine (0.05 N ) solution per 1 grm. reduced. of sucrose. Thiosulphate (0.06 N ) Iodine Sucrose. solution. No. Grms. C.C. C.C. Grm. 1 2 37 -83 1 -23 0 -0038 2 5 36.40 2-66 0 moo34 3 10 34.18 4088 0.0031 4 15 32 -30 6-76 0 -0029 5 20 30 *42 8-64 0.0027 I t appeared probable that the lower iodine reduction with the larger amounts of sucrose might be connected with the smaller excess of iodine.In order to examine this point additions of 0.08 grm. of the dextrose used in Tables I. to IV. were made to two quantities of 4 and 8 grms. of sucrose. To allow sufficient iodine 50 C.C. of 0.05 N iodine solution were used in these cases with 6-25 C.C. of 0.5 N sodium hydroxide solution. From the amounts of iodine reduced were deducted the amounts due to the dextrose and the difference gave the iodine value of the sucrose used. As anticipated the figures were rather lower than when no dextrose was used though not so low as might have been expected if the whole of the used-up iodine had been reduced by sucrose.(Table XII.) TABLE XI1.-SUCROSE. EFFECT OF VARYING PROPORTION OF SUCROSE TO IODINE (2). 0.08 grm. commercially pure dextrose (Table I.) present in each case. Iodine equiv. :-17.17 C.C. of 0.05 N iodine solution. Amount of alkali used:-6.25 C.C. of 0.5 N NaOH. Time 10 minutes. Blank titration 49.38 C.C. Back ti tration. Iodine Less (0.05 N ) solution due to per 1 grm. Sucrose. solution. reduced. dextrose. of sucrose. Thiosulphate (0.05 N ) amount Iodine No. Grms. C.C. C.C. C.C. Grm. 1 4 30 *34 19 -04 1 437 0*0030 2 8 28-83 20 *55 3.38 0 -0027 (c) E8ect of Temperature.-Certain irregularities in the figures so far obtained for sucrose (e.g. compare Table X. with No.4 of Table XI.) led to an investigation into the effect of temperature on the reaction since it might be expected that here, dealing with a very incomplete oxidation the temperature might considerably influence the extent to which the oxidation proceeded METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 11 For this series the sucrose was dissolved in water and the temperature adjusted by means of a bath; the iodine and alkali were then added (at room temperature) and the mixture agitated in the bath for 3 minutes and allowed to stand in the bath for the remaining 7 minutes. TABLE XII1.-SUCROSE. EFFECT OF TEMPERATURE. Amount of sugar in each case:-20 grms. Amount of alkali:-5 C.C. of 0-5 N NaOH. Blank titration :-39.91 C.C. of 0.05 N thiosulphate solution. Time:-10 minutes.Back ti tration. Iodine (0.05 N ) solution per 1 grm. Thiosulphate (0.05 N ) Iodine Temperature. solution. reduced. of sugar. 1 15 30-73 9-18 0*0029 2 22-5 25 -42 14-49 0 *0046 3 30 21-40 18-51 0.0059 No. O c. C.C. C.C. Grm. The results (Table X1II.) showed a considerable increase of iodine reduction due to increased temperature; the iodine value at 30" C. was double that at 15" C., with an intermediate value at 22-5" C. Accordingly for further experiments on sucrose a standard temperature of 17.5" C. (the most suitable at the time this work was carried out) was adopted. ( d ) Efiect of Time ofReaction.-For the reason given in the preceding section, it might be expected that the reaction of sucrose with alkaline iodine would proceed much further when the time was prolonged.The point was investigated by allowing quantities of 10 grms. to react for increasing periods of 10 minutes 4 hour, and 2 hours with a blank in each case standing the same length of time. There was a rapid increase of reduction in the first half-hour the rate of which however, fell away considerably in the succeeding 18 hours. A fourth mixture was then prepared and allowed to stand for 3 days at 17.5" C. There was no further increase although the excess of iodine was considerable. The four experiments are recorded in Table XIV.; it appears that a maximum value for the iodine reduction is reached after about 2 hours to the extent of 0.0067 grm. o€ iodine per 1 grm. of sugar. TABLE XIV.-SUCROSE. EFFECT OF TIME OF REACTION. Amount of sugar in each case:-10 grms.Amount of alkali:-5 C.C. of 0-5 N NaOH. Temperature:-17-5" C. Back Blank. titration. Iodine Thiosulphate Thiosulphate (0.05 N ) Iodine (0.05 N ) (0.05 N ) solution per 1 grm. solution. solution. reduced. of sugar. No. Time. C.C. C.C. C.C. Grm. 1 10 mins. 40-16 35-17 4.99 0.0032 2 30 mins. 40.14 30.90 9-24 0.0059 3 2 hrs. 40 12 29-48 10.64 0.0067 4 3days 40.14 29.63 10.51 0.006 12 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC (e) Iodine Reducing Power of Sucrose.-From the data given in Tables X. to XIV. it is possible to obtain a value for the reducing power of sucrose under the conditions of the standard procedure. This procedure as originally outlined, must now be modified in cases where sucrose is present by the adoption of a standard temperature say 17.5" C.At this temperature the iodine reduction of 10 grms. of sucrose for 10 minutes in presence of 40 C.C. of 0.05 N iodine solution and 5 C.C. of 0.5 N sodium hydroxide solution is 0.0032 grm. per 1 grm. of sucrose. The figures of Tables X. XI. and XII. are rather lower than this; but these were obtained at room temperature which although not taken at the time was certainly lower than 17.5" C. For practical purposes it will be a sufficiently close approximation to take the figure 0.003 for the iodine value of sucrose. The figure obviously only becomes of importance at all in analysis when the amount of sucrose is relatively large compared with those of the sugars which are completely oxidised. IV. LBVULOSE. Most observers have reported no oxidation of lzvulose by alkaline iodine, but Miss Judd and Baker and Hulton found values of 0-10 grm.of iodine per grm. of laevulose. If this figure is correct it will obviously seriously affect any attempts at estimation of dextrose in presence of lzvulose. Miss Judd gives no data as to the lzvulose used merely stating that its purity was tested by the polarimeter. The sample used by Baker and Hulton is described as having been recrystallised from alcohol having [alD= -88.4 and a reducing power with Fehling solution calculated as lzvulose of 99 per cent. Inasmuch as the [a]g of lzvulose at a concentration of 10 per cent. is -92-9" C. (Vosburgh) it appears doubtful whether their sample could have been entirely free from dextrose. For these experiments a sample of lzvulose purchased as pure and having [a]g-85-6" C .on dry basis in 20 per cent. solution was recrystallised by the method described by T. S. Harding (J. Amer. Chem. SOC. 1922 44 1755). The product from the second crystallisation had the following analysis :-Moisture, 0.4 per cent.; ash 0.02 per cent.; [a12 (20 per cent. solution) -94.1" C. (on dry basis). (Vosburgh's formula for this temperature and concentration requires -94.3" C.) (a) Efect of Varying Proportions of Alkali.-The lzvulose in these experi-ments was separately weighed out for each titration and dissolved in 50 C.C. of water. From the results of Table XV. it appears that an excess of alkali causes a considerably increased oxidation of l~vulose. This is to be expected in view of the readiness with which lzvulose is attacked by alkalis.A few experiments were also carried out in which a small amount of dextrose was used in addition t METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 13 the laevulose ; in this case 50 C.C. of 0.05 N iodine solution were used (see Table XVI.). From the amounts of iodine reduced were deducted the amounts required by the dextrose for the respective proportions of alkali used; the remainder was taken as being the iodine reduction of the lzevulose. As before excess of alkali caused an increase in the oxidation of the lzevulose. TABLE XV.-LBVULOSE. EFFECT OF VARYING PROPORTIONS OF ALKALI (1). Amount of laevulose in each case:-2 grms. Time of reaction:-10 minutes. Blank titration :-40.32 C.C. of 0.05 N thiosulphate solution.Back titration. NaOH Thiosulphate (0.5 N) (0.05 N) solution. solution. No. C.C. C.C. 1 4 38.27 2 5 37 080 3 8 36 *43 Iodine (0-05 N ) Iodine solution per 1 grm. reduced. of sugar. C.C. Grm. 2.05 0.0065 2 -52 0 *0070 3.89 0-0124 TABLE XV1.-LXVULOSE. EFFECT OF VARYING PROPORTIONS OF ALKALI (2). Amount of lzvulose in each case:-6 grms. 0.08 grm. of the commercially pure dextrose (Table I.) also present. Time:-10 minutes. Blank titration :-49.95 C.C. of 0.06 N thiosulphate solution. Back titration, (0.05 N) solution NaOH Thiosulphate (0.5 N ) solubon. No. C.C. C.C. 1 5 30.41 2 6-25 29-17 3 8 28.48 Iodine (0.05 N ) solution reduced. 19 -54 20.78 2 1 4 7 C.C. Less amount due to Iodine dextrose per 1 grm.(Table I.). of laevulose. C.C. Grm. 2 -55 0 *0032 3.61 0 *0046 4.41 0.0056 (71) Eeect of Tewz$eratz&re.-Before proceeding further with the experiments on lavulose the temperature effect was examined as this also might be con-siderable as with sucrose. Accordingly 1 grm. quantities of lzvulose were treated by the standard method at temperatures of from 14.5" to 25" C. the same procedure being adopted as for sucrose. The temperature effect was even greater than for sucrose the iodine value being trebled between these extremes (see Table XVII.). It was evidently necessary here also to fix a standard temperature and 17.5" C. was therefore used for the further experiments 14 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC TABLE XVI1.-LBVTJLOSE.EFFECT OF TEMPERATURE. Amount of laevulose in each case:-1 grm. Amount of alkali:-Fi C.C. of 0.5 N NaOH. Time:-10 minutes. Blank titration :-39-31 C . C . of 0.05 N thiosulphate solution. Back titration. Thiosulphate (0.05 N ) Temp. solution. No. O c. C.C. 1 14.5 38-23 2 17.5 37 -69 3 19 37-26 4 25 36.08 Iodine (0-05 N ) solution reduced. 1 -08 1 -72 2 *05 3.23 C.C. Iodine per 1 grm, of laevulose. Grm. 0-0068 0.0109 0-0130 0.0205 (c) Eflect of Vayying ProPortions of Lwvzdose to 1odirce.-As with sucrose the experiments designed to show the effect of increasing quantities of lzevulose in proportion to iodine showed a falling off in the iodine reduction as the amount of sugar was increased (Table XVIII,).(No. 4 of this series is included although the temperature was not noted as it was determined on a separate small quantity of lzvulose which had been specially recrystallised from the original material. Its polarisation on the dry basis agreed with that required by Vosburgh's formula. The temperature was probably rather on the low side.) This decrease is most marked for smaller amounts of sugar and there appears to be a tendency to approximate to a constant figure of about 0.0065. TABLE XVII1.-LBVULOSE. EFFECT OF VARYING PROPORTIONS OF LBVULOSE TO IODINE (1). Amount of alkali used:-5 C.C. of 0.5 N NaOH. Time:-10 minutes. Temp.:-l7.S0 C . (except in 4). Blank titration :-39-31 C.C. of 0-05 N thiosulphate solution. Back titration. Iodine Thiosulphate (0.05 N ) Iodine (0.05 N) solution per 1 grm.Laevulose. solution. reduced. of laevulose. No. Grms. C.C. C . C . Grm. 1 0-16 38.86 0.45 0.018 2 1.0 37 959 1 -72 0.0109 3 2.0 36.57 2.74 0.0087 4 2-58 37 -22 2.94 0 *0072 5 5-0 34.03 5.28 0.0067 (Blank 40.16) If dextrose is also present in amount sufficient to reduce an appreciable quantity of the iodine the oxidation of the Izevulose is diminished. Table XIX. shows the results found for various quantities of lzvulose when 046 grm. of dextrose was also present. Here again the falling off in reducing power becomes less marked as the amount of lEvulose increases and appears to tend to a constant value of about 0.004 METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 16 TABLE X1X.-LBVULOSE. EFFECT OF VARYING PROPORTIONS OF LBVULOSE TO IODINE (2).Amount of pure dextrose (Table V.) present in each case:-O*O6 grm. Amount of alkali used:-5 C.C. of 0.5 N NaOH. Time:-10 minutes. Temperature :-17.5" C. Blank titration :-38-68 C.C. of 0.05 N thiosulphate solution. Back titration. Thiosulphate (0.05 N) Lavulose. solution. No. Grms. C.C. 1 0 25 *40 2 0.25 24.97 3 0.5 24.77 4 2 23-63 5 3 23.07 Iodine (0.05 N) solution reduced. 13-28 13.71 13-91 15.05 15-61 C.C. Less amount due to dextrose. C.C. -0.43 0.63 1-77 2.33 Iodine per 1 grm. of laevulose. Grm. -0*0109 0.0080 0.0056 0 *0049 (a) Efect of Time of Reaction.-As with sucrose time appears to be an important factor in the extent to which lzvulose is oxidised.Two grms. quantities of lzvulose were allowed to react for 10 20 and 30 minutes under the standard procedure. The iodine reduction which stood at 0.0087 after 10 minutes had increased to 0-0154 in 30 minutes but with a steady falling off in rate tending to a maximum of perhaps 0.02 (Table XX.). TABLE XX.-LSVULOSE. EFFECT OF TIME OF REACTION. Amount of laevulose in each case:-2 grms. Amount of alkali used:-5 C.C. of 0.5 N NaOH. Temperature:-l7-5" C. Blank titration :-39.31 C.C. of 0-05 N thiosulphate solution. Back titration. Thiosulphate (0.05 N) Time. solution. No. Minutes. C.C. 1 10 36.57 2 20 35-37 3 30 34-45 Iodine (0.05 N ) Iodine reduced. per 1 grm. solution of laevulose. C.C. Grm. 2.74 0-0087 3-94 0*0125 4.86 0.0154 (e) Iodine Value of Lamdose.-Contrary to what is required in the case of sucrose the point of analytical interest in connection with lzvulose is its iodine value in small amounts approximately equal to the amounts of dextrose likely to be titrated since in analytical work this is by far the most frequent case.Sucrose on the other hand may occur in much greater quantity and its effect has therefore been investigated over a wide range. If the figures for laevulose in presence of dextrose (Table XIX.) be plotted as a curve it is found that the iodine value when the lzvulose is about 0.06 grm. is approximately 0.012. For solutions of invert sugar etc. where about 0.12 grm. of invert sugar would be titrated per 40 C.C. of 0.05 AT iodine solution the effect of the lzvulose on the iodine must be reckoned as 0.012 grm.of iodine pe 16 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC 1 grm. of laevulose. Baker and Hulton but it is not altogether negligible. errors amounting to nearly 1 per cent. in the dextrose if not taken into account. This is very much less than that noted by Miss Judd or by It is sufficient to cause V. INVERT SUGAR. It now became of interest to examine how far the results established for dextrose and laevulose could be used for the analysis of mixtures containing invert sugar or by suitable inversion procedure sucrose. As shown above the extent of oxidation of levulose is modified by the presence of dextrose and the only point of interest here is the behaviour when the amounts of the two sugars are approxi-mately equal.(a) Iodine Value of Lczvulose in Presence of an Equal Amount of Dextyose.-By applying the method of extrapolation to the results for fairly large quantities of laevulose in presence of 0.06 grm. of dextrose (Table XIX.) it has already been shown that the iodine value of the laevulose when 0.06 grm. of this is present would be approximately 0.012. The apparent iodine value of the total sugar therefore, = 0.711. would be 1.410 + 0.012 2 In order to test this figure a solution containing 0-2 per cent. each of the pure recrystallised dextrose (previously dried) and lzvulose was prepared and carefully measured out from a burette in a series of increasing quantities containing from 0.04 to 0.16 grm. of mixed sugars. These solutions were titrated by the standard procedure and the results obtained are given in Table XXI.TABLE XX1.-INVERT SUGAR. IODINE VALUE OF MIXTURES OF EQUAL QUANTITIES OF DEXTROSE AND LEVULOSE. Amount of alkali in each case:-5 C.C. of 0.5 N NaOH. Time:-10 minutes. Temp. :-17.5O C. Blank titration :-39-52 C.C. of 0.05 N thiosulphate solution. Back titration. Iodine Thiosulphate (0.05 N) (0.05 N ) solution Dextrose. Laevulose. solution. reduced. No. Grm. Grm. C.C. C.C. 1 0.0199 0.0199 35 *05 4-47 2 0.0350 0.0350 31.67 7 -85 3 0 *0500 0.0500 28.32 11 -20 4 0.0651 0.0651 24.98 14.54 5 0 -0800 0 -0800 21.73 17-79 Iodine per 1 grrn. of mixed sugars. Gl-m. 0.712 0.712 0.7 11 0,709 0.706 The iodine value found for the mixed sugars was 0.712 for the smaller amounts, with a slight decrease with increasing amounts of sugar down to 0.706 for 0-16 grm.of sugars. Apparently the higher figures are due to the increase in the oxidation of laevulose as the dextrose diminishes. The rather low value for No. 5 may be due to a considerable diminution in the lzvulose oxidation as the limit of excess of iodine is approached METHOD TO THE ANALYSTS OF SUGAR PRODUCTS 17 (b) Iodine Value of Invert %gar from Sucrose.-A solution was next prepared by dissolving 1.900 grms. of the pure sucrose before used in 150 C.C. of water, adding 30 C.C. of 0.5 N hydrochloric acid aad boiling for 1 minute. The solution was then quickly cooled almost neutralised with 0.5 N sodium hydroxide solution, and made up to 500 C.C. A series of quantities was measured from a burette as above and titrated.A series of iodine values was obtained which were all about 0.010 higher than the corresponding value found for mixed lamdose and dextrose. (Compare Table XXII. with XXI.) Apart from this the slight decrease from the lower to the higher amounts of sugar corresponds closely to that shown in Table XXI. and probably has the same explanation. The higher figures for this series suggested the possibility of the presence of substances of higher reducing power than the sugars which could only be derived from the method of inverting the sucrose. In order to test this point, a solution of 0.2 grm. each of dextrose and lzvulose was prepared and treated by the same method used for inverting the sucrose (boiling with acid for 1 minute etc.) The solution was made up to 200 c.c.and measured portions titrated as before. The series (Table XXIII.) showed a gradation corresponding well with those of the previous series and with indications of very slightly higher values than those of Table XXI. though not approaching those of Table XXII. (See Bolton and Revis Fatty Foods p. 316.) TABLE XXI1.-INVERT SUGAR. IODINE VALUE OF INVERT SUGAR PREPARED BY BOILING SUCROSE SOLUTION WITH DILUTE ACID. Standard procedure. Blank titration :-39-52 C.C. of 0.05 N thiosulphate solution. Back titration. Iodine Iodine Thiosulphate (0.05 N) per 1 grm. Invert (0.05 N) solution of invert sugar. Sugar. solution. reduced. NO. Grm. C.C. C.C. Grm. 1 0.0404 34.92 4-60 0.723 2 0.0699 31.57 7.95 0.722 3 0.1001 28.15 11 -37 0.721 4 0.1296 24-80 14-72 0-720 5 0.1600 21.46 18.06 0-716 TABLE XXII1.-INVERT SUGAR.IODINE VALUE OF MIXTURES OF EQUAL QUANTITIES OF DEXTROSE AND LBVULOSE (AFTER BOILING WITH DILUTE HC1). Standard procedure. Blank titration :-39.50 C.C. of 0.05 N thiosulphate solution. Back titration. Iodine Thiosulphate (0.05 N) Iodine Mixed (0.05 N) solution per 1 grm. sugar. solution. reduced. of sugars. No. Grm. C.C. C.C. Grm. 1 0 ~0402 34.98 4.52 0.714 2 0-0403 34.96 4.54 0.715 3 0.0397 35-03 4.47 0.715 4 0-0701 31.64 7-86 0-712 5 0.1002 28.26 11 -24 0-712 6 0.1302 24.92 14.58 0.711 7 0.1599 21 a68 17 -82 0.70 18 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC (c) Efect of Boiling Dilute Hydrochloric Acid on Invert Sugar Sol.utions.-A more drastic treatment was then followed by dissolving 0.0801 grm.each of dextrose (dried) and lzvulose in 150 C.C. of water adding 30 C.C. of 0.5 N hydrochloric acid and boiling for 45 minutes. The solution was cooled neutralised and the whole titrated by the standard procedure. The iodine consumption was 39-51 -21.11 =18-40 C.C. of 0.05 N solution. This gives 0.729 grm. of iodine per grm. of mixed sugars-a value considerably higher than those of Table XXI. In a final experiment to emphasise this effect of boiling with acids 0-76 grm. of sucrose was dissolved in 150 C.C. water 30 C.C. of 0.5 N hydrochloric acid added, and the solution boiled for 2 hours then cooled neutralised and made up to 200 C.C. Measured portions were titrated with the results shown in Table XXIV.These figures point to the presence of considerable quantities of substances other than the sugars in this solution the only alternative being the unlikely conversion of lawulose into dextrose. The latter possibility was disposed of by estimation of reducing sugar by copper reduction; this showed that only 94.8 per cent. of the original invert sugar remained. Hence it appears certain that the boiling of invert sugar solutions with dilute hydrochloric acid such as used for inversion of sucrose results in the destruction of the hexoses with formation of products which reduce alkaline iodine. Even boiling for so short a period as 1 minute is sufficient to produce an appreciable amount of these substances. TABLE XX1V.-INVERT SUGAR. APPARENT IODINE VALUE OF INVERT SUGAR BOILED WITH DILUTE ACID FOR 2 HOURS.Standard procedure. Blank titration :-38.52 C.C. of 0.05 3v thiosulphate solution. Back titration. Thiosulphate Invert (0.05 N ) sugar. solution. 1 0 00402 33-51 2 0.0795 28-72 3 0-1202 23-85 4 0-1603 19-13 No. Grms . C.C. Iodine (0.05 N ) solution reduced. 5.01 9-80 14.67 19.39 C.C. Iodine per 1 grm. of invert sugar. Grm. 0-791 0.782 0-774 0.763 (d) Conditions for Satisfactory Inversion of Sucrose Solutions.-In order to eliminate the destructive effect of the acid as much as possible an inversion at a much lower temperature was tried. Ten C.C. of approximately 7 N hydro-chloric acid were added to 80 C.C. of the sugar solution and the flask allowed to stand in an incubator at 36" C.for 4 hours. The flask was then cooled the solution almost neutralised with dilute sodium hydroxide solution and made up to 200 C.C. Measured portions gave the figures shown in Table XXV. which agree well with those of Table XXI. (Mixtures of dextrose and lzevulose. METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 19 TABLE XXV.-INVERT SUGAR. IODINE VALUE OF INVERT SUGAR PREPARED BY INVERSION AT 36" C. Standard procedure. Blank titration :-39.45 C.C. of 0.05 N thiosulphate solution. Back titration. Thiosulphate Invert (0.05 N) sugar. solution. No. Grms. C.C. 1 0.0400 34.97 2 0~1000 28.23 3 0.1599 21 -58 Iodine (0.05 N ) solution reduced. 4-48 11 -22 17 -87 C.C. Iodine per 1 grm. of invert sugar. Grm.0,711 0-712 0.709 Since a four hours' inversion would be unsuitable for many analytical purposes, an attempt was made to quicken the process by carrying out the inversion at 60" C. for 10 minutes. This gives practically the procedure used in the neutral polarisation process (Jackson and Gillis Bureau of Standards Scientific Paper, No. 375) except that sodium hydroxide is used for neutralisation of the acid, instead of ammonia. The results are recorded in Table XXVI. and are within experimental limits, in agreement with those of the dextrose and l a d o s e mixtures. The low value for No. 4 again points to the fact that the limit of excess of iodine is being ap-proached. Under these conditions of inversion then and using about 0.12 grm. of invert sugar per 40 C.C.of 0.05 N iodine solution the iodine value of invert sugar appears to be 0.710 a value which is in close agreement with that anticipated from a consideration of the behaviour of the individual sugars in other than equal proportions. TABLE XXV1.-INVERT SUGAR. IODINE VALUE OF INVERT SUGAR PREPARED BY INVERSION AT 60' C. Standard procedure. Blank titration :-38.53 C.C. of 0-05 N thiosulphate solution. Back titration. Iodine Iodine Thiosulphate (0-05 N ) per 1 grm. Invert (0-06 N ) solution invert sugar. solution. reduced. sugar. No. Grm. C.C. C.C. Grm. 1 0.0398 34.05 4-48 0.714 2 0.0802 29.52 9-01 0.713 3 0.1 198 25.12 13-41 0.710 4 0.1603 20.76 17 -77 0.704 VI. ESTIMATION OF SUCROSE BY THE IODIMETRIC PROCESS. It has now been satisfactorily established that the iodine reduction of invert sugar formed from sucrose under satisfactory condition is 0.710 grm.of iodine per grm. of sugar; and that the sucrose before inversion has a value of 0.003. Hence an increase in iodine reduction of 0-707~0.95 will be noted per grm. o 20 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC sucrose inverted. This gives a factor of 0.744 for calculating sucrose from the difference between " direct " and " invert " iodine reductions. In both titrations there should be present from 0.08 to 0.14 grm. of total iodine-reducing sugar, calculated as invert for each 40 C.C. of 0-05 N iodine solution added. VII. ESTIMATION OF INVERT SUGAR BY THE IODIMETRIC PROCESS. From the experiments detailed above as to the effect of acid treatment on invert sugar solutions it will be evident that an accurate estimation of invert sugar iodimetrically is a difficult problem.In commercial and technical products containing invert sugar there may be varying quantities of the decomposition products affecting the iodine titration and unless the manner of preparation of the invert sugar is known and a standard can be prepared under the same con-ditions (which is seldom the case) its estimation by this method may be by no means exact. Nevertheless in the course of much work in this laboratory in-volving the analysis of invert sugar sucrose mixtures jams etc. it has been found that the figures obtained under the standard conditions of the present report do give fairly satisfactory results for invert sugar.If any doubt is entertained as to the results being obtained for invert sugar in the routine examination of a particular class of product an occasional check by the copper reduction method will at once show up any errors (as in the case of the experiments above Table XXIV.) . VIII. THE USE OF WEAK ALKALIS I N PLACE OF SODIUM HYDROXIDE. With a view to the elimination of the slight effects of lzvulose and sucrose on the alkaline iodine solution some experiments were carried out with weaker alkalis in place of the sodium hydroxide. Sodium Bicarboutate.-Ten C.C. of a 0.8 per cent. solution of the pure recrystallised dextrose were taken diluted to about 50 c.c. and 40 C.C. of 0-05 N iodine solution added followed by 10 C.C. of M/2 sodium hydrogen carbonate solution.The mixture was kept at 27.5" C. for 1 hour and was then acidified and titrated. Only 10.41 C.C. of 0.05 N iodine solution had been consumed, corresponding to an iodine value for the dextrose of 0-826. Without further prolonging the time or raising the temperature to an inconvenient extent it is evident that the complete oxidation of the dextrose could only be attained by using excessive amounts of the alkali which for several reasons (e.g. effervescence upon neutralisation) might be objectionable. Sodium Carbonate.-Ten C.C. of a 0.8 per cent. solution of the dextrose were used and treated with 40 C.C. of iodine solution and 5 or 10 C.C. of 0.5 N (a) ( b METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 21 sodium carbonate solution for half-hour periods at 17.5" C.and 27.5" C. results are given below (Table XXVII.). The TABLE XXVI1.-USE OF SODIUM CARBONATE AS ALKALI. 0.08 grm. dextrose in each case. Standing for 8 hour. Blank titration. Thiosulphate (0.05 N) solution. No. C.C. 1 39-30 2 39.30 3 39.30 Amount of 0.5 N sodium carbonate. C.C. 5 10 10 Back titration. Thiosulphate (0.05 N ) Temp. solution. O c. C.C. 27 -5 26.73 27 -5 21-64 17.5 21.95 Iodine (0.05 N ) solution reduced. 12.57 17.66 17-35 C.C. Iodine per grm. of dextrose. Grm. 0.997 1-401 1 *376 These figures were sufficient to show that with suitable conditions a satis-factory result could probably be obtained for dextrose by the use of sodium carbonate. Before proceeding further however it was thought advisable to determine to what extent the action on laevulose would take place.Two grms. of lzvulose were dissolved 40 C.C. of 0.05 N iodine solution and 10 C.C. of 0.5 N sodium carbonate solution added and the mixture kept for 8 hour at 27-5" C. (corresponding to No. 2 of Table XXVII.); a blank was carried out at the same time. The difference between the back titrations amounted to 3.96 C.C. of 0.05 N thiosulphate solution, giving an iodine reduction of 0.013 grm. per 1 grm. of lzevulose. Hence it appears that for the conditions likely to give a satisfactory result for dextrose the iodine reduction of the lzevulose is just as marked whether sodium carbonate or sodium hydroxide be the alkali used. Cajori used sodium carbonate to the extent of about 1 per cent.in the mixture with room temperature of about 20" C. and obtained satisfactory results for dextrose. Such amounts of sodium carbonate, in view of the present experiments might be expected to have an appreciable action on the laevulose. In Cajori's experiments however the lzvulose used was insufficient to show any effect on the iodine reduction within the limits of experimental error. There thus appeared to be no advantage in the use of sodium carbonate, and the necessity for a higher temperature or longer time of reaction placed it at a considerable disadvantage as compared with sodium hydroxide. Accordingly the investigation of its effects was not carried further. Borax-A number of titrations were made with the use of dextrose (The 0-5 N In the following summary of the (c) and iodine as before in conjunction with 0.25 N borax solution.solution crystallised and had to be diluted.) iodine values obtained the amount of alkali is expressed as 0.5 N solution 22 HINTON AND MACARA THE APPLICATION OF THE IODIMETRIC TABLE XXVII1.-IODINE VALUES FOR DEXTROSE WlTH BORAX AS ALKALI. No. 1 2 3 4 5 6 7 8 9 10 Amount of borax (0.05 N ) solution. C.C. 5 5 5 5 10 4 6 7 10 6 Time. 10 mins. 2 hrs. # hr. 1 9 , 1 Y , 2 hrs. 2 9 , 2 ,, J > 20 mins. Temp. c. 17.5 17.5 27 -5 27 -5 27.5 27.5 27 -5 27 -5 27-5 50" C. Iodine value found. 0.475 1 *201 1 -225 1.349 1 -264 1 a365 1 -395 1.380 1 0350 1 *409 Here again a satisfactory result for dextrose can be obtained but only by using a fairly high temperature or a sufficient length of time.It was observed that the blank estimations (made side by side with each dextrose titration) were not in close agreement at 27.5" C. differences amounting to as much as 0.2 C.C. being found which was a much greater difference than any found at ordinary temperatures. This adds still further to the objections to the use of weak alkalis, such as borax which require an elevated temperature for the reaction. The only justification for its use would seem to be the smallness of the effect on lzvulose, 2 grms. of which after 1 hour at 27.5" C. with the use of 5 C.C. of 0.5 N borax solution showed an iodine value of only 0*0005. Mixed Borax and Sodium Hydroxide.-A mixed 0.5 N solution of borax and sodium hydroxide was prepared with 2 equivalents of borax to one of sodium hydroxide (i.e.60.3 grms. borax and 6.7 grms. of sodium hydroxide per litre). This solution was tested as in the case of the borax alone. (a) TABLE XX1X.-IODINE VALUE OF DEXTROSE WITH THE USE OF MIXED BORAX AND SODIUM HYDROXIDE. Amount of alkali (0.5 N ) solution. Time. No. C.C. Hours. 1 4 1 2 5 1 3 6 1 4 7 1 5 5 2 Iodine Temp. value O c. found. 27.5 1 0355 ¶ 1.380 1.378 ? 1 0369 J ? 1 0400 ?, The complete oxidation could no doubt be obtained with this mixture but there appears to be no advantage over the use of borax alone and the effect on lamdose would probably be more pronounced METHOD TO THE ANALYSIS OF SUGAR PRODUCTS 23 SUMMARY.(a) Certain discrepancies in the literature on the subject as to the reduction by sugars of iodine in alkaline solution have been explained. (b) The effects of proportions of iodine and of alkali used and of time and temperature in the cases of dextrose lactose sucrose and laevulose have been examined. (c) Dextrose and lactose are quantitatively oxidised to monobasic acids under suitable conditions. The action on sucrose and lzvulose is small and very subject to the conditions of experiment but under definite conditions these sugars exert a constant reducing power. A standard procedure has been outlined which consists in using about 50 C.C. of solution containing about 0.08 grm. of dextrose or its equivalent adding 40 C.C.of 0.05 N iodine solution and 5 C.C. of 0.5 N sodium hydroxide solution, and allowing the mixture to stand for 10 minutes at 17.5" C. then acidifying it with 5 C.C. of 2 N sulphuric acid and at once titrating the excess iodine with 0.05 N thiosulphate solution. (a) (e) The iodine values found under these conditions are: Dextrose . . . . 1.410 grms. iodine per 1 grm. sugar. Lactose hydrate . . 0.705 , 9 Y , 2, Sucrose . . 0.003 , 3 Y J Y Y 9 , Lzvulose (in large amount) . . . . 0.0065 , ) > J 9 > > 9 , of dextrose) . . 0.012 ,) 8s 9 ,) #, Lzvulose (in presence of equal amounts (f) Sucrose can be estimated by an iodine titration before and after inversion, with an accuracy of about 0.2 per cent. provided the inversion is carried out at a temperature not exceeding 60" C.Invert sugar can be estimated in many products in the absence of lactose (and maltose) by a single titration with iodine with sufficient accuracy for technical control purposes. Weaker alkalis such as sodium carbonate or borax when used in place of sodium hydroxide necessitate a much longer time of reaction or a higher temperature and are therefore less suitable for use than sodium hydroxide. The iodine value for sucrose is then 0.744. (g) The iodine value may be taken as 0.710. (h) (Note.-While the above work was being carried out two papers have been published by I. M. Kolthoff (Zeitsch. Untersuch. Nahr. Gelziissm. 1923 45 131, 141) on the iodimetric estimation of sugars. The conditions arrived at for the estimation of dextrose and lactose with the use of sodium hydroxide for rendering the liquid alkaline are very close to those found here.A few experiments on the reducing effect of sucrose and laevulose are described and so far as the results go they are approximately in accordance with those of this report. The suscep-tibility of the reducing effect of laevulose to time temperature etc. is however 24 HINTON AND MACARA APPLICATION OF IODIMETRIC METHOD ETG. not worked out; consequently the conditions to be used in applying the suggested correction for the presence of lzvulose in estimating the dextrose of invert sugar are inadequately defined.) This investigation was carried out in the laboratories of the British Association of Research for the Cocoa Chocolate Sugar Confectionery and Jam Trades. The larger portion of the experimental work was done by J. R. Heather. DISCUSSION. Mr. CHARLES M. CAINES enquired whether the authors’ method was applicable to the accurate estimation of small quantities of sugar in blood and similar biological material. He mentioned that at the meeting of the British Medical Association at Portsmouth he was demonstrating the method recommended by Dr. Maclean for the estimation of sugar in the blood in connection with the new insulin treatment. While listening to the author it had struck him that if the process were capable of accurately estimating minute quantities of sugar it might afford a useful modification of the Maclean method which at present depended on the reduction of alkaline copper iodine solution and involved a full six rninut es’ boiling. Mr. A. E. PARKES enquired whether the authors’ method could be applied to mixtures of sugars such as lactose invert sugar and cane sugar in condensed milk, and glucose syrup invert sugar and cane sugar in jams. After clarification with lead acetate was it possible to obtain a solution which could be treated by the iodine process for the estimation of sugars? Mr. C. L. HINTON in reply said the process was originally introduced by biochemists for the estimation of sugars in plants. He considered it might be equally useful for the estimation of sugar in physiological products provided that proteins and other bodies which reacted with iodine were first removed. As regards the question of its application to jams after clarification they had found no difficulty in using the process for ordinary jams or for invert sugars and lactose but glucose rather complicated matters. One could use the process in conjunction with polarisation but if lactose and glucose were both present, the estimation became more complicated and it was necessary to use fermentation met hods. As regards sucrose the accuracy was equal to that of the Fehling method, and the process was very much more rapid

ISSN:0003-2654    

DOI:10.1039/AN9244900002

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C.of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem.Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ...... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900025

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C.of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem.Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900030

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900032

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C.of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem.Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ...... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900033

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900034

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900036

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C.of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem.Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ...... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900037

出版商:RSC    

年代:1924

数据来源: RSC

摘要:

ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood.The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather. The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent.of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem. Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C.of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed. The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C.of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed.The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.ORGANIC ANALYSIS 325 Soluble d i d s ... ... ... Non-thmins . . . ... Tannin ... ... . . I I - 1--- Percent. I Per Cent. Per Cent. 2.76 4-77 25-7 1-89 3.63 13.5 0.86 1-15 12.2 Heartwood. The only part of the wood which 4as any possible value as a souroe of tannin is the heartwood; the chief available raw material would be the sawdust. The tannin imparts a dark purplish-brown colour to the outside of hides, but the leather produced might be satisfaotory as a heavy sole leather.The liquor which oolIects an steam-kilning the wood contains from 7 to 10 per cent. of tannin. W. P. S. Estimation of Thiophene. P. E. Spielmann and S. P. Schotz. (J. Soc. Chem.Id., 1919,38,188-189T.)-The authors have examined various met-hods whioh have been suggested for the estimation of thiophene in benzene, and recommend the following modifioations of the basic mercuric sulphate and acetate methods : Basic Mercu/l.ic Szi,&hate Method.-Two C.C. of the benzene and 20 C.C. basic mercuric sulphate solution (sulphuric acid 20 c.c., water 100 ox., and mercuric oxide 5 grms.) axe shaken in a closed tube for three hours; the white precipitate which is formed is collected, washed with hot water, dried at 110" C., and weighed.The weight multiplied by 0.0757 gives the amount of thiophene in 2 C.C. of benzene. Basic Mercuric Acetate Method.---Ten O.C. of the benzene and 4 grms. of baaic mercuric aaetafe (mercuric oxide, 1 part, glacial aceti0 said, 2 parts, the mixture b~iing filtered and the salt washed with ether) are heated on a water-bath under a, reflux condenser for fifteen minutes ; after cooling, the precipitate i8 collected, washed with water, dried at 100" C., and weighed. The weight is multiplied by 0.07516 to obtain the oorresponding amount of thiophene. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9244900041

出版商:RSC    

年代:1924

数据来源: RSC