摘要:

994 SEYLER AND LLOYD: LXXXV.-Studies of the Carbonates. Part 111. Lithium Calciuni and iMacgnesiurn Carbonates. By CLARENCE ARTHUR SEYLER and PERCY VIVIAN LLOYD. I; it h iu m G’nr 71 o ti n t e . AIR was drawn through an N/10-solution of lithium hydrogen carbonate a t 25O. The percentage of carbonic acid in the air was determined as in the previous paper (this vol. p. 138)’ by draw-ing air through an N/lO-solution of sodium carbonate. c = 100.5 x 10-3 gram-equivalents per litre [H,CO,] = 0.0105 x 1OOz = hydrogen carbonate 40.65 per cent,. 100( 1 - x) =carbonate 59.35 per cent. This result is identical within the limits of experimental error with that for sodium carbonate a t the same concentration and 10-3. gives k2 k= 53%. k a2 Air was drawn through water containing lithium carbonate in 1OOz =hydrogen carbonate 23.4 per cent.lOO(1- x) = carbonate 76.6 per cent. This result agrees with McCoy’s value for sodium carbonate at Lithium carbonate when shaken with water alone (c = 338 x It is evident, therefore that the ionisation of lithium carbonate and hydrogen carbonate can bO taken as equal to that of sodium carbonate and hydrogen carbonate. A series of experiments was made the results of which although only preliminary are worth recording. Lithium carbonate was shaken with water containing increasing amounts of carbonic acid in bottles without air space until equilibrium was presumed to be reached. The proportion of carbonate and hydrogen carbonate to total base was ascertained by double titration without special pre-cautions except against loss of carbonic acid.The solid phase, even when the solution contained chiefly hydrogen carbonate, appeared to be lithium carbonate as determined by dissolving a portion in pure water and titrating as above. The concentration of the free carbonic acid was not determined but can be approxim-excess. c = 363 x 10-3 equivalents. }t 5 = 4272. the same concentration. behaved analytically like a pure carbonate. ately calculated by the equation [H2C03]=-s k .-j CHC%I2 and is k IC% STUDIES O F THE CARBONATES. PART 111. 995 small in any case. The object was to ascertain whether the solu-bility product [Li]2 x [CO,] was approximately constant. Such experiments would afford a criterion as t o whether the intermediate ion LiCO really exists since i f it does the lithium ion concentra-tion will be [HCO,] + [LiCO,1 + Z[CO,] whilst if it does not it will be [HCO,] + Z[CO,].If b is the molecular concentration of the total hydrogen carbonate and c that of the carbonate as determined by analysis, we should have in the first case [Li]=a(b + c ) + p c and in the second [Li’] = ah + 2 P c ; j3 is taken to be the same as for sodium carbonate a t the same total lithium concentration and a to be the same as for sodium acetate at the same molecular concentration, that is a t the concentration b - t c . The non-ioiiised [Li,CO,] will be (I -a)b and the [LiCO,]==c(a-P). Equivalent concentrat ion. b+ 2c. b+c. b. 338 x 10-3 109 x 10-3 0 363 224 85 364 215 66 386 248 110 406 282 158 706 635 570 818 773 728 a.0-75 0.72 0.72 0.71 0.70 0.595 0.56 CHCO3I. C. o x 10-3 169 x 10-3 61.2 139 47.5 149 78.1 138 110.6 124 339.0 65 407.7 45 8. 0.295 0.285 0.285 0-275 0.267 0.187 0.165 W,l. [Li.] [Li’]. [Li] x z[CO,]. [Li’] x 2[C0,]. 49.85 x 10-3 176.5 x 99.7 x lo-” 1-553 x 0.495 x 39.60 200.9 140.4 1.598 0.780 42-50 197.3 132.5 1-654 0.740 37.9 214.0 153.9 1.736 0-89 33.2 230.6 177.0 1.765 1.04 12.1 389.9 363.2 1-84 1-69 7.42 441.2 422.5 1.46 1.32 On the assumption of an intermediate ion the value of [Li] x [CO,] is fairly constant whereas on the other assumption there is no constancy until the effect of the intermediate ion becomes negligible. I t will be found that although [LiI2 x [CO,] is approximately constant the non-ionised [Li,CO,] diminishes so that [Li12 f c r ) 2 1 = kakb increases.Since [LiI [“3] =kb is [Li VV ] Li CO,] roughly constant* (see this vol. p. 143) it follows that the p r e duct [Li] x [LiCO,] must also be approximately constant. It seems therefore that i t is the non-ionised molecule that does not follow the law of mass action o r of which the concentration is not a true measure of the active mass. These experiments indicate a line of research which is worth pursuing by experiments in which all the conditions art3 accurately controlled. * kb increases with the concentration but much less rapidly than k,. Q Q VOL. CXI 996 SEYLER AMD LLOYD: Calcium Carbonate. Stieglitz (Carnegie Institution Pub. 1909 No. 107) and McCoy and Smit,h ( J .Anter. C'kem. Soc. 1911 33 468) have calculated the solubilit,y product [Ca] x [CO,] = li of calcium carbonate from the value of 2$[Ca] x [CO,] obtained by Schloesing (or by McCoy 7% and Smith). Stieglitz used the value k3=6*2 x 10-11 and McCoy and Smith 5.5 x 10-11. It has been shown (Part II. Zoc. cit.) that these values are prob-ably too high. = 7124 and 5 = 19-2 x 10-5. Consequenbly the value of [Ca] x [CO,]= k, obtained by Stieglitz and by McCoy and Smith is too high. Taking the result of McCoy and Smith's experiments we have 2 4 = 102.5 x 10-6 whence [Ca] x [CO,] = X = 71.9 x 10-lo a t 2 5 O . We found the values 1;,=4*27 x ki3 k, k k, McCoy and Smith calculated i t t o be 93 x 10-10 and Stieglitz 126 x 10-10. This high result explains why the calculations of the solubility of calcium carbonate in pure water have hitherto been materially larger than the value found by experiment.gram-molecules per litre at 2 5 O whilst Kendall (Phil. Mag. 1912, [vi] 23 958) found only 14-33 x 10-5. We recalculate it on a basis of [Ca] x [C03]=71*9 x 10-10 as follows The pure calcium carbonate is largely hydrolysed a t this dilution thus : where the concentration [HCO,] = [OH]. McCoy and Smith for instance calculated it to be 16.6 x CaCO + 2H,O = Ca(O13)2 + Ca(HC0,)2, Therefore [Gal = [CO,] + R CHCO 1 + - [OH] - [CO,] + [HCO,]. 2 2 Also If 1 0 0 ~ is the percentage of the calcium carbonate hydrolysed, [HCO,] = z[Ca], [CO,] = (1 - x)[ca], But [Ca] x [C03]=[Ca]2(1-x)=71.9 x 10-lO STUDIES OF THE CARBONATES.PART 111. 997 We have two equations for [Ca] and x which are satisfied by [Ca]= 14.6 x 10-5 and x=O.666; that is to say the solubility of calcium carbonate will be 14.6 x 10-5 gram-molecules per litre of which two-thirds will be hydrolysed. The alteration of to 1-67 x 10-4 will make very little change. [Ca] will become 14.24 x 10-5 and x=0*645. The solubility of calcium carbonate using normal air can also be calculatced : [HC0q]2 LCOsI * L'%CO,I Therefore, k3 = 7124 [Ca] x [CO,] =71.9 x 10-10 [HUO,] = 2 ([Cat] - EC03I ) * ([Ca] - [CO,] i 2 - '7124 - - -[ H,COs]. [CO,I 4 F o r air containing 0.037 per cent. of carblon dioxide [H,CO,] a t 2 5 O will be 1-221 x 10-5. This will give [a]=54.7 x 10-5 but Ken-dall fouad considerably less.I n an experimegt conducted a t about 15O it was found t h a t after twenty-eight days the solubility of powdered limestone suspended in water through which air from outside the laboratory was drawn was 33.7 x 10-5. After sixty-nine days it rose t o 54.2 x 10-5 and after two hundred and forty days to 57.5 x 101-5 so that equilibrium is only slo cvly relach ed. Assuming 0.033 per cent. of carbon dioxide in the air [H,CO,] a t 15O = 1.475 x 10-5. This will give [a] = 58.2 x 10-5 against 57.5 x 10-5 fo'und. F o r air containing 0.0333 per cent. of carbon dioxide Schloesing found (at 18.) 54.88 x 10-3. The solution of the carbonate in equilibrium with air was found t o have a slightly alkaline reaction to phenolphthalein. (For a full discussion of the subject see Johnston and Williamson J .Anzer. Chem. Soc. 1916 38 075.) His result appears to be low. Magnesium Cnrb oilate. Bodlander has calculated the ratio from Engel's experiments on the solubility of crystallised magnesium carbonate MgCO,,SH,O in water containing carbonic acid under pressures of from 4 to 6 atmospheres. A t these tensions the carbonate is a stable solid phase. The difficulty presents itself t h a t the carbonate unlike calcium barium or strontium carbon 998 SEYLER AND LLOYD: ates is not sparingly soluble. Engel states t h a t it is soluble in pure water t o the extent of 11.5 x 10-3 gram-molecules per litre a t 12.5O, and Bodlander assunies t h a t 56 per cent. is dissociated giving a concentration of 5.06 x 10-3 for the non-ionised part which Bod-lander dedncts in calculating the concentration of the magnesium and hydrogen carbonate.However this is erroneous. Crystallised magnesium carbonate has no definite solubility in pure water. It is decomposed into basic compounds and the solution contains magnesium hydrogen carbonate with a certain amount of ionised and non-ionised carbonate. The magnesium in solution depends on the ratio of water to solid employed and the equilibrium takes some time to reach completion. The following results bearing on this question were obtained. The total carbonic acid was determined by Dittmar's ' vacuum method ' (" Quantitative Chemical Analysis," p. 227) used by him for sea-water the ' fixed ' carbonic acid by titration with methyl-orange as indicator : [COZl Time Water C 3 .CWHCO:~)~. [MgOI' (days) - P a x * 2 2 cI1IgCO.p in solid C%CO& 440 unknown 5.98 x 10-3 1.58 x 10-3 2.20 x 10-3 0.775 440 370 8.48 3.48 2.50 0.772 - 15.96 10.21 2.87 - 0.0103 x lo-' 335 unknown 31.0 22.15 4.57 0.79 47 17 47.5 34.1 6.70 0.84 338 unknown 48.9 33.9 7.50 -47 8.5 60.0 46.6 6.70 0.79 47 2.0 76.62 63.5 6.56 0.79 The subject deserves careful investigation but i t is evident t h a t the carhonate below a certain tension of carbonic acid is decom-posed until the solid phase is not far removed from hydromag-nesite 3MgC03,B!Ig(OH),,3H,0 ( ratio ~ ~ ~ ~ ~ ~ 1 - 0 * 7 5 ' ) - which is, stable over a fairly wide range of concentration of carbonic acid. The magnesium remains in solution largely as hydrogen carbonate, with a proportion of carbonate both ionise'd and non-ionised.The main rextion is approximately 5MgC03 + 2H20 = 3MgC03,Mg(OH) + BTg(HCO,),. Consequently the greater thel amount of magnesium carbonate in relation to t h s water the greater is the concentration of the solu-tion. The dissolved carbonate with increasing concentration (and when sufficient time is allowed) becomes nearly constant a t a value about 7.5 x 10-3 gram-molecules per litre. This is probably almost entirely non-ionised. The following experiments show t h a t mag-nwium c a r h n a t e is ,only slightly ionised even a t high dilutions. Air wm drawn through water containing magnesium carbonat STUDIES O F THE CARBONATES. PART 111. 999 in suspension a t 2 5 O . The percentage of carbonic acid in the air was determined by drawing it through an N/lO-solution of sodium carbonate and determining the proportion of hydrogen carbonate and carbonate.Total magnesium in solation = 15.96 x 10-3 gram-equivalents per litre. Hydrogen carbonate = 63.97 per cent. ; carbonate = 36.03 per cent. Concentration of free carbonic acid = 0*0103 x 10-3 : A similar experinleiit was made with a solution of about the same concentration b u t no solid was present. Total magnesium in solution z 18.65 x 10-3 gram-equivalents. Hydrogen carbonate = 60.48 per cent. ; carbonate = 39.52 per cent. : The mean value of It is 3566 for 2 concentration of 17.3 x 10-3 equivalents. Taking the ionisation of the magnesium hydrogen carbonate as equal t o that of magnesium nitrate say 0.84 we cal-culate 6 as follows: 3566 7124 p = - a2 = 0.353.Evidently even a t an equivalent concentration of 17.3 x 10-3 magnesium carbonate is only slightly ionised. From the above experiments we calculate the relation : It would be possible by careful experiments to determine 6 f o r higher concentrations but i t is evident t h a t a t such concentrations as obtained in Engel's experiments the magnesium carbonate will be practically non-ionised. Some experiments of Treadwell and Reuter (Zeitsch. nnorg. Chem. 1898 17 ZOO) are unfortunately not available for calculating fl since the solutions are not in true equilibrium with the gaseous phase but they show t h a t beyond concentrations of magnesium of 50 x 10-3 equivalenh the amount of carbonate is practically constant.The maximum value is 9.0 x 10-3 gram-molecules per litre. We will take this as the con-centration of the non-ionised carbonate in Engel's experiments. These wsre carried out a t 12.5O. The concentration of the free carboniz acid has to be calculated from the pressure which is not strictly correct for carbonic acid 1000 STUDIES OF THE CARBONATES. PART 111. Pressure. Atmo-spheres. 0.5 1.0 1.5 2.0 2.5 3.0 4.0 6.0 CMg-9). a. 245 x 0.686 316 0.680 374 0.675 407 0.672 435 0.670 456 0.669 509 0.666 603 0.662 %k,. 168.1 x 336.2 x 10-3 21.55 x 88.17 219.8 429.6 41.80 94.80 252-4 504.8 60.9 105.6 273.5 547.0 79.8 102.5 29 1-5 583.0 99.75 99.3 305-0 610.0 116.4 97.5 339.0 678.0 151.6 102.8 227.2 117.2 399.2 798.4 Wgl.CHCO,I. [H,CO,I. k, Mean ............... 100.57 The concentration of the CO ion is calculated from the relation : [CO 3 = ______-- [HC0,I2 a [H,CO,] x 7120’ From these figures we may calculate the value of the (‘solubility These estimates of the (‘ solubility product ” must be subject to product,” [Mg] x [CO,] namely 141.2 x k correction for the value of -2 which is strictly only known f o r 2 5 O . 4 co IT clzc s io 71 s . (1) Lithium carbonate is ionised tcj the same extent as sodium carbonate. The ionisation takes place in two stages Li,C03 = Li + LiCO and LiCO,=Li + CO,. Consequently the concentration of the lithium ion is more than double t h a t of the CO ion and can be calculated. If this is done it is found t h a t the “solubility product,” [LiI2 x [CO,] is practically constant over a wide range, thus confirming the assumption made.(2) The solubility product of calcium carbonate [Ca] x [CO,] is about 71.9 x 19-10 and has hitherto been put a t too high a value. It is shown that- this agrees with a 2olubility of calcium carbonate in pure water of [Ca]= 14.6 x 10-5 and t h a t the salt is hydrolysed to the extent of 66 per cent. (3) Crystallised magnesium carbonate has no definite solubility in pure water. It decomposes into basic carbonates and magnesium hydrogen carbonate whilst a certain amount of carbonate is also dissolved. Over a wide range the reaction approximates t o 5MgC0 + 2H,O = 3MgCO,,Mg(OH) + hlg(HCO,),. The larger the amount of carbonate in relation to the water the larger is the amount of dissolved hydrogen carbonat’e but the carbonate tends t o reach a limit. (4) It is shown t h a t a t an equivalent concentration of 17.3 x 10-3 magnesium carbonate is only ionised (as regards the CO ion) to th INTERNATIONAL ATOMIC WEIGHTS. 1001 extent of about 35 per cent. and probably a t high concentrations it is only very slightly ionised. The " solubility product " of magnesium carbonate a t concentra-tions of free carbonic acid a t which the carbonate' is a stable solid phase has been calculated from Engel's experiments and is found to have the1 value 141 x 10-6. [Received August 25th 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171100994

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

INTERNATIONAL ATOMIC WEIGHTS. 1001 International Atomic Weights. THE Council has ordered the follo,wing letter and Table t o be printed in the Journal of the Society: WHINFIELD, SALCOMBE, S. DEVON. October l s t 1917. DEAR SIRS, I beg to inform you that the International Atomic Weight Committee have decided t o intermit their Annual Reports owing primarily to the fact that certain of its members a10 largely occupied with matters arising out of the War and that it has been found difficult owing to the interruption of communications to keep in correspondence. Furthermore-and this is the more important circumstance-practically all experimental work on the subject of Atomic Weights is for the time being interrupted; indeed with the entrance of the United States of America into the War i t may be said to be for the present wholly a t an end, and no memoir of importance has made its appearance since the issue of the last Report.As no change has been shown to be required in the Table last published it is suggested that it should be reprinted as i t stands and regarded as current for 1918. I am GENTLEMEN, Your obedient Servant, T. E. THORPE. The Hon. Secretaries, The Chemical Society, Burlington House, London W 1002 ~ INTERNATIONAL ATOMIC WEIGHTS. Oxygen ........................ o Palladium ..................... Pd Phosphorus .................. P Platinum ..................... Pt Potassium ..................... 11 Praseodymium ............... Pr Radium ........................ Ra Rhodium .....................Rh Rubidium ..................... Rb Ruthenium .................. Ru Samarium .................... Sa Scandium ..................... Sc Selenium ..................... Se Silicon ........................ Si Sodium ........................ Na Strontium .................. Sr Sulphur ..................... S Tantalum .................. Ta Tellurium ..................... Te Terbium ..................... Tb Thallium .................... T1 Thorium ..................... Th Thulium ..................... Tm Tin ........................... Sn Titanium ..................... Ti Tungsten ..................... W Uranium ..................... U Vanadium .................. V Xenon ........................ Xe Ytterbium (Neoytterbium) Yb Yttrium .....................Yt Zinc ........................... Zn Zirconium ..................... Zr ........................ Silver Ag 1918 . Znt ernatio nal A tomic IV eigh ts . Symbol . Aluminium ................. A1 Antimony ..................... Sb Argon ....................... A Arsenic ..................... As Barium ........................ Ba Bismuth ..................... Bi Boron ........................ E Bromine ..................... Br Cadmium ..................... Cd Caesium ....................... Cs Calcium ..................... Ca Carbon ........................ C Cerium ........................ Ce Chlorine ..................... C1 Chromium .................. Cr C'obal t ....................... Co Columbium .................Cb Copper ........................ Cu Erbium ..................... Er Europium ..................... Eu Fluorine ..................... F Gadolinium .................. Gd Gallium .................... Ga Germanium .................. Ge Glucinum ..................... G1 Gold ........................... Au Helium ........................ He Holmium ..................... Ho Hydrogen ..................... H Indium ....................... In Iodine ........................ I Iridium ......................... Ir Iron ........................... Fe Krypton ..................... Kr Lanthanum .................. La Lead .......................... Pb Lithium ..................... Li Lutecium ................... Lu Mangaaneae .................. Mn ................. Dysprosium DY .................. Magnesium Mg Mercury Hg ..................... Atomic weight . 27 *1 120.2 39-88 74*96 137'37 208'0 11.0 79.92 112'40 132.81 40.07 12.005 140'25 35.46 52.0 58.97 93'1 63.57 162.5 167-7 152.0 19.0 157.3 69.9 72.5 9'1 197.2 4-00 163'5 1 '008 114.8 126.92 193.1 55-*84 82.92 139-0 207'20 6 '94 175.0 24-32 54'93 200'6 Atomic weight . 96. 0 144 *3 20.2 58.68 262.4 14-01 190 -9 16'00 106.7 31.04 195.2 39'10 140.9 226 *O 102 '9 101-7 150-4 44'1 79.2 28.3 107'88 23'00 87-63 32.06 85.46 181.5 127.5 159.2 204.0 232'4 168.5 118'7 48-1 184-0 238'2 51'0 1 * 2 SD 173'5 88.7 65*37 90-

ISSN:0368-1645    

DOI:10.1039/CT9171101001

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

TEMPERATURE OB IGNITION OF QASEOUS MIXTURES. 1003 T~XXXVI.--The Temperature of Ignition o j Gaseous Mixtures. By JAMES WALLACE MCDAVID. NUMEROUS methods for the determination of the ignition-tempra-ture of gaseous mixtures are t o be found in the literature and these have already been classed into three groups by Dixon and Coward (T. 1909 95 514) in their paper on this subject. The experimental conditions governing this division are as follows : I. A bulb containing the gaseous mixture was plunged into a bath which was maintained a t a constant temperature. 11. A mixture of the gases was passed through a tube in a bath which was gradually being heated. 111. The gaseous mixture was compressed adiabatically and from the pressure required to ignite it the temperature of the mix-ture a t the ignition-point was calculated.I n each of the above methods the gaseous mixture is retained in the state necessary f o r ignition for some considerable time and i t is quite possible therefore that before the ignition-temperature is reached a state of slow combustion ensues which generates sufficient heat t o raise the remainder of the gaseous mixture to its ignit ion-point With regard to the third method which was that used by Falk ( J . Amer. Chem. SOG. 1906 28 1517; 1907 29 1536) Dixon and Coward point out t h a t the temperature of ignition of a gaseous mixture under abnormal pressure may be totally different from that of the same mixture under normal pressure. I n the method adopted by Dixon and Coward the two gases were allowed t o flow through two concentric tubes which were heated in an electric furnace and allowed to mix a t the top of the shorter (inner) tube.A thermo-couple was placed near to the nozzle of the inner tube. I n these experiments in addition to the time factor the fact that the gases are flowing must also be taken into consideration and thO results obtained by these authors show that the rate of flow and the size of the nozzle of the inner tube affect the results; for example when the rate of flow of hydrogen was very dow namely 2.4 C.C. per minute and the rate of flow of oxygen was 50 C.C. per minute the temperature of ignition was 7 9 2 O whilst when the rate of flow of hydrogen was 19 C.C. per minute oxygen still flowing a t 50 C.C. per minute, the ignition-temperature waa found t o be 599O.These authors, VOL. CXT. R 1004 McDAVID THE TEMPERATURES OP however give in their paper a definition as t o what they have taken as the temperature of ignition It seems that' it is advisable to eliminate as far as possible the time factor in determining the ignition-temperature and it' is also preferable to have a stationary tolume of gas. In table I the results obtained by -various workers for several gaseous mixtures are given. TABLE I. I9 12.i t io 11- t e ) ) I p e m t ii I * es of 1) iff e re I I t G'cc .s e o 11 s Mi L t u r e s . Temperature of ignition Hydrogen and Meyer Hrause L4?aizale?~ 1891 264 85 ; 518-606" Gases. 0 bserl-er. Reference. found . Oxygen. Askenasy . ibicl. 1892,269 49 2421 Zeitsch.physikal. Chein., 1893 11 25. , , Rodenstein. Ibid. 1899 29 665. 653-710 , , Meyer and Freyer Ber. 1892 52 662 700 ) , GautierandHBlier G'ompt. rend. 1896 122 840 y y Helier Ann. chi^. Phys. 1897 845 y , Palk J . Ainer. Chem. Soc. 1906 514-540 556 [vii] 10 521. 28 1517; 1907 29, 1536. y 7 , DixoiiaiidCoward T. 1909 95 514 580-590 Rletliaiio and Illeyer and Freyer Zeitsch. physiknl. C17~on. 606-650 Oxygen. 1893,11 28. , , Meyer and Murich Ber. 1893 26 2421 656-678 , , Dixoii aiid Coward Zoc. cit. 5 5 6-7 00 Ethylene a.nd Meyer and Freyer ,) , , illeyer and Munch ,, , , DixonandCoward ,, Carbon mon- Meyer and Freyer ,, , , Bleyer and Munch ,, , , DixonttndCoward ,, Oxygen. oxide and oxygen 530-606 577-590 500-519 650-730 Combined quietly 637 658 The methods now described eliminate so far as is practically possible the time factor.The temperature of ignition in these experiments is taken t o be that temperature t o which the gaseous mixture must be heated by the npplicatioi? of a hot body so as to cause instantaneous ignition. The temperature of ignition 11x3 in the present woik only been determined for various gases when mixed with air. Dixon anti Coward have however showii t h a t there is very little difference in the temperature found when air or oxygen respectively is employed IGNITION OF GASEOUS MIXTURES. 1006 The first set of experiments deecribed below was originally undertaken with a view to obtain comparative values €or the temperatures of ignition of various gases but the results seemed of sufficient value to warrant further work being carried out.As a consequence numerous variations and improvements were intro-duced and finally a method was devised which was simple rapid, and capable of giving accurate iesults Details of all the variations of the method have however been included as several of them appear t o be useful for comparative purposes a t least although n o t sufficiently accurate for the deter-mination of absolute values. The results obtained by the method linally adopted for the ignition-temperatures of the various gases tested are given below: Coal gas air ....................................... 878" Ethylene-air ....................................... 1000 Hydrogen-air ....................................747 Carbon monoxide-air ........................... 931 Petrol (fraction O-SO")-air .................. 995 13enzene -air ....................................... 1062 Ether-~ir .......................................... 1033 E x P E R I M B N T A L. The essence of the method employed in the following experi-ments consists in the ignition of a small volume of the gaseous mixture contained in a soap bubble by means of an electrically heated wire or other red-hot body the temperature at which ignition just takes place being noted. A quantity of the gas to' be experimented on was mixed with air and made up t o the required concentration in a IO-litre gas holder. To the outlet' tube of the holder was attached a piece of capillary tubing terminating in a bulb tube shaped like the head of an ordinary tobacco pipe.This tube when not in use dipped into a solution of sodium oleate and glycerol in water. The apparatus employed for igniting the gas consisted of a platinum wire measuring about 0.025 cm. in diameter which was wound evenly round a small thin-walled silica tube. A thermo-couple made of platinum-rhodium which had previously been care-fully standardised against' a standard pyrometer was passed through the inside of the silica tube so that the thermo-junction was in the centre of the tube. The terminals of the thermo-couple were connected to a millivoltmeter from which the temperature could be read off. The experiments were carried out in a darkened roo~xi as in some cases the flame of the ignited gas was almost' invisible in daylight.The procedure was as follows When a11 the connexions had been made the heating current' which could be varied by means R R 1006 McDAVID THE TEMPERATURES OF of a rheostat was switched on. When the temperature as indicated by the millivoltmeter was constant the tap of the gas holder was opened and the mixture flowing through the pipe stem and soap solution produced a bubble. The t3ap was closed and the bubble still on the end of the pipe was placed in contact with the hot coil. Ignition was instantaneous and was usually accompanied by a slight explosion but in some cases t'his was so faint as to be detected only with difficulty. The temperature was varied over 60-80° until a sufficient number of readings had been obtained.The gases employed in the first instance were prepared as follows : Hydrogen.-From pure zinc and sulpiiuric acid. Methane.-By the action of a zinc-copper couple on methyl iodide. The gas was passed through a tube containing more of the zinc-copper couple in order t o free it from methyl iodide vapour. Et hyZene.-By passing alcohol vapour over heated aluminium oxide. The gas obtained contained 9 per cent. of methane. Coal Gas.-Samples were taken from time t o time from the local gas supply. Petrol.-Commercial petrol was fractionated and 2 C.C. of the fraction boiling between Oo and 80° were vaporised and made up t o 10 litres with air. Benzene and Et her.-Pure chemicals were used and vaporised as in the case of petrol. The results found are given in the following tables.TABLE 11. Coinprison of Coal Gas-Air and ,Wethane-Air Mixtures : 90.5 per cent. of Air in Mixture. Rotherham gas. Ardeer coal gas Methane. ,- \ 7'- I-ature. Result. ature. Result. ature. Result. Temper- Temper- Temper-760" No ignition 760" No ignition 840' No ignition 7 60 9 9 780 Ignition 860 9 9 765 9 9 780 No ignition 865 11 7 80 9 9 7 80 9 9 870 Y Y 7 90 9 9 7 90 Y Y 880 Y Y 790 Y Y 7 90 9 9 880 9 9 795 9 7 795 Ignition 880 1 9 800 Ignition 795 Y 9 880 9 9 805 9 9 800 No ignition 880 Y9 806 9 ) 800 Ignition 880 Ignition 810 Y9 800 9 9 880 9 > 810 9 Y 800 Y 9 8 80 Y 9 830 Y Y 810 9 9 890 9 ) 840 9 9 820 9 9 920 9 9 Temp. of ignition = 800'. Temp. of ignition= 800'. Temp. of ignition= 880' IGNITION OF GASEOUS MIXTURES.1007 TABLE 111. Comparison of Coal Gas Methane and Hydrogen-Air iNiztures : 86.5 per cent. of Air Present. Rotherham coal Tem- Tem- Tem- Tem-per- per - per - per -ature. Result. ature. Rosult. ature. Result. ature. Result. 780" No ignition 800" No ignition 6'70" No ignition 860' KO ignition gas. Ardeer coal gas. Hydrogen. Methane. /- I- -785 9 9 800 9 9 6 80 9 9 870 9 9 7 86 9 9 805 9 9 080 9 9 876 9 9 800 9 9 805 Ignition 690 9 9 880 No ignition 800 Ignition 810 No ignition 690 9 885 Ignition 800 9 9 810 ? ? 690 Ignition 885 ,, 805 Noignition 810 9 9 690 9 9 890 ? 9 815 , 700 9 9 710 9 9 720 ,) 9 9 9 9 805 690 875 Ignition 800 815 Ignition 810 Ignition 700 Noignition 900 ,, 815 9 9 810 , 700 Ignition 910 ,, 820 . 710 NO ignition 820 9 3 710 Ignition - -I__-Temp.of ignition Temp. of ignition Temp. of ignition Temp. of ignition = 806". = 810". = G95". = 885". TABLE IV. Cornprison of Petrol and Ethylene-Air Mixtures. Mixture of 9.1% C,H, O.9q0 CH,, and goo/ air. Tompsr- No. of ature. readings. Result. 845" 1 Ignition 840 2 9 ) 830 7 9 9 825 8 9 9 825 1 No ignition 820 4 Ignition 820 12 $0 ignition 815 3 9 9 s10 3 9 9 Temp. of ignition = 825". Mixture of 2.0 C.C. petrol (&SOo) vaporised and made up with air t o 10 litres. * r \ Temper- No. of ature. readings. Result. 900" 3 Ignition 890 3 9 9 8 80 6 9 , 8 80 7 No ignition 875 2 Ignition 875 5 No ignitioli 870 5 Y 9 865 2 9 9 Temp. of ignition = 885". A second series of experiments was carried out in which the heating coil was replaced by a semi-cylindrical piece of iron about 3.75 cm.long by 1.9 cm. in diameter covered round the circum-ference with thick asbestos cloth (No. 1 iron block). Running down the centre of the flat surface and about 0.08 cm. under the surface was a small hole to carry the thermo-couple. The block was hung by two platinum wires from a stand. It was then heated until about 50° above the required temperature when th 1008 McDAVID THE TEXPERATURES OF blowpipe was removed and bubbles of gas were brought into con-tact with the red-hot surface while the latter was cooling. When the temperature became too low for ignition t o take place the block was simply heated again and the procedure carried out as before until a sufficient number of readings had been obtained.An improvement was made in No. 2 block by boring a small hole in the centre of the flat face. By this means the thermo-couple became exposed to the air and since i t lay close to the surface i t ought to give a comparatively true figure for the temperature of the igniting surface. Tables V-VTII give com-parative results found by the above three methods. TABLE V. Contp-ison of Iroii Block and Electric Coil Mvtlzod with 13.5 per c e t t t . Coal Gas-Air illixtm-e. Electric coil method. Iron block (No. 1-Block) method. f - /-A Temper- No. of Temper- No. of atlure. rcdings. Result. atnre. ~.i.adings. Result'. 770" 775 7 SO 7 SO 785 786 790 790 795 800 :3 2 4 2 1 1 1 3 1 1 3 , Ignition KO ignition Ignition No ignition 1 gnit,ion 7 7 720" 730 710 750 760 765 7 70 790 800 810 1 2 2 1 1 1 2 2 1 > No ignit,ion Y 1 7 7 7 7 Ignition 9 7 Y 9 I 7 ? Y 810 1 7 7 -Temp.of ignition = 785" Temp. of ignit,ion == 760". TABLE VI. Cornprison of Electric Coil and Iron Block Method 15 per cent. of Hydrogen with Air. Electric coil. , Tern- NO. of per- read-ature ings. Result. 690" 2 Ignition 685 2 f ? 680 3 7 7 676 2 7 , 675 3 No ignition 070 4 ? ? 666 1 Y7 GOO 1 7 7 Temp. of ignition = 680". No. 1 iron block. No. 2 iron block. / -. 7-Tern- No. of per- read- per- read-atare ings. Result. ature ings. Result,. 750" 6 Ignition 705" 2 Ignition 710 9 7 7 700 4 7 Y 705 3 7 7 695 3 9 7 705 3 No igiiitioii 090 4 7 9 700 7 Y7 685 3 7 7 696 3 7 ) 680 2 3 , 090 3 7 7 680 0 No ignition Tern- No.of 676 2 ? ? A70 6 7 7 G G 6 1 7 7 Temp. of ignition= 705". Temp. of ignition= 085. IGNITION OF GASEOUS MIXTURES. 1009 TABLE V I I . Mixticre of Two Volumes of HydrogeIL wiih Five VolunLPs of Air: Two Series Carried Ozit with A'o. 2 Iron Block. Temper-ature. 730" 720 715 710 705 700 700 695 690 685 680 No. of readings. 3 3 1 2 1 1 1 3 1 1 I No igizitjioii Temper-ature. 730" 725 720 715 710 700 695 690 685 tj 80 670 No. of readings. 2 1 3 1 ti 2 3 4 1 2 1 Result. Ignition 9 9 9 1 9 9 ) No ignitioii Temp.of ignit.ion = 700". Temp. of ignition = 700". TABLE VIII. C'onapariso?z of Elect?-ic Coil arid Iron Block Methods 13.5 per cent. Mixtitre of Coal Gas with A i r . Electric coil. No.1 iron block. No. 2 iron block. h h r- > 7- c , Tern- No. of Tem- No. of Tern- No. of pera- read- pera- read- pera- read-ture. ings. Result. ture. ings. Result. ture. ings. Result. 786" 6 Ignition 810' 6 Ignition 800" 3 Jgnition 782 3 9 ) 805 1 9 9 795 1 Y Y 780 3 Y Y 800 1 Y > 790 3 7 Y 775 3 9 ) 795 3 Y Y 785 2 Y 9 775 1 KO ignition 795 2 No ignition 780 2 Y Y 772 2 Ignition 790 1 Ignition 775 2 > Y 773 5 No ignition 790 3 KO ignition 770 3 9 9 770 3 9 7 785 1 9 9 770 1 No ignition 768 3 9 780 4 9 765 3 Ignition 765 1 Ignition 775 3 Y 9 765 3 No ignition 765 3 No ignition 760 3 9 9 760 1 9 9 755 1 Y 9 750 2 9 9 Temp.of ignition= 775". Temp. of ignition= 795". Temp. of ignition= 765". .-From the results given i n tables 11-VIII it will be observed that the method gives a very sharp ignition-point and since the time taken to determine the temperature of ignition of any mix-ture was only about fifteen minutes i t is evident that f o r purposes of comparison a t least the method is very suitable. It will also be noted from the above results that the concentra-tion of the explosive gas has within the explosion limits no effect 011 the temperature of ignition. As however. the rate of cooling in the iron block method wa 1010 McDAVID THE TEMPERATURES OF very rapid the method was not very satisfactory for the purpose of obtaining absolute values.Accordingly it was discarded in favour of the method first described. Even in this method there are several factors that may affect t'he absolute value of the results whilst in no way affecting their comparat'ive value. These factors are the cooling effect of the bubble the presence of moisture in the gases the catalytic action of the platinum wire and the size of the silica tube. Dixon and Coward (Zoc. cit.) showed that the presence of moisture did not affect the ignition-temperature in the case of hydrogen and oxygen and in several other cases the difference was very small. The cooling effect of the bubble need not be taken into account, as its mass was very small compared with that of the heating source.Moreover although it was found that variations in the size of the bubble gave small differences in temperature this was probably due to a different cause which is explained later. The chief defect in this method lay in the fact t,hat the tempera-ture registered by the thermo-couple was probably slightly lower than that of the coil since the former was separated from the coil by the thickness of the silica and a volume of air. It is of course, obvious that the thermo-junction ought t o be near to the centre of the tube and that the coil must be as evenly wound as possible, so that there may be no unequal heating. I n order to study the effect of the size of the silica tube on the temperature recorded by the t'hermo-couple and if possible to obtain absolute values for the temperature of ignition of various gases a large number of determinations was carried out.For this purpose the gases employed were obtained in as pure a state as possible and on analysis gave the following result6 : Per cent. Hydrogen .............................. = 94.0 {zg = 6.0 ..................... Carbon monoxide Ethylene ................................. ............... C2H4 = 0.31 H = 1.43 N = 2.40 Methane (natural gas) I n making up the gaseous mixtures allowance was always made for the quantity of air present in the gas IGI.NI!CION OF GASEOUS MIXTURES. 1011 Table IX gives the dimensions of the various silica tubes employed in the determinatiolns. These were drawn out as evenly as possible from ordinary silica tubing. The experiments were carried out in the same manner as before, except that the ends of the silica tubes were in all cases stopped up with asbestos fibre so as t o diminish loss of heat within the tube by convection.Platinum and Eureka resistance wire were employed for making the ignition coils. The results found for hydrogen are given in table IX. TABLE IX. Showing No. of tube. 1 2 3 4 5 6 7 8 9 10 Bffect of the Size of the Silica Tube o n the Temperature of Igiiition of Hydrogen. Temperature of ignition of 20 per cent. of hydrogen in air using Thickness of wall of tube. 0.055 0.035 0.030 (em. 1 0.0425 0.030 0.035 0.035 0.0276 0.0225 0.025 Internal diameter . (cm.) 0.1575 0.1475 0.12 0,0775 0-075 0.075 0.095 0.0775 0.065 0.065 Length.(em. 1 6 6 6 6 3 6 5.5 6.0 4.0 4.0 Platjnum Eureka wire. wire. 682' 712" 688 712 { %} -{Z} -- 735 - 735 735 758 735 -It will be observed in the first place that for the same tube the figures found by using platinum are higher than those obtained when using Eureka wire indicat!ing a catalysing effect in the case of the latter. It is however probable that both substances exert a catalytic influence. It will also be noticed that as the thickness of the wall and the internal diameter of the silica tube decreased the temperature of ignition increased. It was not found possible to make tubes of smaller size than No. 9 and it was therefore impossible to say whether o r not the temperature given by No.9 were a maximum. It seemed prob-able however that the temperatures found when using this tube were very near t o the actual temperature of the heating coil. Accordingly this tube wound with platinum wire was used t o R R 1012 McDAVID THE TEMPERATURES OF determine the temperatures of ignition of other gases and the results found are summarised below : Hydrogen-air .................. 758" Carbon monoxide-air ......... 910 Ethylene-air ..................... 895-905 Coal gas-air ..................... 850 Petrol-air ........................ 960 Methane-air ..................... No ignition below 1000". In tables I and I1 the ignition-temperature of methane in air was found t o be 880-885O but. the gas probably contained a con-siderable quantity of hydrogen.I n order to verify this supposi-tion the effect of adding different proportions of hydrogen to methane-air mixtures was studied with the following results : TABLE X. Showing Effect of Hytlrogeu on the Temperature of Ignition of Methane and Air. Gaseous mixture. Temperature of ignition. 1000 ) hydrogen ............... 796" I 1 1000 C.C. methane 8000 , air 1500 C.C. methane 8000 , air 1850 C.C. methane 8000 ? air 500 ,) hydrogen ............... 836" 150 ,) hydrogen ............... No ignition up to 970". It is thus evident that pure methane when mixed with air does not ignite below 1000°. This fact is interesting and receives some confirmation from a statement in Brunswig's " Explosives " (English edition p. 55) in which it is stated that in the case of methane and air there is delayed ignition at 600° t o 7005 but that instantaneous ignition does not take place below 1000°.The foregoing experiments a1 t hough interesting were however, not quite conclusive but i t was hoped t l k t by making use of an instrument called the meldometer invented by Professor Joly, corroboration of the above results would be obtained. This instrument consists esseniially of an apparatus for measur-ing accurately the expansion of a platinum strip when subjected to heat. 'The strip which is held between two arms one fixed and the other movable is heated electrically and thus expands. Since the linear expansion in the case of platinum is almost directly proportional to the temperature i t is sufficient t o note the length of the strip at one or two fixed temperatures in orde IGNITION OF GASEOUS MIXTURES.1013 to find out by int)erpolation the temperature corresponding with any given length of the strip. Unfortunately the experiments carried out with this apparatus were unsuccessful. The strip was so very thin that when a bubble of the gaseous mixture was brought in contact with it slow com-bustion first ensued which raised the temperature of the strip until the latter glowed and thus exploded the residue of the gas. The method of standardising this instrument however indicated a method of standardising the apparatus used in the first series of experiments described herein. The apparatus finally employed, the method of standardisation and the results obtained are described below.The ignition apparatus in this final series of experiments con-sisted of a platinum coil wound regularly round two mica strips 3 cm. in length by about 0.3 cin. in width. These strips were notched along the edges so as to hold the wires in position whilst between them and thus insulated from the heating coil was placed a platinum-platinum-rhodium thermo-couple. The wire used for the heating coil was about 0*025 cin. in diameter and tlic pitch of the spiral was equal to about the diameter of the wire. Tho heating current was provided by storage batteries in order t o obtain no fluctuations in the temperature and the latter was varied by means of a sliding resistance. An ammeter was also placed in the circuit in order to measure the current.The thermo-couple which had previously been standardised against a standard thermo-couple was connected to a millivolt-meter. It will be noticed later however that i t was unnecessary to use a standardised thermo-couple; in fact it was ultimately found that no thermo-couple was necessary as the required results could be obtained by simply reading the ammeter. The apparatus was standardised in the following manner. Four salts the melting points of which were accurately known were selected and purified. A few crystals of each were ground to a powder and a small quantity of this powder was deposited on the platinum spiral. The current was then turned on and the coil heated the temperature being slowly raised until the salt just melted. A rough experiment was carried out first in each case to find out the approximate melting point the determination being then repeated several times with great care.It was found when the melting points of the salts were taken from time t o time during the experiments t h a t the readings on the millivoltmeter varied considerably but that the ammeter readings were practically constant for the same temperatura. R R" 1014 McDAVID THE TEMPERATURES OF The variation in the millivoltmeter readings may have been due to various causes for example the alteration in zero point of the instrument variation in room temperature or to the thermo-couple having been accidentally moved from the centre of the coil during the experiments. The ammeter readings theref ore, Temperature.Curve connecting ammeter readings with actual temperature. Standardised 1.5.16 and 2.5.16. only have been recorded. standardising the apparatus before and after use. Table XI gives the results obtained on TABLE XI. Ammeter readings. Before Before Potassium iodide . . . . . . 687' 3.74 3.76 A r -Salt employed. True m.p. experiments. experiments. Potassium bromide ... 723 3.90 3.90 Sodium chloride ...... 800 4.22 4-22 Potassium sulphate . . . 1072 5.45 5.47 The curve connecting the ammeter readings with the true Table XI1 gives the analysis of the gases employed. temperature is shown in the figure IGNITION O F GASEOUS MIXTURES. CO per cent. ...... 0, C,H . . . . . . . . co . . . . . . . . CH . . . . . . . . H . . . . . . . . 2 r . .. . . . . . . . . . . . . . . . . . . . . . TABLE XII. Analysis of Gases Used. Coal gas. Ethylene. Hydrogen. - - 0.26 0.47 4.53 94.0 9.84 50.30 33.00 - 95.8 1-60 - 6.0 4-2 - --- -- -- -1015 Carbon monoxide. ---97.5 ---2.5 I n table XIII the results found f o r the temperature of ignition of various mixtures of gases with air are given. I n cases where the gas contained air as impurity this was allowed for in making up the mixture. TABLE XIII. Zgnitiol2rtemperntures of Different Inflammable Gas-Air Mixtures. True temperature Mixture. Ammeter reading. of ignition. 15% coal gas-air .................. 4.59 S78" 10% ethylene-air .................. 5.12 1000 10 yo hydrogen-air ............... 4.00 747 Petrol (b.p. O-SO")-air ......... 5-10 985 Carbon monoxide-air ............ 4.82 931 Benzene-air ........................ 5.41 1062 Ether-air ........................... 6-27 1033 It was found that by enlarging the size of the bubble the mix-ture could be made to ignite a t an apparently lower temperature. This however was probably due to the fact that slow combustion of part of the gas took place a t the lower temperature and by heating the surrounding gas caused it to ignite without showing a corresponding rise on the ammeter. This ignition was as a rule quite perceptibly delayed. By reducing the size of the bubble t o about 3.7 cm. diameter instantaneous ignition occurred. The results given in table XIII are the mean oE a large number of experiments and experimental error can be t.aken as being less than + 3 O . The author wishes t o express his thanks t o Messrs. Nobel's Explosives Co. Ltd. for granting permission t o publish these results. NOBEL RESEARCH LABORATORIES, ARDEER STEVENSTON N.B. [Received September 6th 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101003

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

1016 MAXTED DISODIUM NITRITE AN ADDITIVE LXXX V II.-Da'sodiwn Nitrite an Additive Compound of Sodium Nitrite and Sodium. By EDWARD BRADFORD MAXTED. IN the course of work on the preparation of alkali metals by the elecrtrolysis of noii-aqueous solutions the author had occasion t o examine the products obtained by electrolysiiig a solution of sodium nitrite in perfectly anhydrous liquid ammonia. A deposit was observed to form on the cathode resembling metallic sodium in that i t dissolved in water with violent evolution of hydrogen, but completely differing from the metal by reason of its bright yellow colour and by its failure to dissolve in excess of ammonia with the production of the characteristic blue coloration. It was found further that the same compound may be obtained in a state of purity as a brilliant yellow precipitate by bringing together free metallic sodium and dry sodium nitrite each dis-solved separately in anhydrous amnionia.An analysis of the p r e cipitate showed i t t o possess the empirical composition Na2N0,, the ammonia acting merely as a solvent. By the action of water, decomposition takes place with regeneration of wdium nitrite and of sodium hydroxide. No hyponitrite could be detected in the solution. E X P E R I M E N T A L . Direct Prepration of Disodiurn Nitrite. For the preparation of the compound in a pure condition it is essential first of all to free the ammonia which is to be used as a solvent from all traces of moisture. This may be done by intro-ducing into a distilling flask a suitable quantity of liquid ammonia and dissolving in i t sufficient sodium to impart to i t a blue colour.The ammonia is freed from sodium hydroxide and from excess of sodium by distillation and recondensation in the vessel which is to be used f o r the preparation of disodium nitrite. The preparation may most conveniently be carried out by d i s solving in the clear anhydrous ammonia thus obtained a known weight of metallic sodium this being added in small pieces. Freshly fused and finely powdered sodium nitrite in a solid con-dition is next introduced. It is found unnecessary t o dissolve this separately provided that sufficient time is given for the sodium to pass into solution and that the nitrite is added gradually. The addition of sodium t o a solution of sodium nitrite on the othe COMPOUND O F SODIUM NITRITE AND SODIUM.1017 hand does not result in a satisfactory preparation on account of the formation of an iiisoluble layer round the sodium as added. The completion of the reaction is easily recognised by the dis chargg of the deep blue colour. This is found to take place on the addition of one molecule of sodium nitrite to each atom of sodium disodium nitrite being thrown down as a bright yellow precipitate from which the excess of ammonia is removed by evaporation. Any access of moisture is accompanied by an ex-plosion which is usually sufficiently intense to shatter the reaction vessel and to cause a dangerous spray of liquid ammonia. I n an experiment about 100 C.C. of pure anhydrous ammonia were condensed ,in the long-necked flask used as a reaction vessel.At this stage the rubber stopper at its mouth was withdrawn and replaced by a second one fitted with a Bunsen valve. One gram of metallic sodium was now introduced gradually in small pieces, the reaction vessel being allowed to remain for about ten minutes after the final addition t o ensure complete solution of the sodium. Three grams of finely powdered sodium nitrite previously dried by fusion were next weighed out in a small stoppered tube and added gradually to the solution of sodium the vessel being shaken gently. On adding the last portion of nitrite the blue coloration in the reaction vessel disappeared showing that one atom of sodium reacted with each molecule of sodium nitrite and a yellow precipitate of disodium nitrite was seen t o have formed.Ths reaction vessel was now removed from its cooling-hath and allowed to attain the ordinary temperature with consequent evaporation of the layer of colourless liquid ammonia with which the coin-pound was covered. At this point the reaction vessel together with its stopper and valve was weighed in order to ascertain whether ammonia was being retained as an integral part of the compound the following results being obtained : Grams. Weight of empty reaction vessel ........... 52-77 Weight of sodium nitrite added ............. Weight of sodium added ........................ 1.00 3-00 66.77 -Weight of vessel plus compound after evaporation of ammonia .................. 56.79 The yellow compound contains therefore no ammonia.Preparation. of Disodium Nitrite b y the Electrolysis of Sodium Nitrite. For this purpose a reaction tube about 35 cm. long and 3 cm. in internal diameter was provided wit.h concentric cylindrica LO18 MAXTED DISODIUM NITRITE ETC. platinum electrodes separated from one another by an asbestos diaphragm. 'The area of the electrode used as cathode was about 25 sq. cm. After half filling the electrolysis tube with pure dry liquid ammonia in the manner already described about 5 grams of dry powdered sodium nitrite were introduced and the whole allowed to remain. No metallic sodium was of course introduced into the electrolysis vessel. The two electrodes with their asbestos diaphragm were next introduced into the nitrite solution care being taken to avoid access of atmospheric moisture and a current of 2 amperes a t a potential of 110 volts from the laboratory mains was led through for one hour.On interrupting the current the cathode was seen to be covered with and surrounded by a yellow deposit similar to that obtained by the direct action of sodium on the nitrite. The platinum cathode was quickly immersed in a test-tube of dry ether and on bringing it under water the vigorous evolution of a considerable quantity of hydrogen was noted. A somewhat striking demonstration of the violence with which the compound combines with water was obtained by repeating the experiment and allowing the yellow cathodic deposit separated as far as possible from the ammonia to rise t o the ordinary temperature in contact with the air.A series of sharp decrepitations accom-panied often by fire was observed. Action of Water o n Disodium N i t r i t e . I n order to examine the moderated action of water on the compound 4 grams were prepared in a pure ammonia-free condi-tion by the first method. Hydration was now carried out by the passage of a current of moist nitrogen distilled water being added as soon as hydration was complete. The solution was found t o exert no reducing action on Fehling's solution sho'wing the absence of hydroxylamine and similar com-pounds. A second portion was tested for hyponitrite by neutral-ising with N/lOO-sulphuric acid followed by silver sulphate in accordance with the procedure recommended by Divers and Haga (T. 1899 75 97).No yellow precipitate of silver hyponitrite was obtained. A further sample was now neutralised without dilution with N/10-nitric acid and silver nitrate added. A white precipitate soluble irr much water was obtained. I n order to investigate the composition of this precipitate which was suspected to be silver nitrite a further 4 grams of disodium nitrite was hydrated in the manner previously described made up to approximately 100 c.c. and neutralised as before with N/10-nit3ri STUDIES IN THE PHENYLSUCCINIC SERIES. PART V. 1019 acid. The precipitate obt,ained by the addition of excess of silver nitrate solution was collected and carefully washed with cold dis-tilled water after which it was dried in a vacuum desiccator in the dark. A silver salt (2.1 grams) was obtained which was found on analysis to contain Ag=69*8; AgNO requires Ag=70.1 per cent. It is intended as soon as time permits t o investigate the whole subject more closely and to examine also the possibility of obtain-ing alkyl derivatives which may throw light on the constitution of disodium nitrite. CHARLES STREET, W AL s ALL. [Received September 13th 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101016

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

STUDIES IN THE PHENYLSUCCINIC SERIES. PART V. 1019 LXXXVIII. -Studies in the Phen ylsuccinic Acid Series. Part V. The Inter-conversion o f the Esters of r- and meso-Diphenylsuccinic Acids. By HENRY WREN and CHARLES JAMES STILL. IN the course of the earlier investigations on the optically inactive diphenylsuocinic acids i t was shown by Reimer (Ber. 1881 14, 1802) that these substances are mutually transformable. When the r-acid is heated with concentrated hydrochloric acid a t 200° the m eso-acid is quantitatively produced whilst the converse trans-formation occurs when meso-diphenylsuccinic acid is subjected to the action of an excess of barium hydroxide solution a t the same temperature. Somewhat later Anschiitz and Bendix (Annulen, 1890 259 91) found that a partial isomerisation takes place when the r-acid is heated with water alone at temperatures between 165O and 200° the meso-acid being formed to the extent of approxi-mately 30 per cent.The transition from the meso- t o the racemic series can be effected however under milder experimental condi-tions when the meso-acid is replaced by its ethyl ester as initial material; thus Anschiitz and Bendix (Zoc. c i t . ) showed that potass-ium r-diphenylsuccinate is the sole product of the action of alco-holic potassium hydroxide solution on ethyl meso-diphenylsuccinate, whilst when aqueous aIcoholic potassium hydroxide is employed a mixture of potassium 7- and meso-diphenylsuccinates is obtained (Wren and Still T. 1915 107 447). The experiments which are now described were undertaken with the hope of more definitely locating the phase a t which the chang 1020 WREN AND STILL STUDIES IN THE i 11 stereochemical configuration occurs.This might conceivably take place before during or subsequent to the actual hydrolysis. Experiments with the di-Z-mentliyl esters of meso- and Z-diphenyl-succinic acids (Wren and Still this vol. p. 531) made it appear probable that the change a t any rate in part precedes the hydro-lysis since it was found that the ester of the Z-acid is converted into that of the meso-acid when heated with aqueous alcoholic potassium hydroxide solution ; under similar conditions the ester of the meso-acid appeared t o suffer isomerisation but the nature of the product could not be definitely established. As these esters are not readily prepared in considerable quantity and as the cli-Z-nienthyl r-ester has not pet been obtained the work has been continued with the more readily accessible methyl and ethyl esters.When ethyl 1.-diphenylsuccinate is hydrolysed with a deficiency of aqueous ethyl-alcoholic potassium hydroxide solution the non-hydrolysed portion is found t o be composed of a mixture of ethyl T- and meso-diphenylsuccinates from which the latter can be readily isolated in the pure state; a similar mixture is formed under like conditioiis from ethyl mesodiphenylsuccinate and from this a pure specimen of the ethyl r-ester can be separated the slightly greater experimental difficulty in this instance being due to tlie relatively greater solubility of the racemic ester.Precisely similar phenomena are observed with aqueous methyl-alcoholic potassium hydroxide solution and the corresponding methyl esters. The pro-ducts of the hydrolysis have not been investigated with respect t o stereochemical configuration since they doubtless consist of mix-tures of potassium salts of the acids and acid estere the approxi-mately quantitative separation of which would be a matter of great difficulty. The experiments just described show that isomerisation a t any rate in part precedes hydrolysis; it may also take place to sGnie extent subsequently since potassium mesodiphenylsuccinate is partly converted into the salt of the r-acid when heated with aqueous-alcoholic potassium hydroxide solution. The change in the reverse direction appears to tak4 place far less readily under similar conditions and could not be definitely proved t o occur.Since i t was thus shown that the esters of the 1.- and meso-acids are interconvertible under the influence of alkali hydroxides it appeared of interest to e,xamine their behaviour in the presence of alkaline reagents under conditions which would preclude hydro-lysis. For this mason a series of experiments has been performed with solutions of sodium methoxide and ethoxide in methyl and ethyl alcohols respectively. The conversion of methyl and ethyl r-diphenylsuccinates into the corresponding m eso-esters can thus b PHENYLSUCCINIC ACID SERIES. PART V. 1021 readily effected ; the latter are considerably less readily soluble in these solvents than the former and the conditions can be so chosen that they separate from the solutions.I n tlhese circumstances iso-merisation proceeds approximately quantitatively. The reverse change can only be effected in much more dilute solution and the isolation of the r-esters involves a series of fractional crystallisa-tions. Lastly the conversion of ethyl 7'- into ethyl meso-diphenylsuccin-ate has been studied under somewhat diff erent conditions. During the last few years it has been frequently necessary to prepare r-di-phenylsuccinic acid and the process adopted has been that previ-ously described by us (T. 1915 107 446 et seq.) which consists in allowing ethyl phenylacetate and iodine to react in ethereal solution in the presence of solid sodium ethoxide and hydrolysing the mix-ture of ethyl r- and meso-diphenylsuccinates which is thus produced.11; has been noticed repeatedly that whilst the yield of r-acid is tolerably constant the proportion of r- to meso-ester produced in the different experiments varies within very wide limits. The ex-planation is now found to lie in tlie observation that ethyl r-di-plienylsuccinate is converted into the nzeso-ester when its ethereal solution is allowed to remain in contact with solid sodium ethoxide. From tlie theoretical point of view the interconversion of the esters in the presence of alkali appears to be most readily explained by the assumption of the formation of a coninion sodio-derivative wliich is decomposed by alcohol according t o tlie sclieme: C0,Et NaOEt t- -+ I PI,-C-H Na*E; Ph-& I Ph-6-H I %z Ph-C-H I E tO 11 C0,Et CO,Et C0,Et C0,Et I I I I H-C-Ph + Ph-C-13 Ph-C-H H -C-Ph I CO,Et h E t E X P E R I M E N T A L .Conversion of Ethyl r-Diphenylsuccinnte i n t o Ethyl mesoDipheny1-s uccina t e. A. By Partial Hydrolysis.-Ethyl r-diphenylsuccinate (0.8 gram) was heated under reflux during two and a-half hours with aqueous ethyl-alcoholic potassium hydroxide solution (0*316N 10 c.c.) ; th 1022 WREN AND STILL STUDIES IN THE solution was poured into water and the mixture extracted with ether. The crystalline residue left after evaporation of the solvent, melted a t 76-114O ; it was repeatedly crystallised from rectified spirit xhereby neiedles of ethyl mesodiphenylsuccinate melting a t 140-141° were readily isolated.B. By the Action of Sodium Ethoxide in Ethyl-alcoholic Solution. -Ethyl r-diphenylsuccinate (1.5 grams) was gently warmed in a small sealed tube with a solution of sodium ethoxide in absolute ethyl alcohol (0*32N 10 c.c.) until an almost clear solution was formed; on cooling the contents of the tube set to a stiff paste, which did not change in appearance wheln preserved for eight days a t the temperature of the laboratory. The solid was filtered washed successively with alcohol water dilute hydrochloric acid water, and alcohol and dried. It weighed 1.4 grams and melted sharply a t 140-141°. The melting point remained unaltered when the substance was crystallised from rectified spirit; it was further iden-tified as ethyl mesodiphenylsuccinate by the mixed melting-point method and by analysis.(Found C = 73.5 ; K = 6.8. Calc. C = 73.6 ; H= 6.8 per cent.) The filtrate from the original crop was diluted with water when a small amount of solid was precipitated which melted indefinitely a t 78-128O. C. B y Solid Sodium Ethoxide.-Finely divided dry sodium ethoxide (prepared from 1 gram of sodium) was allowed t o remain in contact with a solution of ethyl r-diphenylsuccinate (1 gram) in anhydrous ether (20 c.c.) a t the temperature of the laboratory during twenty-four hours. Water was then added whereby two clear solutions were formed; the aqueous portion was once ex-tracted with ether and the ethereal solutions were united and dried over calcium chloride. The residue obtained after removal of the solvent melted a t 75-110° and after being twice crystallised from rectified spirit yielded pure ethyl mesodiphenylsuccinate.The latter melted a t 140-141° and the melting point remained un-changed when i t was mixed with an approximately equal quantity of the synthetic ester. Con u er s ion of E t 11 y 1 me so D i ph e ny lsucci IZ a i e in t o E t h y2 r- Diphenylsuccinate. A. By Partial Hydrolysis.-Ethyl mesodiphenylsuccinate (5.7 grams) was heated under reflux during two hours with aqueous, ethyl-alcoholic potassium hydroxide solution (0*156N 60 c.c.). The resulting solution was evaporated nearly to dryness the residue diluted with water and shaken with a large volume of chloroform. The extract was dried over calcium chloride and the solvent re PHENYLSUCCIINIC ACID SERIES.PART V. 1023 moved. The residue melted a t 76-128O. It was digested with two successive small quantities of boiling light petroleum (b. p. 40-60O). [The part which remained undissolved by this treatment melted a t 133-136O and after being crystallised from alcohol yielded un-changed ethyl iizesodipheriylsuccinate rn. p. 140-141°.] The solu-tions were evaporated to dryness and the united residues extracted with alcohol; the more soluble portion after being crystallised from light petroleum (b. p. 40-60°) yielded ethyl r-diphenylsuccinate. The latter melted a t 83*5-84*5O and the melting point remained unchanged when i t was mixed with the synthetic r-ester. It was also identified by analysis. (Found C = 73.4 ; H = 6.7. Calc., C = 73.6 ; H = 6.8 per cent.) B.By the Action of Sodium Ethoxide in Ethyl-alcoholic Solu-tion.-Finely divided ethyl mesodiphenylsuccinate (5 grams) was shaken with a solution of sodium ethoxide in absolute ethyl alcohol (0*32N 85 c.c.) a t 70° during three hours; at the end of this period, the ester had completely dissolved t o a pale yellow solution which was then poured into a slight excess of dilute hydrochloric acid. The mixture was shaken with chloroform and the extract washed with aqueous sodium carbonate solution and dried over calcium chloride. The residue left after evaporation of the solvent melted at 76-128O. The mixture of normal esters after being treated as described in the preceding paragraph yielded unchanged ethyl mesodiphenyl~uccinate and ethyl r-diphenylsuccinate.The latter melted a t 83-84*5O and no alteration in the melting point was observed when it was mixed with an approximately equal amount of the synt'hetic r-ester. Conversion of Methyl r-Diphenylsuccinate into Methyl mesoDiph en y lsu c cinat e . A. By Partial Hydrolysis.-Aqueous methyl-alcoholic potassium hydroxide solution (0*874N 12 c.c.) was added to a boiling solution of methyl r-diphenylsuccinate (3 grams) in methyl alcohol (200 c.c.) and the mixture heated under reflux during four hours. The alcohol was removed by evaporation and the residue treated with water and a large volume of chloroform. The product obtained after desiccation of the chloroform solution and removal of the solvent melted a t 168-202O. It was twice crystallised from acetone when methyl mesodiphenylsuccinate was isolated in well-defined needles which melted a t 219-220O.No depression of the meltJng point was observed after admixture with the synthetic meso-ester. The substance was further identiiied by analysis. (Found C=72*6; H=6*2. B. By the Action of a Methyl-alcoholic h'olutiom of Sodium Calc. C=72.5; H=6.2 per cent. 1024 WREN AND STILL STUDIES IN THE Methozide.-Methyl r-diphenylsuccinate (1 gram) was suspended in a solution of sodium methoxide in absolute methyl alcohol (0-301N 50 c.c.) and heated a t 50-60° during eleven hours; the ester did not immediately dissolve but after about three hours, the nature of the precipitate was observed to have changed the platelets being replaced by a quantity of very fine needles. After cooling the precipitate was removed well washed with water and crystallised from a considerable bulk of acetone ; well-formed pris-matic crystals of methyl mesodiphenylsuccinate were thus obtained which melted a t 218.5-219*5°.The melting point was unchanged when the substance was mixed with the synthetic mesoester. At the ordinary temperature the change proceeds very slowly, doubtless owing to the comparatively sparing solubility of the r-ester in methyl alcohol. When the ester and alkali solution (approx. 0.25lv) were used in the proportion of 1 gram to 20 c.c., no change appeared to have taken place after nine days; after three months however tho formation of the nzeso-ester could be definitely established. Go I I ilersion of McthyE mesol)ilrT~e?Lyls.zLccinn t e into Me i h y l r-Biphenylsuccinate.A. By 1’urtiul lf yddysis.-Methyl mesodiphenylsuccinate (3 grams) was partly suspended and partly dissolved in boiling methyl alcohol (380 c.c.); 5 C.C. of aqueous methyl-alcoholic potassium hydroxide solution (0.681) were added and the mixture was boiled for an hour. A further portion of the alkali solution (5 c.c.) was then added and the heating was continued for a further period of five hours. At the end of this time the ester had com-pletely passed into solution. The alcohol was removed and the residue shaken with chloroform and water. The mixture of esters obtained lrom the chloroform solution melted a t 158-196O; it was fractionally crystallised from acetone. Unchanged meso-ester was isolated from the less soluble portion whilst methyl r-diphenyl-succinate was obtained by repeated crystallisation of the more soluble part from a considerable bulk of methyl alcohol.The latter was identified by crystalline form melting point (173-174*5O), niixed melting point and analysis. (Found C = 72.3 ; H = 6.1. Calc. C= 72.5 ; H = 6.2 per cent.) B. By t h e Action of a Solutioqz of Sodium Methoxicle in Methyl A IcohoZ.-Finely divided methyl mesodiphenylsuccinate (2 grams) was heated in a stoppered flask during ten hours a t 60° with a solution of sodium (0.9 gram) in absolute methyl alcohol (ZOO c.c.). A small portion remained undissolved. The mixture was exactl PHENYLSUCCINIC ACID SERIES. PART V. 1025 neutralised with dilute hydrochloric acid and the alcohol removed on the water-bath.The residue was treated with warm water and the part which remained undissolved was removed and dried The mixture of normal esters thus obtained melted indefinitely a t 162-182O. It was separated by systematic treatment with acetone and methyl alcohol as described in the preceding paragraph into unchanged methyl mesodiphenylsuccinate and methyl r-diphenyl-succinate the melting points being 218*5-219v50 and 174-175O respectively. A c t i o n of an Excess of h’tltyl-alcoholic Potassiurti Hydroside Solutioii o n r- and meso-Di~henyl.szcccinic Acids. nzesoDiphenylsuccinic acid (1 gram) was heated under reflux with a solution of potassium hydroxide in absolute ethyl alcohol (0*8AT 25 c.c.) during four hours. The substance dissolved slowly, complete solution being ultimately obtained.Excess of alkali was exactly neutralised with hydrochloric acid. The alcohol was removed by evaporation; the residue was dissolved in a small volume of water and treated with a slight excess of a hot solution of barium chloride. On cooling a crystalline precipitate of barium r-diphenylsuccinate separated from which the corresponding acid was isolated; i t melted a t 181-182° resolidified and again melted a t 219-220°. Unchanged mesodiphenylsuccinic acid melting and decomposing at 229-230° was obtained from the filtrate from the crop of barium salt. r-Diphenylsuccinic acid (1 gram) was heated under reflux with ethyl-alcoholic potassium hydroxide solution (O.SiV 25 c.c.). The product was treated exactly as described in the preceding para-graph. Unchanged T-acid was readily isolated from the correspond-ing sparingly soluble barium salt the mother liquors from which, however did not yield rnesodiphenylsuccinic acid in recognisable amount. The authors desire to express their thanks to the Research Fund Committee of the Chemical Society for a grant which has defrayed part of the cost of the investigation. PURE AND APPLIED CHEMISTRY DEPARTMENT, MUNICIPAL TECHNICAL INSTITUTE, BELFAST. [Received October loth 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101019

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

1026 REILLY AND HICKINBOTTOM : LXXXI X .- Derivatives of n- But ylaniline. By JOSEPH HEILLY and WILFRED JOHN HICKINBOTTOM. THE lower nlkylanilines have for a long period been recognised as of considerable technical importance and with their derivatives have been subjected to very detailed investigation. On the other hand, the higher alkylanilines and phenylenealkyldiamines generally have been but little examined and it is only quite recently that such compounds as p-nitrosodipropylaniline pphenylenedipropyldiamine (Jacobs and Heidelberger J. Bid. Chem. 1915 21 103) and pphenyleneisoamyldiamine (Karrer Ber. 1915 48 1398) have been subjected t o any thorough study (compare also Mandl, Monatsh. 1886 7 99; Baeyer and Noyes Ber. 1889 22 2173). I n the case of the n-butyl compounds but few derivatives have been prepared.By oondensing 12-butyraldehyda with aniline Kahii (Ber. 1885 18 3361) obtained n-butylaniline and from it the nitrosoamine the acetyl compound and the hydrochloride but no other references to n-butylaniline or its derivatives have been found. I n the present work the condensation of n-butyl chloride and aniline has been investigated and several of the derivatives of n-butylaniline have been prepared and their properties investigated. I n the reaction between n-butyl chloride and aniline it was found that mono-n-butylaniline was the chief product when these com-pounds were heated together under atmospheric pressure. A frac-tion of higher boiling point was found to consist mainly of di-n-butylaniline. The crude mixture of bases resulting from the reaction was dis-tilled and thus partly separated into aniline n-butylaniline and di-n-butylaniline.The n-butylaniline fraction was converted into phenyl-n-butylnitrosoamine (I) which was reduced to as-phenyl-N(C,H,)*NO N(C,=S)*NH N( C,H9)*N :N*N(C,H,) /\ /\ /\ /\ I I - + I 1 - + I I t \/ (111.) \/ (11.1 x NH C,H NH*C,H V,H,)*NO /\ + \ I - 1 I \/ ‘ G ) \ \/ /\ ‘h6 NO 0 \/ NH2 (V. ) (IV.1 (VI. DERIVATIVES OF N-RUTYLANILINE. 1027 n-butylhydrazine (11) and this compound was 6hen oxidised to diphenyldibutyltetirazone (111) by the action of yellow mercuric oxide in ethereal solution : By means of Fischer and Hepp’s reaction (Rer. 1886 19 2991; 1887 20 1247) the nitrosoamine was converted into p-nitroso-n-butylaniline (IV).On keeping the crude hydrochloride darkened, owing probably t o the presence of free hydrogen chloride behaving similarly t o p-nitroeoisobutylaniline hydrochloride (Walker Anna-l e i ? 1888 243 298) p-Nitroso-n-butylaniline was easily reduced by means of zinc dust and hydrochloric acid to the corresponding diamine (V). The nitrosoamine is also decomposed into p-nitroso-phenol and n-butylamine thus confirming its constitution. It is converted into p-nitrosophenyl-?t-butylnitrosoamine (VI) by the action of nitrous acid. Whilst p-nitrosomethylaniline hydrochloride separated almost quantitatively in Fischer and Hepp’s reaction (Zoc. c i t . ) from solu-tion in a mixture of alcohol and ether p-nitrosobutylaniline hydro-chloride under similar conditions gave only a small precipitate (compare Walker Annnlen loc.c i t . ) . A yield equal t o 75 per cent. of the weight of nitrosoamine taken is obtained by substituting a solution of hydrogen chloride in butyl alcohol for the ethyl-alco-holic solution and reducing the proportion of alcohol t o ether by one-half. pPhenylene-77-butyldiamine resembled the other known mono-substituted ~~plien~lenediamines in being readily oxidised t o p-benzoquinone and in yielding colour reactions with ferric chloritle and nitrous acid (compare Fischer and Wacker Rer. 1888 21, 2614; Jacobson Annalen 1895 287 131 ; Bamberger Ber. 1898, 31 1516; Bernthsen and Goske Ber. 1887 20 929). E x P E R I M E N T A L. n-Butylaniline was prepared by heating one molecular proportion of aniline (93 grams) with slightly more than one molecular pro-portion of n-butyl chloride (100 grams) fo,r thirty-six hours on a water-bath using a reflux condenser.A crystalline deposit was pro-duced which after the liquid had been filtered off was shown to be mainly aniline hydrochloride with a small amount of n-butylaniline hydrochloride. From the reddish liquid poured off the crystalline deposit uncombined n-butyl chloride was removed by distillat.ion and the residual oil treated with sodium hydroxide solution. The bases which separated were extracted with ether the ethereal layer was left in contact with potassium carbonate for some time and the solvent removed by evaporat,ion ; the oil obtained was then distilled. At first’ some n-butyl chloride mixed with aniline distilled ove 1028 REILLY AND HICKINBOTTOM : below 180°.The fraction 1 80-200° contained n-butylaniline mixed with aniline and the distillate between 200° and 250° was n-butylaniline mixed with a smaller amount of a d i n e . There was also a fraction boiling a t 250-275O which was found to consist chiefly of di-72-butylaniline ; this was investigated later. The distil-late boiling a t 200-250° on redistilling gave a large fraction a t 240-245O and by a further redistillation this gave a fraction boil-ing a t 242-244O/765 mm. By converting the latter fraction into the nitrosoamine and reducing with zinc dust and warm glacial acetic acid n-butylaniline was obtained free from traces of the dialkyl compound. It boiled a t 241-242O/752 mm.(Kahn gives 235O/720 mm.) The fraction boiling between 200° and 250° from the original experiment with aniline and ?z-butyl chloride was not further frac-tionated for subsequeat experiments for the action of nitrous acid made i t possible to separate the mono-n-butylaniline from aniline and di-n-bntylaniline. Tlie fraction boiling between ZOOo and 250° (105 grams) was therefore dissolved in an excess of dilute hydro-chloric acid and a concentrated aqueous solution of sodium nitrite was slowly added until the yellow turbidity changed to red. The nitrosoanline separated on top of the aqueous solution as a reddish-yellow oil which was extracted with ether the ethereal solution being washed with sodium hydroxide solution and finally with water. From the separated ethereal layer dried over potassium carbonate the solvent was evaporated leaving the nitrosoamine as a greenish-yellow oil.From a portion (26.5 grams) of the oily frac-tion boiling between 200° and 250° referred t o above 22 grams of phenyl-72-butylnitrosoamine were obtained. This is insoluble in cold water very sparingly so in hot water soluble in strong acids, and in most organic solvents. A fresh solution in acid is precipi-tated by so'dium hydroxide solution. The nitrosoamine is volatile in steam collecting in the distillate as a pale yellow oil heavier than water (compare Kahn Zoc. cit. p. 3367). Both 12-butylaniline and phenyl-n-bntylnitrosoamine can be readily nitrated yielding in each case yellow crystalline nitro-com-pounds which are scluble in alcohol or acetone and insoluble in water but can be recrystallised from concentrated nitric acid.They were not further investigated. Phen yl-n-hut ylh ydraoine . Phenyl-n-butylnitrosoamine (20 grams) dissolved in glacial acetic acid (50 grams) was slowly added t o zinc dust (100 grams) sus-pended in 200 C.C. of 90 per cent. alcohol and the mixture was constantly stirred and kept a t 10--20°. When all the nitrosoamin DERIVATIVES OF N-BUTYLANILINE. 1029 had been added the mixture was heated to boiling and quickly filtered to prevent the deposition of crystals. The zinc dust was washed repeatedly with small quantities of warm absolute alcohol, the washings being added to the filtrate. This nearly colourless filtrate was rendered slightly acid by the addition of concentrated hydrochloric acid and then evaporated to a small bulk.During t'he evaporation the solution gradually deepened in colour until finally it became dark red. The concentrated solution of the hydro-chloride was next treated with excess of concexitrated sodium hydr-oxide solution until the precipitate first formed was completely re-dissolved. The crude base which separated as a dark red oir was extracted with ether the &hereal layer dried over anhydrous potassium carbonate and the solvent evaporated. The residual oil consisted chiefly of plienyl-wbutylhydrazine together with some ~~butylaniline. The yield of crude oil was usually 75-83 per cent. of the weight of phenyl-jt -butylnitrosoaniine used. I n order to separate the 92-butylaniline from the phenyl-rt-butylhydrazine the crude oil was dissolved in dry benzene and dry hydrogen chloride passed through the solution until there was no more absorption.The benzene solution a t first changed to a deep red but later i t became paler in colour with the formation of a turbidity. The' benzene solution was filtered and evaporated to a small bulk, when the hydrazine was precipitated as a pale yellow crystalline mass on the addition of dry ether. By washing the precipitate with a small amouiit of benzene the liydrazine hydrochloride was dis-solved leaving behind the ?z-butylaniline hydrochloride. The phenyl-n-butylhydrazinet hydrochloride was recovered from the benzene solution and twice more subjected to this treatment when i t was obtained pure. From chloroform the hydrochloride sepa-rated in white needle-shaped crystals which are very readily soluble in water benzene chloroform methyl or ethyl alcohols and very sparingly so in ether or light petroleum (b.p. 60-80°). It reduces Fehling's solution on warming : 0.1030 gave 12-65 C.C. N a t 2 1 . 5 O and 747.3 mrn.: N=14*01. 0.1244 , 0*0900 AgC1. C1=17*90. C,,H,,N,,HC'l requires N= 13.96; C1= 17.67 per cent. Treatment with sodium hydroxide solution and extraction with ether gave the base as an almost colourless oil. It boils a t 247-250°/ 762.7 mm. decomposing slightly with the evolution of * In the nitrogen estimations recorded in this paper the gas was measured over 40 per cent. potassium hydroxide solution. The pressures recorded have been corrected for vaponr pressure of the potassinm liydroxide solution 1030 REILLY AND HICKINBOTTOM : ammonia.Under diminished pressure the base. can be distilled unchanged. Diphen yldi-n- 6 u t yl t e trazo ?I e . The crude phenyl-n-butylhydrazine was dissolved in ether and yellow mercuric oxide gradually added following Fischer's method f o r the preparation of the tetrazone from phenylmethylhydrazine (Annalen 1878 190 108). The red ethereal filtrate obtained on separation from the mercuric olxide and mercury was evaporated under diminished pressure and on addition of aqueous alcohol the tetrazone was obtained in slightly yellow flattened needles. These crystals were dissolved in a small amount of aqueous alcohol (60 per cent.) and placed in a vacuum desiccator over calcium chloride until tho tetrazone separated in white shining plates melting at 72-73O.After melting and cooling the melting point was again determined and found to be 73O. On heating above its melting point however, the compound gradually darkened until at 110-120° there was an evolution of nitrogen the liquid became dark brown and did not solidify again on cooling: 0.0906 gave 13-22 C.C. N at 14'7O and 758-5 mm. N=17-28. C,,H,,N requires N = 17-28 per cent. An aqueous-alcoholic solution of diphenyldi-~~-butyltetrazone rapidly decomposed the solution changing first to a mauve colour, then gradually t o violet and finally to blue and indigo. The violet or blue solution was changed t o an indigo colour by means of acids, and t o a reddish-mauve colour having a blue fluorescence by alkalis, these changes being reversible.Zinc dust and acetic acid destroyed the blue colour. Concentrated nitric acid changed the colour to yellow whilst aqueous iodine solution produced a dirty green coloration. Lactic acid gave the indigo colour which by the action or" potassium iodide changed to olive green. Dilute potassium per-manganate was reduced. The addition of bromine in carbon tetra-chloride solution changed the indigo colour t o a brownish-yellow. pNitroso-n-bu t ylaniline. Phenyl-n-butylnitrosoamine was dissolved in about ten times its volume of dry ether and four times its volume of alcoholic hydrogen chloride were added. I n a few minutes the green solution became red and after some time small brownish-red crystals of p-nitroso-n-butylaniline hydrochloride were deposited which were collected, washed with alcohol then ether and dried.It was found that pnitroso-n-butylaniline hydrochloride was less readily soluble in n-butyl alcohol than in ethyl alcohol. A butyl-alcoholic solution of dry hydrogen chloride was therefore use DERIVATIVES O F N-BUTYLANILINE. 1031 instead of the ethyl-alcotholic solution. The nitrosoamine was dis-solved in twice its volume of dry ether and two volumes of a solu-tion of dry hydrogen chloride in n-butyl alcohol were added. After two hours a copious yellow precipitate of the hydrochloride had formed the deposition of which was accelerated by stirring. It was collected washed with alcohol and finally with ether. To a solution of the hydrochloride in water an excess of ammonia was added when the base was precipitated as a green turbid oil which was extracted with ether.The ethereal extract of the nitroso-derivative was washed once with water and the ether eva-porated leaving the base as a green dark liquid which solidified on cooling t o a blue shimmering mass. It was purified by dis-solving in alcohol and adding water until a turbidity was produced. After somet time the base crystallised in long flattened needles melting at 58-59O: 0.1173 gave 16.32 C.C. N at 22'0° and 742.7 mm. N=15*73. C,,H,,ON requires N = 15.76 per cent. By slow evaporation of the ethereal solution the compound crystallised in large steel-blue prisms. It is only sparingly soluble ill water or light petroleum but dissolves readily in ether benzene, or alcohol.Concentrated solutions are green whilst dilute solu-ticns are yellow. The solid although steel-blue when in crystalline form is green o r yellowish-peen when powdered or crushed. The hydrochloride crystallises from a mixture of alcohol and ether in yellow needles which are changed to red and finally to a very dark colour by traces of hydrogen chloride: 0.2386 gave 0.1588 AgCl. C1= 16.47. It is very readily soluble in alcohol water or acetone but insol-uble in ether o r light petroleum. By the action of dilute nitric acid on the dilute aqueous solution of the hydrochloride a yellow crystalline nitro-compound was pro-duced insoluble in water acid o r alkali but soluble in alcohol or ether. On crystallisation from hot aqueous alcohol it was obtained in long yellow needles but was not further examined.C,,E€,,ON,,HCl requires C1= 16.52 per cent. Decomposition of pNitroso-n- b ut ylaniline with A lkali. 2'5 Grams of p-nitroso-n-butylaniline were added t o 40 C.C. of a 10 per cent. solution of sodium hydroxide and the mixture was distilled in a current of steam f o r twenty minutes the distillate being collected in an excess of dilute hydrochloric acid. .The red-dish-brown residue was neutralised with dilute sulphuric acid until the colour became pale green when the solution was extracted wit 1032 REILLY AND HIC!KINBOTTORI : ether. On evaporation of the ethereal layer a pale buff-coloured residue was left which dissolved in alcohol acetone or ether to a green solution. By slow evaporation of the ether the compound was obtained in almost colourless needles melting and decomposing a t 120-123O.It had the properties of pnitrosophenol and gave a red sodium salt crystallising from water o r from alcohol in red needles extremely readily soluble in water and sparingly so in ether or acetone. (Found Na=15*44. Calc. Na=15*85 per cent.) The hydrochloric acid solution in which the distillate had been collected was evaporated to dryness leaving an almost white residue which was identified as )L-hutylamine hydrochloride by the analysis of the platinichloride. Calc. Pt = 35.10 per cent.) The production of the primary aliphatic amine and pnitrosophenol from the nitrosoarnine proves that the nitroso-group by the actiou of alcoholic hydrogen chloride had migrated to the para-position, behaving in a manner similar to that observed when the lower alkyl derivatives of aniline such as phenylmethylnitrosoamine are simi-larly treated.(Found Pt = 34.87, p2\ritroso-n-bzstylunili~ieiiitrosoanLili e . Two grams of p-nitroso-76-butylaniline hydrochloride were dis-solved in a small amount of dilute hydrochloric acid the solutioii was cooled in a fr,eezing mixture and a concentrated solution of sodium nitrite (a slight excess of 1 mol.) was added slowly. A greenish-yellow flocculent precipitate separated which was col-lected after an hour. It was purified by dissolving in alcohol and adding water until a turbidity was produced and then leaving tlie mixture until crystallisation had taken place. The compound s e p -rated in small green plates melting a t 39.5O: 0.0855 gave 14.85 C.C.N a t 16'8O and 754.0 mm. p-2\'itroso-n-but?/lan~Zi?~en itrosoanzine is freely soluble in most organic solvents but almost insoluble in water. Dilute solutions become bright yellow by the action of alkalis whilst acids almost discharge the colour these changes being reversible. It was found that the colour of an alkaline solution could be discharged by the addition of one drop of / 20-sulpliuric acid. The compound responded t o Liebermann's test for nitroso-compounds. N=20.33. C,,H,,O,N requires N = 20.29 per cent. 11- ~ V I c 11 yle I I P -11- 7) 11 tyMio n2 iii e . Zinc dust (15 grams) was added gradually to a solution of 11-nitroso-n-butylaniline hydrochloride (10 grams) in water when a fairly vigorous reaction ensued attended by evolution of heat s DERIVATIVES OF N-BUTYLANILINE .1033 that i t was necessary to cool the mixture. After the reaction had moderated concentrated hydrochloric acid (45 c.c.) was gradually added and the mixture was heated for a short time on the water-bath until almost colourless. It was filtered hot from the excess of zinc dust which was washed repeatedly with warm dilute hydro-cliloric acid and finally with alcohol. The acid filtrate was then evaporated to about half i h bulk rendered alkaline with sodium hydroxide solution and the base which separated out as a dark-coloureld oil was extracted with ether. p-Yheihyleti e-n-b ittyldicimitre was obtained in a pure condition by the addition of an excess of dilute sodium hydroxide solution to a concentrated aqueous solution of the liydrochloride cooled in ice.The base separated as a white, ciystalline solid which was collected and washed with water. On recrystallisation from light petroleum it was obtained in white plates melting a t 31*5O having a pearly lustre. The colour slowly changed t o red on exposure to a i r : 0.0631 gave 9-45 C.C. N a t 1 8 . 5 O and '744.5 nini. An alternative method of obtaining the free base in a pure con-dition was also employed. The dark-coloured base was distilled instead of being converted into the hydrochloride. Under a pres-sure of 768 mm. it distilled over mainly a t 302*5-303*5O and on cooling solidified t.0 a white crystalline mass. It is readily soluble in most organic solvents but moderately so in cold light petroleum, and insoluble in water.p-PA enyl e tl e-n- b tctgldinnt i r i e dihydrochloride crystallised from l i d absolute alcohol in small glistening plates which did not melt a t 2ooo : N=l7*19. C,,H,,N requires N = 17.07 per cent. 0.0750 gave 7.80 C.C. N a t 20° and 746.3 mm. 0'1324 ) 0'1610 AgC1. C1=30.08. C,,H,GN,,2HCl requires N = 11.82 ; C1= 29-90 per cent. It is insoluble in ether sparingly soluble in cold absolute alcohol, more readily so in hot alcohol and very readily soluble in water. With a small amount of ferric chloride solution a neutral solution oE the hydrochloride gave a dirty green coloration which changed slowly through a succession of colours t o a dark red. The greeii colour was rejtored 011 adding inore lerric chloride.With potassiuni ferrocyanid e the hytlrochloride solution became olive-green chang-ii;g to blue on the addition of alkali. Oxidation by boiling with ferric chloride or potassiuni dicliromate and dilute sulpliuric acid produced an odour resenibliiig that of p-benzoquiaone. A solution of bromine in aqueous potassium bromide gave a yellow precipi-tate which gradually darkened on keeping. N = 11.90 1034 DERIVATIVES OF N-BUTYLANILINE. D i m o tisatio tz of p-Phenylene-n-b utyldiamin e Dihydrochloride . To an aqueons solution of the hydrochloride (1 mol.) rendered acid by the addition of hydrochloric acid (3 mols.) and cooled in a freezing mixture an aqueous solution of sodium nitrite was added until there was a slight excess of nitrous acid present.On first adding the sodium nitrite the hydrochloride solution became green and then rapidly turned to a brown tint. pAminodiphenylamine behaves in a somewhat similar manner (Jacobson loc. cit.). On adding this diazotised solution to an aqueous solution of platinic chloride a light yellow precipitate of the diazonium platinichloride was obtained which was collected and washed well with water and finally with alcohol and ether: 0.1888 gave 17.50 C.C. N a t 12O and 758.7 mm. 0.1509 , 0'0381 Pt. Pt=25*25. N=11*08. (C,oH,,N,Cl),PtC14 requires N = 11-05 ; Pt = 25.66 per cent. This salt was almost insoluble in water but spasingly so in alcohol. It commenced to darken a t 115-120° and decomposed a t 147-150° with a brisk evolution of nitrogen. When heated suddenly in a Bunsen flame it decomposed explosively. On the addition of an aqueous solution of the diazonium chloride, freed from nitrous acid by means of carbamide t o an alkaline solu-tion of &naphthol an azo-compound separated as a red crystalline powder which was collected after a few hours. I n the dry condition it is almost black and has a metallic lustre. It is insolub'le in water, but soluble in most organic solvents and dissolves in concentrated sulphuric acid giving a deep red colour. An acetylacetone deriv-ative was obtained 2s an orange precipitate on adding a solution of the diazotised pdiamine free from nitrous acid to art- alcoholic solution of acetylacetone. On the addition of sodium acetate there was a yellow turbidity from which crystals soon separated. The compound crysitallised from aqueous alcohol in yellow needles but, was not further examined. [Received November lst 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101026

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

BLOUNT THE LIMITATIONS OF THE BALANCE. 1035 XC.-The Limitations of the Balance. By BERTRAM BLOUNT. ABOUT three years ago the author had occasion in the course of a research to make accurate weighings extending over some months, The balances used were by the first makers and the discrepancies observed were at first attributed t o the errors of experiment arising from the difficulties of the research. Slowly and reluctantly how-ever the conclusion was drawn that the errors lay in the balances themselves and the following is an account of the nature and extent of these errors. It is usually accepted that a good balance carrying 200 grams in each pan should turn with certainty with 0.1 milligram an accuracy of one part in two millions. Much higher accuracies have been claimed but f o r the purpose of the research in question this degree of accuracy was sufficient.It was assumed that it could be obtained without difficulty and the research was started on this assumption. As has been mentioned above the cause of the error was not a t first suspected and after many months of work the balances themselves were critically tested. It may be stated a t once that all were usually accurate over a short period of a few hours or even a few days but over longer periods of a few weeks or months they showed themselves untrustworthy. In all six balances were used three being provided by the kind-nem of Professor Pope a t Cambridge; the other three were a t the laboratory in the author's house. Those a t Cambridge were a Sartorius carrying 200 grams in each pan a smaller Sartorius carrying 100 grams in each pan and a Bunge preferred by the late Prof.Ewing for his own work carry-ing 100 grams in each pan. Those in London were an Oertling-carrying 200 grams in each pan (and it may be remarked that the beam used was selected out of five by the makers as the best tihey had) another Oertling with a load of 100 grams and a modern Bunge carrying 200 grams. Each balance could be read with accuracy to 0.1 milligram and in all cases standard weights were used. All proper precautions were taken to secure uniformity of condition. Four of the balances were used in their own case one in a massive gun-metal case which was air-tight and one in an all-glass case which was also air-tight. I n each case twin weighh were used so as to prevent errors creep-ing in from this cause.VOL. UXI. s 1036 BLOUNg! THE LIMITATIONS OF THE BALANCE. Tenths - Date. Left. Right. Temp. mg. Weighings were made by three independent observers a t both Cambridge and London and as there were far too many to record in full in a short paper only those representing the maximum variations are recorded and are as follows: Tenths Pate. L m h t . Temp. CAMBRIDGE. 29.4.17 4 15.5" -C- - 0 30.4 17 5 2 i 15 + 0 30.4.17 5; 5 15.5 4 2.5.17 2+ 3 14.5 - 4 7.5.17 7 6 13.5 + 1 10.5.17 4; 6 13 - 14 11.5.17 5 44 14 -+ 4 12.5.17 2 3 14 - I 2.5.17 7 5& 14 - 1 i 22.5.17 7 7 16.5 & 0 24.5.17 6 7 15.7 - 1 31.5.17 8 5 17 1 1 1.6.17 3 4 17 - 1 3.6.17 6 5 17 A- 1 11.7.17 7 78 15 - 1 Small Snr t o ri,ic s .Divisions. Divisi o m . Tenths -(7 Tenths 12.7.17 9 8 16" 12.7.17 2 5 16 13.7.17 7 5 16* 12.7.17 2 2 16-5 13.7.17 4 5 16.5 13.7.17 2 2 16.5 13.7.17 1 3 16.5 17.7.17 3 3 l i - 3 20.7.15 14 3 18 29.7.17 5 5 19 3.8.17 54 6 1 7 12.8.17 6 5 17.7 18.8.17 3 20.8.17 ;# 30.8.17 8 16 Date. 29.4.17 30.4.17 5.5.17 5.5.17 6.5.17 7.5.17 11.5.17 18.5.17 27.5.17 29.5.1'7 31.5.17 4.8.17 10.6.17 14.6. I 7 15.8.17 li.6.17 21.6.17 22.6.17 Right. 6 2 c 84 5* 2 2 54 7 3+ 7 23 74 5 4 53 3 3* 3t Temp. 15.5' 15 15 15 14 14 14 14.5 17 17 17.3 17 17.5 18 18.5 19 19 18.5 Date. Left. Right. Temp. 26.6.17 3* 31- 17.5' 4.7.17 5 16-5 29.6.17 44 5 17* 5.7.17 t4 3& 16.5 7.7.17 4 3 17 9.7.17 6 64 16.5 12.7.17 44 4+ 16.5 15.7.17 5 4 t 18 19.7.17 !& 7 18 20.7.17 29.7.17 4 P ::.5 1.8.17 7 7 17.7 6.8.17 7* 9 17.5 11.8.17 3 17.5 20.8.17 3* 24 17.5 30.8.17 7 Sf 16.5 13.8.17 !' 58 18 Greatest differonce in 4 mont,hs 0.6 milligram.* Full. t Rare. Bmge Date. 29.4.17 30.4.17 I .5.17 1.5.17 4.5.17 7.5.17 10.5.17 12.5.17 13.5.17 14.5.17 26.5.17 28.5.17 29.5.17 7.6.17 14.6.17 17.6.17 18.6.17 19.6.17 22.6.17 26.6.17 Temp. mg. 15.5' -+ 0 15.5 - 1 14.5 - 3 14.5 f 0 13.5 - 14 15 - 34 13 - 8 14 - 14 15 - 4 15 -16 -16-75 - 1 16.25 + 0 'B 17 1- 14 \- 1 18 & 0 18.75 - 3 19 -+ 3 19 & 0 17 - 2 18 - 1 BLOUNT THE LIMITATIONS OF Date.28.6.17 5.7.17 6.7.17 13.7.17 19.7.17 12.7.17 23.7.17 26.7.17 29.7.17 ;:% 4.8.17 6.8.17 9.5.17 11.8.17 13.8.17 19.8.17 21.8.17 25.8.17' 1.9.17 31.8.17 Large Sartorius. Divisions. Tenths I L x a t . Temp. mg. 4 4 24.5" f 0 4& 79 21.9 - 6 3 3 16-3 0 5 7 18.2 - 4 3 34 16.7 - 1 Right. 7 6 9 7 6 6 4 69 99 94 7 10 6 6 ) 51 94 7 2 10 5 Date. 26.7.17 7.8.17 4.9.17 10.9.17 14.9.17 THE BALANCE. 1037 Divisions. L Tenths Lift. 9 9 6 1 P ;* 7 5 4* 10 12 12 12 12* 12 12 12" 13 94 Right. Temp. 10 17" 10 16 8 16 4 16.5 7Q 16.5 9* 18 8* 18 5 19 8 19 8 17 3 17 z y :;.5 - 1 17 - 6 17 - 7 17 - 8 17 -11 16 -11 16 Greatest difference 2.5 milligrams in 4 months.Rejecting the readings after 4.8.17 0.45 milligram in 3 montha. * F~dl. 7 Bare. Date. 16.6.17 19.6.17 23.6.17 3.7.17 7.7.17 20.7.17 Date. 14.6.17 15.6.17 16.6.17 30.6.17 10.7.17 14.7.17 16.7.17 26.7.17 27.7.17 2.5.17 Divisions. A-Left. Right. 4 4 1 3 2 3 3 8 7 lo* 6 64 F 1 ;i 3 2 1+ Bunge. Tenths Temp. mg. 24" & 0 19.5 - 4 21.5 - 2 13.5 -10 16 - 7 22 - 1 20 - 5 21.5 + 2 -21 .- 3 15.5 .- 9 Date. 4.8.17 5.8.17 8.8.17 20.8.17 22.8.17 26.8.17 6.9.17 9.9.17 13.9.17 Divisions. +- Tent,hs Left. Right. Temp. mg. 0 34 22" - 7 1 9 20.3 -16 6 20.3 - 5 7 20.4 -12 5 18 - 8 ? 1 1.6 milligrams.Divisions. - Tenths Left. Right. Temp. mg. 6 94 16.5" - 7 3 8 18 -10 :* 54 19-5 18.5 - - 1 74 ti 20.5 +- 2 5 8 18 - 6 64 74 20 - 2 0 2 20 - 4 5 8 17 - 6 Greatest difference in 3 months. 1-2 milligrams. s s 1038 BLOUNT THE LIMITATIONS OF THE BALANCE. Small Oertling. Divisions. - Tenths Date. Left. Right. Temp. mg. 30.6.17 34 2 14 4- 3 14.6.17 6 5 2 4 O * 0 Divisions. - Tenths Date. Left. Right. Temp. mg. 1.8.17 24 3 16" - 1 2.8.17 44 3& 16.5 + 2 8.8.17 2& 24 20.51 10.8.17 2 2 19 = (' (From 16.8.17 to 22.8.1 7 balance remained constant (left and right equal) (From 6.8.17 to 1.9.17 the halaiicc did not vary more than & division with with variations of temperature of 3".) variations of temperature of 4.2".) 1.9.17 3; 9 + 2 ' 14.9.17 9 84 18.3 + 1 6.9.17 24 i! & 0 I Greatest difference in 3 months 0.4 milligram.These figures show that six balances of the best make observed by three people at two different places gave a variation over as short a period as four months varying from 0.4 to 1.6 milligrams and that these variations cannot be correlated with any variation of external conditions. The author is well acquainted with earlier work by Poynting and others and does not doubt that accurate readings can be made over a short period but finds that constancy cannot be relied on over as short a period as four months. The natural suggestion of the cause of discrepancy is that there is a difference of temperature between the two arms of the beam.This has been dispelled by direct observation. Two thermometers reading to Os0lo were placed one on each pan of a balance in the same room as that containing the three balances used in London. Except in one instance when by accident direct sunlight fell on the bulb of one thermometer no greater difference than 0'02O was observed. Calculations confirming those of Landolt show that such a difference of temperature in the beam itself is negligible in its effect on the indications of the balance and this difference, which represents that of the pans is far greater than would be possible in a solid piece of metal like a beam under normal condi-tions. As the fact remains that these variations occur however, there clearly must be a. physical cause. The matter has been ref erred to engineers of eminence accustomed to consider stresses, and one was so good as to compute the stresses in a beam identical with that of two of the balances.He reported that the beam was amply strong to carry a load without flexure although condemning the design as clumsy. The slow flow of metals under stress is well known and might provide an explanation were it. not that th FRANCIS 3 4-DI-$I-NITROTETRAPHENYLFURAN. 1039 beam of a balance is not under stress except in the short time of weighing. Moreover sonie permanent set in one direction or the other might be expected. It remains to consider other probable causes of the inconstancy observed. There may be an alteration in the effective length of the two arms of the balance. I n the case of the six balances examined two had their end knife-edges set in sealing-wax two were held by set screws and the other two were apparently pressed in. I n all three methods of construction fortuitous movenient of the knif e-edge is easily conceivable and to this explanation the author inclines, As a balance of the best make is generally regarded as capable of use to its assigned limit of accuracy chemists generally have accepted its indications without quostioii. The present inquiry, which only arose out of the main research shows that this view is untenable if constant readings are to be expected over a relatively short time. Nor is there any indication as t o when the variations may occur. As many cheiiiical and physical experiments are neces-sarily lengthy an unsuspected alteration of the indications of the balance may in the past have led to grave errors. It seems to be incumbent on balance makers .to provide an instrument capable of carrying 200 grams in each pan turning with certainty t.0 0.1 milli-gram and dependable in this respect for a reasonable time-say a yea:-without alteration or readjustment it being always under-stood that all proper care is taken in using the instrument. A t tho time of writing i t appears that such a balance does not exist. 76 YORK ST., WESTMINSTER. 8. W. LReceived October 25&h 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101035

出版商:RSC    

年代:1917

数据来源: RSC

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FRANCIS 3 4-DI-P-NITROTETRAPHENYLFURAN. 1039 XCI .-3 4-Di-p-nitrotetrtxphen?/lfuran. By ARTHUR GORDON FRANCIS. THE formatioil of furan derivatives by the condensation of benzoins has been observed by several workers. Zinin ( Z e i t s c h . fiir Chemie, 1867 [ii] 3 313) by the action of concentrated hydrochloric acid a t 130° on benzoin obtained lepiden benzil and an oil. Limpricht and Schwanert (Ber. 1871 4 337) showed that dibenzoylstilbene (Zinin’s acicular oxylepiden) is obtained by digesting benzoin with dilute sulphuric acid and that when heated with benzoin i t yields lepiden aiid benzil. On reduction dibenzoylstilbene yields bidesyl 1040 FRANCIS 3 ~-DI-~~-NITROTETRAPHENYIAFURAN. Magnanini and Angeli (Ber. 1889 22 855) showed that when bidesyl is heated with concentrated Iiydrochloric acid a t 130-140° for two hours lepiden is formed.Dorn (Annalen, 1870 153 358) suggested and Japp and Klingemann (T. 1890 57 662) showed, that lepiden is tetraphenylfuran. Japp and Tingle (T. 1897 71, 11 38) proposed the formula : C Ph===CP h for dibenzoylstilbene . The relation of these compounds is shown in the following scheine : Benzoin. Bidesyl. Dibenzoylstibene. CPh===CPh I QHPh*OH YH Ph H Ph COPh COPh c0Ph m<O,>b€% \x lHC1 ../ 9 Yh-SPh CPh CPh \/ 0 Lepiden or tetraphenylfuran. More recently Irvine and McNicoll (T. 1908 93 950 1601) have shown that methoxyfuran derivatives can be obtained by the action of hydrochloric acid in methyl-alcoholic solution on benzoin, aiiisoin and furoin but that when ethyl alcohol is substituted for methyl alcohol no such condensation products are formed only the ethyl ester being obtlained as is usual in the Fischer esterification process.The author and Keane (T. 1911 99 344) described pnitro-acetylbenzoiii and attempted to hydrolyse this substance and also the nitrobenzoylbenzoin prepared by Zinin (Annalen 1857 104, 116). Zinin states that the position of the nitro-group in nitro-benzoylbenzoin was not determined. This compound is now shown t o be p-nitrobenzoylbenzoin NO,*C,H,*CHBz*OBz by the same methods that fixed a similar constitution for p-nitroacetylbenzoin Both p-nitroacetylbenzoin and pnitrobenzoylbenzoin yield on hydrolysis with hydrochloric acid under appropriate conditions the same condensation product together with p-nitrobenzil.The reac-tion is quantitative and f o r every three molecules of nitroacyl-(ZOC. cit.) FRANCIS 3 4-DI-p-XITROTETRAPHENYLFURAN. 1041 benzoin used one molecule of the condensation product and one molecule of p-nitrobenzil are formed. This condensation product is shown to be 3 4-di-p-nitrotetm~pheizyZf zcmn. The probable course of the reaction may be stated as follows: (1) The nitroacylbenzoin is first! hydrolysed : NO,*C,€I,*CHBz*OBz(Ac) -+ NOz*C,H,*CHBz*OH. (1.) (2) Two molecules of the nitrobenzoin thus formed are condensed and reduced to dinitrobidesyl by a third molecule of nitrobenzoin, which is itself oxidised t o p-nitrobenzil : NO2*C6H;CHBz*0H NO C,H C H Bz *OH HO*CH Bz.C,H;NO, N0,*C6H4*CH Bz*CHBz*C,H,*NO2 + N O,*C H4*CO13z (11.) (3) The dinit,robidesyl under the influence of hydrochloric acid loses water and is converted into dinitrotetraphenylfuran : N02*COH4* $!H-$!H *C,H; NO, N 0,- C,N,* E-- y*C,H **NO, + COP11 COPh CPh*OH CPh-OH -+ CPh CPh NO,* C H g-g* C,H N 0, \/ 0 From this view of the course of the reaction the constitution of the condensation product is regarded as 3 4-di-p-nitrotetraphenyl-furan.The intermediate compounds pnitrobenzoin (I) and dinitro-bidesyl (11) have not as yet been obtained although attempts were made t o isolate them by partial hydrolysis by means of hydrochloric acid and water. The investigation is accordingly incomplete in this respect but the results obtained so far are published as the author is likely t o be prevented by pressure of other work from continuiug the research for some time to come.E X P E R I M E N T A L . Hgdrolysis of p-Nit roace t yl b en aoi n . Forty grzms of p-nitroacetylbenzoin melting a t 1 2 5 O (uncorr. ) were dissolved in 500 C.C. of boiling 90 per cent. alcohol in a capa-cious flask fitted with a reflux condenser. When completely dis 1042 FRANCIS 3 4-DI-$l-NITROTETRAPHENYLFURAN. solved 30 C.C. of concentrated hydrochloric acid (D 1.16) were added slowly through the condenser so as not to stop the ebullition of the liquid. At the end of half an hour yellow needles began to be deposited. After six hours a voluminous mass of crystals had separated and the solution had a strong odour of ethyl acetate. It was then filtered while boiling and washed several times with boiling 90 per cent.alcohol to remove 2)-nitrobenzil. The crude product melted a t 207O (uncorr.) and after recrystallisation from glacial acetic acid the pure substance (21 grams) melted a t 2 1 1 O (uncorr.). From the alcoholic solution 10 grams of pnitrobenzil were reccwered. 3 4- D~-pnitrotetraphenyZfuran crystallises from glacial acetic acid in long pale yellow silky needles. It is very sparingly soluble in light petroleum ether cold or hot 90 per cent. alcohol or water, and moderately so in benzene toluene acetone or chloroform. It crystallises best from acetic anhydride or glacial acetic acid. One gram dissolves in 50 C.C. of boiling glacial acetic acid : 0.1002 gave 0.2672 CO and 0.0357 H,O. C= 72-72; H=3-95. 0.2744 , 15.0 C.C.N (moist) a t 1 9 O and 748.5 mm. N=6*28. 0.3384 in 17.677 benzene gave E =0*12O. C,,H,,0,N2 requires C = 72.73 ; H = 3.90 ; N = 6.06 per cent. M.W =462. M.W. =426. A c t i m of Alcoholic Hydrogen Chloride a t 42O on p-Nitroacetyl-benzoin. Two granis of pnitroacetylbenzoin were heated with 150 C.C. of absolute alcohol saturated with dry hydrogen chloride in a thermo-stat a t 42O for four hours. After some time a yellow solid sepa-rated which on crystallisation from glacial acetic acid melted a t 21 Oo and was dinitrotetraphenylfuran. From the portion soluble in alcohol only p-nitrobenzil melting at 140° could be isolated together with unchanged nitroacetyl-benzoin. Action of Wccter on p-Nitroncetylbenzoin. Five grams of nitroacetylbeiizoin were heated with 10 C.C.of water a t 180° for six hours. No pressure was observed on opening the tube. The aqueous layer was decanted through a filter and was found t o contain acetic acid. The solid product was a red resin, from which 23-nitrobenzil melting a t 140° and p-nitrobenzoic acid melting a t 238O were isolated. No dinitrotetraplienylfuran was iso-lated nor could any intermediate product be obtained PRANCIS 3 4-DI-~-NITROTETRAPHEXYLFURAN. 1043 Coiistit rhon of Nitroben zoylb eiazoin X’itrobenzoylbenzoin was prepared by Zinin’s method (loc. c i t . ) . The specimen melted a t 1 3 7 O (uncorr.). (Found N=4*3. Calc., S =3*9 per cent.) When hydrolysed and oxidised by nitric acid (D 1.4) i t yields benzoic acid and p-nitrobenzil. When oxidised with a mixture of suiphuric acid (20 C.C.of concentrated sulpliuric acid in 20 C.C. of water) and ar approximately normal solution of potassium dichromate as described for pnitroacetylbenzoin (Zoc. c i t . ) i t yields benzoic acid and p-nitrobenzoic acid. The constitution, (4)N02-C,H,( l)*CHBz*OBz, similar to that of pnitroacetylbenzoin is therefore deduced.. These reactions take place with more difficulty than in the case of pnitro-acetplbenzoin. Hydrolysis o f p-Nitro b enzoyl h e n zoin. (1) Five grams of p-nitrobenzoylbenzoin melting a t 1 3 7 O were heated under reflux with 150 C.C. of ethyl alcohol and 7 C.C. of aqueous hydrochloric acid (D 1.16). A t the end of two and a-half hours there was no separation of yellow needles no yellow colour in &he solution and no d o u r of ethyl benzoate. The p-nitrobenzoyl-bezoiii was recovered unchanged. (2) Four grams of pnitrobenzoylbenzoin were heated under reflux for twenty-four hours with a mixture of equal parts of aqueous hydrochloric acid (D 1.16) and ainyl alcohol more acid being added from time t o time. The insoluble product weighed 2.2 grams. After crystallisation once from toluene and twice from glacial acetic acid there remained 1.5 grams of dinitrotetraphenyl-f waii melting a t 2 1 0 O . When mixed with dinitrotetraphenylfui-an irielting a t 21 lo obtained by the hydrolysis of pnitroacetylbenzoin, the mixture melted a t 2 1 0 O . The substances were therefore iden-tical. CHEXICAL DEPARTMENT, SIR JOHN CASS TECHNICAL INSTITUTE, Loxno~ E.C. [Rereivecl September 7th 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101039

出版商:RSC    

年代:1917

数据来源: RSC

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1044 MASON AND WHEELER THE " UNIFORM MOVBMENT " XCII.-The " Uniform Movement '? during the P~opayation of Flame?. By WALTER MASON and RICHARD VERNON WHEELER. THE initial slow propagation of flame that takes place when an inflammable mixture a t rest is ignited at a point is usually re-garded as controlled by the transference by conduction of the heat developed by the combustion of the mixture immediately surround-ing the point of ignition whereby successive contiguous portions of the mixture are raised in temperature until chemical action becomes rapid. The initial speed of propagation of flame in a given mixture away from the point of ignition should mainly depend according to this view (1) on the conductivity for heat of the unburnt mis-ture and (2) on the velocity with which a moderately heated layer begins to react chemically and so to rise gradually in temperature, or in other words on the rate of change of reaction velocity with temperature.Under certain conditions with all inflainniable mixtures of gases and air a t atmospheric temperature and pressure the initial slow propagation of flame can be maintained at a uniform speed over a considerable distance of travel from the point of ignition. The con-ditions most favourable o r necessary to obtain and maintain this '' uniform movement " of flame are that the inflammable mixture should be contained in a long straight and horizontal tube open a t one end and closed a t thehother; and that ignition should be effected a t the open end of the tube by a source of heat not greatly exceeding in temperature the ignition-temperature of the mixture, and not productive of mechanical disturbance of the mixture.The speed oaf the uniform movement then depends on the compositjon of the mixture (presumed to be a t atmospheric temperature and pressure) and on the diameter of the tube in which it is contained (see p. 1051); above a certain (sinall) diameter the material of which the tube is made does not appreciably affect the speed of the flame. With a tube of given diameter the speed of the uniform movement of flame in a mixture can be regarded as a definite physi-cal constant for that mixture. Following Vicaire (Ann. Chhn. Phys. 1870 [iv] 19 118) Mal-lard and Le Cliatelier (tlnn. des Mines 1883 [viii] 4 274) Put forward theoretical considerations respecting the transference of heat during the burning of gaseous mixtures from which i t should be possible to deduce the speed of the flame during the uniform movement as follows DURING THE PROPAGATION OF BLAME.1045 Suppose the flame to be propagated in a tube of uniform cross-section filled with the combustible mixture a t an initial tempera-ture 8. At a given moment during the propagation the “layer,” A (Fig. l) becomes inflamed. The mass of burnt gases which fills the tube behind ,4 is a t a temperature T the “ combustion-tempera-ture,” which can be calculated. The layer of gas immediately in contact with A and in front of i t is a t the ignition-temperature t , of the mixture or rather a t a temperature infinitely close t o t. The successive layers in front are a t temperatures gradually decreas-ing froin t to 6.The layer A itself must be a t a temperature T;, higher than T f o r a t the moineiit when i t was inflamed it had already been raised t o t . If we neglect t.he variation in the specific FIG. 1. T’ heats of the gases between T I‘i=T+ t . +--and TI and assume 8=0 then A t the moment of inflammation of the layer A of thickness ds, the distribution of temperatures in the tube can be represented as in Fig. 1 in which beyond d a gradual levelling of temperature froin Y’I t o T is shown. At the end of an infinitely short time d7, the layer A’ of thickness ds next to the layer A becomes inflamed in its turn and the whole diagram advances through a distance ds. For this to take place the front part of the tube must gain a quan-tity of heat represented by the infinitely small area tt‘88‘ which is equal to the rectangle AA’tt’.This quantity of heat is t h a t neces-sary to raise the temperature of the layer of thickness ds from 8 t 1046 MASON AND WHEELEE THE “ UNIFORM MOVEMENT ’’ t ; it is therefore equal t o cl(t-O)ds c’ being the specific heat of the burning or just burnt gases. The quantity of heat lost by the hinder part of the tube must balance that gained by the front part. Now the layer A that gives up its heat in front is a t a temperature TI. and is between a layer a t a temperature t and one a t T. Tlie quantity of heat given u p by A in unit time will therefore be a function of T and t and can be stated thus: d ( t - d)d.s=drF(T,t), whence we obtain for the speed of propagation of flame: v=~’S/ds=F(T,t)/cl(t-d) .. . . (1). The exact form of the function F ( T t ) cannot readily be deter-mined. However one can presume that it is proportional to the conductibility L of the unburnt gas; and one can state that it beconies zero when T = t and for that value of T only. It would seem that when the temperature of combustion T exceeds the temperature of inflammation t the heat necessary for the inflam-mation of a layer can be transmitted integrally. We can therefore put the expression for ‘I! in the forin: . (2) and i t may be that F ( T t ) is a constant. The only point open t o criticism in this otherwise lucid reasoning is t h a t which attributes t o the “layer” of gas that is actually burning a higher temperature (TI) than i t would attain if it biirned without previous heating to its ignition-temperature ( t ) .Mallard and Le Chatelier found confirmation of this view in the observation by Gouy (,4nn. Chim. Pl~ys. 1879 [v] 18 1) t.hat as judged from photometric measurements the surface of the bright green inner cone of a Bunsen flame is the hottest part of the flame; f o r the surface of this inner cone is the ‘‘ burning layer ” of a stationary explosion the rate of propagation of flame downwards in the mix-ture being equal to the rate of flow or^ the unburnt gases upwards. Gouy showed t h a t there is a simple relation between the area of surface of the inner cone the rate of flow of the mixture and th9 s p e d of propagation of flame therein; and llichelson (Ann,.Phys. Chem. 1889 [iii] 37 l ) who adopted in toto Mallard and Ide Chatelier’s theoretical considerations and a t a later date Mache ( A n n . Physik. 1907 [iv] 24 527) used this relation t o determine the “normal” speed of propagation of flame in a number of gaseous mixtures. Haber and Richardt (Zeitsch. mtorg. Chem. 1904 38 5) how-ever showed by actual thermo-electrical measurements that th DURING THE PROPAGATION OF FLAME. 1047 surface of the inner cone of a Bunsen flame is not the hottest part of the flame and concluded that its brightness is a phenomenon of luminescence. Further they denied tlie possibility of the burniiiq layer during the uniform movement in the propagation of flame along a tube attaining a higher temperature than i t would if i t were heated merely by its own heat of radiation f o r the reason that while i t is burning i t must lose to successive layers as much heat as it gained from earlier burnt layers.Haber and Richardt’:, argument is siirnmarised in the following quotation from their paper (p. 55) : ‘‘ Die Vorwarmung eines esplosibleii Gasgemenges erhiil t die Verbrennungstemperatur wenn sie auf Kosten dar Warnle des rerbrannten Gases erfolgt (Regenerativsystenl ()fen der Gasan-stalten u.s.w.) aber sie erholt sie nicht wenii sie auf Kosteri der Warme des verbrennenden Gases erfolgte (Flamme Explosion) tleiin da das Gebilde welches die Vorwarmung bewirkt soviel Wiirme abgibt als das vorgewarmte aufnimmt so kanii Temperatur-steigeruiig durch Vorwarmung nur eintreten wenn die Tf’arme-abgabe dem Temperaturansteig zeitlich nachfolgt und nicht..wen?^ sio ihn begleitet.” We consider Haber and Richardt’s view to be the correct one. Mallard and Le Chstelier’s equation (2) is however affected only as regards the magnitude of the function P(T,t) which is in any event indeterminate. The important deduction from the equ a -tion is that in mixtures t h a t have the same conductibility for heat, the speed of the fleme during the uniform movement should Iw directly proportional t o T - 2 and inversely proportional to f - H . The effect of variation in the conductibility of the mixture 011 the speed of the uniform movement of flame is well shown with mixtures of hydrogen and air (Haward and Otagawa T. 1916, 109 85).The fastest speeds are obtained with mixtures contain-ing from 38 t o 45 per cent. of hydrogen instead of with the mixture that contains hydrogen and oxygen in combining proportions anti has the highest temperature of combustion. The thermal conduc-tivity of hydrogen is 31.9 x 10-5 compared with that of air, 5-22 x 10-5 and as zlready stated the mixtures in which the speeds of the flames are fastest contain between one-third and one-half their volume of hydrogen. When the combustible gas has a thermal conductivity more nearly approaching that of the air with which i t is mixed and when it forms but a small proportion of t h e mixture as with methane the influence of thermal conductivity on tho speed of propagation of flame can be neglected o r regarded a s constant.If c’ also be regarded as constant over the range of temperature 1048 MASON AND WHEELER THE (' UNIFORM MOVEMENT " concerned the speed of the uniform movement of flame in mixtures such as those of methane with air should be proportional t o T - t / t - 8 if the uniform movement truly represents the transfer-ence of heat by conduction. I n order t o obtain data whereby t o k t this conclusion and t o elucidate the nature of the physical constant which we regard the uniform movement of flame t o be, we have determined the speeds (in a tube 5 cm. in diameter) in a number of mixtures of methane oxygen and nitrogen of which we have also determined the relative ignition-temperatures and of FIQ. 2. which the theoretical combustion-temperatures have been calcu-lated.The results are shown in Fig. 2 which apart from the problem with which we are now concerned is of interest in showing the effect of reducing the oxygen coiitent of the air on its ability t o support the combustion of methane. I n the topmost curve the speeds of the flames are plotted against percentages of methane in atmospheric air *; the curve below was obtained with an " atmo-* This curve which is reproduced also in Fig. 3 is constructed from the figures given by Wheeler (T. 1914. 105 2606) after applying a correctio DURING THE PROPAGATION OF FLAME. 1049 sphere” containing 20.60 per cent. of oxygen; then follow in suc-cession curves obtained with atmospheres containing 18.85 17.60, and 15-05 per cent. of oxygen respectively the percentages of methane in each instance being percentages in the particular ‘‘ atmosphere.’’ (For example the 7 per cent. methane mixture with the 15.05 per cent. oxygen “atmosphere” had the followixig composition methane 7.0 ; oxygen 14.0 ; nitrogen 79.0 per cent .) It will be seen t h a t the speeds of all the limit mixtures (in which a balance is struck between tlie heat generated on combustion and the heat required to start combustion) are the same. The calcu-lated ratios T - t / t - 8 for each limit mixture are however not the same being greater by about 50 per cent. for the higher limit mix-tures than for the lower. Calculation of the theoretical combustion-temperatures of the mixtures is comparatively simple so long as they contain sufficient oxygen to burn tlie methane completely.When the-oxygen is in defect it is necessary to take into account the mechanism of com-bustion of methane. This in accordance with Eone’s researches on the slow combustion of methane and as Burgess and Wheeler found in their experiments with ‘‘ limit ” mixtures of methane, oxygen and nitrogen (T. 1914 105 2596) involves as the reac-tion essential to the propagation of flame the formation of carbon monoxide hydrogen and steam in equal volumes according to the scheme : (CH,O) CH,+O = CO+H,+H,O. Following upon this reaction the carbon monoxide and hydrogen are burned practically completely to carbon dioxide and steam if the ratio O,/CH is 2.0 or greater; or if the ratio is less than 2.0, proportionally to the oxygen-concentration.Analyses of samples of the burnt gases taken during the propagation of flame before their cooling enabled the ‘‘ water-gas reaction ” to come into play, showed that with the mixture containing the lowest ratio O,/CH, (namely 1.20 for the higher limit mixture with air),. the propor-tion of the methane burned completely t o carbon dioxide and steam was nearly 33 per cent. ; whilst the proportion so burned increased regularly with the ratio O,/CH to just over 99 per cent. for mix-tures with a ratio 2.0. t,hat w~ls found to be necessary by reason of the fact that the “ standard ” $-seconds clock used for the determinations recorded 50 seconds per minute instead of 60. The speeds given in Wheeler’s paper although relatively correct (the paper dealt only with the relrct]ive speeds) are therefore too high by one-sixth 1050 MASON AND WHEELER THE “ UNIFORM MOVEMENT ” The1 relative ignition-temperatures of the mixtures were deter-mined in a manner which will be described in a subsequent paper.It warp found that over the range of mixtures covered by the experi-ments EOW described there was a nearly regular increase in the ignition-tempeKature as the’ ratio O,/ CH decreased. The relative ignition-temperatures can be regarded as ranging from 650° for a mixture containing 5.5 per cent. of methane in air to 700° for one containing 14.5 per cent. When the ratios T - t / t - 8 for all t,he mixtures comprised within the curves shown in Fig. 2 are calculated i t is found that Mallard arid Le Chatelier’s equation (2) holds very closely so long as the oxygen in the mixtures is in excess; that is t o say so long as it is possible for the comb us ti or^ of the methane to be carried rapidly t o completion When the combustion is incomplete however the ratio T - t l t - 6 is in general higher than t,he speed of t h e i i n i -form movemelnt of flame in the niixture requires.It becomes as alrea,dy stated markedly high for the upper limit mixtures. The natural inference to be drawii from this result is that there is an enhanced radiation loss through the walls of the tube during the propagation of flame in mixtures containing excess of methane, presumably because the process of combustion of such of the methane as burns is more protracted than when excess of oxygen is present and the reacting molecules remain €or a longer time in a condition of vibration such a s to enable them to emit radiations.This presumed protraction of the process of combustion (of which a long luminous tail behind the flame-front in mixtures containing excess of methane is perhaps evidence) would prevent the atkain-ment of the calculated ‘‘ combustion-temperature.” It is in fact, evident from these experiments that little meaning attaches to the usual calculations of combustion- or flametemperatures if only for the reaqon that the effect of the 10% of energy by radiation and the variations in that loss dependent on the duration of chemicaI change during combustion are not taken into account. , The Infithence of the Diameter of the Tube o n the Speed of t h e Uniform Movement of Flame in Mixtures of Methane and Air.According to Mallard and Le Chatelier cooling of the hot gases by the walls of the tube does not appreciably affect the speed of the flame when the diameter is sufficiently great for the following reasons The quantity of heat withdrawn from the burning gases by the walls of the tube is proportional to the perimeter 2 r r of the tube; to the difference between the temperature of the gases and that of the tube T - 8 ; and to a coefficient of conductibility k DURING THE PROPAGATION OR' FLAME. 1051 The mass of the burnt gases is proportional to r2 and to the speed of propagation of the flame u; so that if Q be the heat of com-bustion and c the specific heat of the burnt gases, Qr%= c & I ( T - 8 ) + kr(T - O ) , whence T = 8 + & / ( c + k / r v ) .The temperature T will not be materi-ally affected when k / r v is negligible compared with c ; that is to say when T and u are sufficiently great. For their experiments with mixtures of methane and air Mallard and Le Chatelier used glass tubes 5 cm. in diameter which they considered to be sufficiently large to overcome the effects of cooling by the walls even with the most slowly moving flames. This we believe to be correct for there is not much difference in speed in tubes from 5 to 10 cm. in diameter whereas when the diameter of the tube is only 2.5 cm. the speed is reduced by about onethird. Cooling by the walls thus interferes with the measurement of the true speed of the uniform movement of flame in mixtures of methane and air unless the diameter of the tube exceeds about 5 cm.When however the diameter is increased above 10 cm. the speed of the flames is affected by the coming into play of another factor namely convection. The influence of convection currents is noticeable with the fastest moving flames in tubes 10 cm. in diameter the visible effect being a turbulence of the flame-front. So far as can be judged by eye, the turbulence is essentially a swirling motion in a direction nearly normal to the direction of translation of the flamefront which as in tubes of smaller diameter progresses a t a uniform speed for about 150 cm. before backward and forward vibrations (the " vibratory movement ") are set up. This swirling motion appears ab initio and is due to rapid movement of the hot gases from below upwards by convection.I n tubes of comparatively small diameter (5 t o 9 cm.) this rapid movement is suppressed although the shape of the flame-front shows that there is a definite movement of the hottest gases towards the upper part of the tube (see T., 1914 105 2609). We have determined the initial uniform speeds of the flames over the whole range of inflammable mixtures of methane and air in tubes 2.5 5 9 30.5 and 96.5 cm. in diameter. The results are shofn graphically in Fig. 3 in which the speeds of the flames are plotted against percentages of methane in air. If for any given mixture say 10 per cent. methane the speed of the flame is plotted against the diameter of the tube in which it travels a curve such as those shown in Fig.4 is obtained. From these curves it is clear that in tubes of less than 5 cm. diameter the speed of the flame is V O L 0x1. T 1052 MASON AND WHEELER THE “ UNIFORM MOVEMENT ” retarded by the cooling effect of the walls. I n tubes of large diameter however from 10 cm. upwards the speed of the flame is proportional t o the diameter of the tube. The “uniform movement” of flame as defined by Mallard and Le Chatelier (that is I ‘ le mode de propagation par conductibilit6 ”) is thus a strictly limited phenomenon obtainable onlv in tubes J FIG. 3. * 1 12 13 1 Methane. Per cent. in air. within a certain range of diameter large enough to prevent appreciable cooling by the walls but narrow enough to suppress the influence of convection currents.The initial speed of flame in mixtures of methane and air is uniform also in tubes of large diameter-the flames travelled a t a sensibly uniform speed over a distance of 10 metres in a tube 96.5 cm. in diameter and 44 metres long-but as we have shown this uniform movement does no DURING THE PROPAGATION OF FLAME. 1053 result from the normal transference of heat from layer t o layer of the mixture by conduction. When speaking of the uniform movement of flame in gaseous mixtures it is necessary therefore if Mallard and Le Chatelier’s definition be accepted t o specify the diameter of the tube in which the mixtures were contained. Alternatively the initial slow uniform movement can be regarded simply as a particular phase in the propagation of flame t h a t results tvlien ignition is effected (in a quiescent mixture) a t the open end of a straight horizontal tube of any diameter closed a t the other end; and not as resulting from a particular mode of heat transference.Fxa. 4. 0 Diameter of tube in cm. C3 E x P E R I M E N T A L. The method of recording the speed of the flames and the general mode of procedure for the experiments in glass tubes have been described by Wheeler (Zoc. c i t . p. 2610). The method was essenti-ally that of registering 011 a chronograph the times a t which fine screen-wirm of copper (0.025 mrn. in diameter) through which an electric current was passing were fused as the flame reached them. We may add to the description already given the detail that the electric current passing through the screen-wires was sufficient t o raise them nearly to red heat.This arrangement ensured the T T 1064 MASON AND WHEELER THE '' UNIFORM MOVEMENT " rapid melting of the wires as soon as the flame touched them and therefore gave very uniform results; wires made from metals or alloys of low melting point which could not be drawn so fine or of so uniform a diameter as copper were found to be unsatis-factory. For the experiments in the larger tubes (30.5 and 96.5 cm. iii diameter respectively) which were of mild steel the screen-wires were mounted on supports of brass wire reaching nearly to the horizontal axes of the tubes and fixed through screwed-in plugs of vulcanite 50 cm. apart along the length of each the first screen-wire being 50 cm.from the point of ignition. It' was filled with the required mixture which had previously been pre-pared in a gas-holder of 42.48 cubic metres capacity by displace-ment of air six times the volume of the tube being taken for dis-placement. Samples of the mixture for analysis were taken from the gas-holder and from near the open end of the tube just before ignition. The tube of 96.5 cm. diameter was 44.25 metres long and was provided with a by-pass tube 15-24 cm. in diameter running its whole length and fitted a t either end with valves which were closed during an experiment. A motor-driven fan was included in this by-pass connexion and served to circulate the contents of both tube and by-pass when making the mixture of methane and air required for an experiment.The mixtures were made by passing into the tube a measured quantity of methane from a storage holder displacing an equal quantity of air an3 circulating the contents as aforesaid during two hours the end of the tube a t which the mixture was t o be ignited being temporarily closed during this operation by a gas-tight cover of wood. Samples of the mixture for analysis were taken from both ends of the tube before each experiment ; no appreciable difference was found between the compositions of samples of the mixture at either elid of the tube. For all the experiments including those in the glass tubes the methane used was from a blower of firedamp in South Wales, whence it was obtained compressed in cylinders. It contained no appreciable impurity other than between 2 and 24 per cent.of nitrogen . The tube of 30.5 cm. diameter was 15-24 metres long. The analyses always closely agreed. In the opening paragraphs of this paper we indicated some of the conditions necessary t o ensure the obtaining of the uniform iiiovement of flame. One of the essential conditions is that igni-tion should be effected at or within 3 OT 4 on. of the open end o DURING THE PROPAGATION OF FLAME. 1055 the tube. This is particularly necessary with narrow tubes other-wise if the point of ignition be some considerable distance within the tube flame travels in both directions from the point of ignition, and the disturbance caused by the flame travelling towards the open end affects the flame travelling towards the closed end. The result is that a vibratory motion is imparted at the outset to the flame and records of the speed of the flame travelling towards the closed end show in consequence wide variations from one experi-ment to another with the same mixture.F o r example the following records were made of the speed of flame in a mixt>ure of methane and air con€aining 10.00 per cent. of methane. A tube 5 cm. in diameter and 5.2 metres long was used. I n one series of experiments the point of ignition was 4 cm. from the open end of the tube and in another it was 17 cm. The speeds were measured between t.wo screen-wires 50 cni. apart the first screen being 40 cm. from the point of ignition. Ignition was by a secondary discharge across a 3 mm. spark-gap using a “4-inch” induction coil with a current of 2.5 amperes through the primary circuit, Speed of ‘‘ Uniform Movement.” Cm.per second. Point of ignition 4 cm. from open end. 1 .................. 93.3 2 .................. 91.7 *> .................. 93.3 4 .................. 94. I 5 .................. 94. I 6 .................. 93.3 7 .................. 91-7 8 .................. 91.0 9 .................. 94.1 Mean ............ 92.9 Variation ...... -t 1.2 - 1.9 0 Point of ignition 17 cm. from open end. 88.0 91.3 88.8 87-2 80.9 00.3 94.5 83.3 86.2 87.8 + 6.7 - 6.9 Similarly with a glass tube 2.5 cm. in diameter when ignition of a mixture of methane and air containing 10.25 per cent. of niehhaiie was effected a t a point. 15 cm. from the open end vibra-tions were set up immediately in the flame travelling towards the closed end and wide variations were obtained in the records of speeds as follows 1056 MASON AND WHEELER ‘‘ UNIFORM MOVEMENT,” ETC.Speed of ‘( Uniform Movenient.” Cm. per second. Point of Point of ignition 4 cm. from open end. 1 65.5 59.1 2 6.5.5 50.0 3 66.2 52.5 4 65.5 57.0 ignition 15 cm. from open end. .................. .................. .................. .................. Mean ............ 65.7 Variation ...... -t 0.5 - 0.2 54.6 f 4 . 5 - 4.6 Apart from the wide variations in the recorded speeds when the point of ignition is too far within the tube it will be seen that the mean of the results shows a slower speed than when the point of ignition is properly placed.The reason for this is that the flame that travels towards the open end acts as a drag on the flame travelling towards the closed end. I n general unless care be taken t o avoid causing disturbance of the mixture a t the moment of ignition the records of speeds of flames obtained are of doubtful value. Another matter that requires attention is the possibility of any additional impetus given to the flame by the source of heat used to cause ignition affecting the recorded speed. This can be avoided by allowing the flame to travel a distance of 30 or 40 cm. before reaching the first screen-wire (see T. 1914 ,105 2610). When this precaution is taken the intensity and size of the source of heat used to ignite the mixtures can be varied considerably without affecting the measuremenk of the speeds of the flames as the following experiments illustrate.A glass tube 2.5 em. in diameter and 5 metres long was used, and the speed of the uniform movement of flame determined in a series of mixtures of methane and air. The mixtures were ignited by (i) secondary discharge sparks from an ‘(8-inch” X-ray coil with a current of 5 amperes through the primary circuit; (ii) secondary discharge sparks from a ‘( 4-inch ’) coil with a current of 2.5 amperes through the primary circuit; and (iii) the flame of a taper. The point of ignition was 4 cm. from the open end of the tube when sparks were used; a t the open end when the taper-flame was employcd. Tlie first screen-wire was 40 cni. from the open end of the tube THE HYDROLYSIS OF SODIUM CYANIDE. 1057 Speed of Met ham. Per cent. 7.10 7.80 23-05 8.60 9.10 9.50 9.95 10.25 10.55 11.60 12-25 Uniform Movement.” Cm. per second. Ignition by “ 8-inch ” coil. 37.0 47.0 51.0 57.3 64.6 66.6 66-2 65.5 61.0 46.7 35.0 Ignition by Ignition by &inch ” coil. taper. 37.3 36-6 47.7 47.5 52-5 52.1 58.0 58.7 64.0 64.4 68.3 66.6 67.8 65.5 65.5 66.2 61.8 61.5 47-5 47.9 35.1 35.0 It will be seen that for any of the mixtures the recorded speeds did not show any abnormal variations traceable to the means of of ignition employed. [Received October lDth 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101044

出版商:RSC    

年代:1917

数据来源: RSC

摘要:

THE HYDROLYSIS OF SODIUM CYANIDE. 1057 XCIII.-The Hydrolysis of Sodium Cyanide. By FREDERICK PALLISER WORLEY and VERE ROCHELLE BROWNE. IN the extraction of gold by the cyanide process the degree of hydrolysis of the sodium cyanide a t the dilution employed is con-siderable and any investigation of the chemical actions which occur in this process involves an accurate knowledge of the degree of hydrolysis of the cyanide in solutions of different concentra-tions. I n an investigation of the chemical actions occurring in the dissolution of gold by solutions of sodium cyanide the results of which will be published in a subsequent pap”’ it has been shown that the degree of hydrolysis of the cyanide is a most important factor in the rate of dissolution of the gold. The present paper deals with the degree of hydrolysis of sodium cyanide in solutions of widely different concentrations a t tempera-tures from Oo t o 30°.The method employed is so simple that it would form a useful exercise for students of physical cheniistry. It consists in com-paring the concentrations of hydrogen cyanide vapour above solutions of sodium cyanide and of hydrocyanic acid by drawing the vapour through a solution containing 0.2 per cent. of picric acid and 2 per cent. of sodium carbonate. The intensity of the reddish-brown colour produced in the indicator solution varies VOL. 0x1. u 1058 WORLEY AND BROWNE : rapidly with the concentration of the hydrogen cyanide in the vapour and by comparing the colours produced when a stream of air passes through a series of solutions of sodium cyanide of one concentration alternating with solutions of hydrocyanic acid of different concentrations the &strength of hydrogen cyanide solu-tion can be found which has the same hydrogen cyanide vapour pressure as the sodium cyanide solution.E X P E R I M E N TAL. The sodium cyanide was freshly prepared and in order to ascertain that no appreciable amount of free sodium hydroxide was present a sample was dissolved in water and titrated for cyanide with a standard solution of silver nitrate and for alkali with standard hydrochloric acid using methyl-orange as indicator. The hydrocyanic acid was prepared immediately before us0 and FIG. 1. 9 i NkOH NCN Indicator --of the strength required by adding an equivalent amount of hydrochloric acid to a solution of sodium cyanide.I n each experiment t,wo concentrations of hydrocyanic acid were employed one of which had a higher hydrogen cyanide vapour pressure than the hydrocyanic acid solution .and the other a lower pressure. The solutions of cyanide and of hydrocyanic acid were contained in 300 C.C. flasks and the indicator solutions in test-tubes 10 C.C. of the indicator solutions being used and about 100 C.C. of the other solutions. The flasks and test-tubes were arranged as in Fig. 1 a test-tube containing sodium hydr-oxide solution being placed a t the beginning in order to remove carbon dioxide. I n a preliminary experiment, the diff ereiice in concentration between the two acid solutions was considerable thereby giving an indication of the approximate strength required in order t THE HYDROLYSIS OF SODIUM CYANIDE.1059 match the cyanide solution. In subsequent experiments the difference in concentration could be made very much smaller still allowing the intensity of colour produced by the cyanide to be intermediate between those produced by the two acid solutions or to coincide with one of them. Thus the concentration of hydrocyanic acid which had the same hydrogen cyanide pressure as the cyanide solution was determined within very narrow limits. Air was drawn through the flasks a t the rate of about one bubble per second. A t the higher temperatures the apparatus was kept in a constant-temperature air-chamber electrically heated and electric-ally controlled and a t the lower temperatures in water a t constant temperature or in melting ice.The temperatures employed were Oo 5O loo 1 5 O 20° 25 and 30°. Possible Sources of Error.-(l) By placing two indicator tubes together in series it was found that the whole of the hydrogen cyanide was absorbed in the first no perceptible change of colour being produced in the second. Thus one indicator tube after each flask was sufficient. (2) The amount of hydrogen cyanide removed from the solu-tion was found to be too small to affect the concentration or degree of hydrolysis of the solution. This was shown by measuring the degree of hydrolysis of the same solution of cyanide a second time, using fresh solutions of hydrocyanic acid the result in the second case being the same as in the first.(3) The possibility of error due ta the slight pressure gradient in the series of flasks was avoided by placing the cyanide solution between the two acid solutions. By reversing the order of the two acid solutions placing the stronger after the cyanide in one experiment' and before it in another (the same strength of solu-tion being used) no perceptible difference was observed showing that the slight pressure gradient was negligible. (4) I n order to ascertain whether the effect of the non-hydro lysed sodium cyanide on the vapour pressure of the free hydrogen cyanide was of importance experiments were carried out in which the hydi.ogen cyanide vapour pressure of hydrocyanic acid solu-tions containing sodium chloride was compared with that of solu-tions containing no salt.The presence of even large quantities of salt had no perceptible effect on the amount of hydrogen cyanide removed by the air and i t was consequently judged that the effect of the sodium cyanide was negligible. Results.-From the equation expressing the hydrolysis of sodium cyanide, NaCN + H,O NaOH + HCN, u u 1060 WORLEY AND BROWNE : it is obvious that in the presence of a large excess of water the relationship between the concentrations of the various compounds should be expressed by the mass-action equation “aOHICHCN1 _hT. LHCNI and also that this relationship should hold in the presence of excess of either sodium hydroxide or of hydrocyanic acid. I n the P I G . 2. Cube roots of concentrations. absence of excess of alkali or acid if C is the concentration of the total sodium cyanide and P the percentage hydrolysed then p2c - K.Experiments were carried out a t 2 5 O on the hydrolysis of sodium cyanide a t a number of concentrations from 5.2 t o 0.00725 gram-molecules per litre and a t a concentration of 0.0435 in the presence of different amounts of sodium hydroxide and of hydrochloric acid. I n the latter case it is obvious that an excess of hydro-cyaiiic acid equivalent to the hydrochloric acid was liberated. The results of these experiments are shown in tables I and 11. 100(100 - P THE HYDROLYSIS OF SODIUM CYANIDE. 106 1 Gram-mols. of NaCN per litre (C). 5-20 2.60 1.00 0-325 0.163 0.0813 0.0435 0.0290 0.0145 0.0073 TABLE I. Tcrnperature 2 5 O .Percentage hydrolysed P (PI* I< x lo4. (calculated). 0.30 0.47 0.303 0.425 0.48 0.429 0.70 0.49 0.692 1-25 0.50 1.21 1-75 0.49 1-70 2.5 0.50 2.40 3.3 0.49 3.27 4-0 0.48 3.99 5.5 0.47 5-59 7.75 0.47 7-82 Mean 0,484 TABLE 11. 0.0435 Gram-mols. of NaCN per litre NROH per gram - Percentage Gram-mols. of mol. of NaCN. hydrolysed. K X lo4. 1.00 0.11 0.48 0.50 0.223; 0.60 0.25 0.45 0.50 0.01 2.8 0-47 -Gram-mols. of HCI. per gram-innl. of NaCN. 0.4 40.175 0.49 0.3 30.25 0.47 0.2 20.45 0.48 0.1 10.9 0.47 -Mean 0.483 I n the last coluinn of table I is given the percentage of hydro-lysis calculated from the mean value of the constant. It is obvious that there is no perceptible variation in K beyond that due t o experimental error and thatt there is remarkably little difference between the degree of hydrolysis found by experiment and that calculated from the mean value of I .. I n Fig. 2 the curve expresses the calculated degrees of hydro-lysis and the circles the experimental. values the abscissze being the cube roots of the concentrations in order t o produce a flatter curve. The effect of temperature on the value of the constant was found from experiments carried out a t intervals of 5 O from Oo to 30°. Fewer concentrations were used than at 2 5 O a t some temperatures only one concentration being employed. The results are given in table 111 the relationsliip between the tempera 1062 THE HYDROLYSTS OF SODIUM CYANIDE. ture and the mean values of K being shown in the form of a curve in Fig. 3. TABLE 111. C. P. K x 104. (Mean) Temperature. 0" 0.550 0.50 0.14 0.135 - 0.0435 1.75 0.13 -5 0.550 0.53 0.15 0.15 10 0.550 0-54 0.16 0.16 11 0.550 0.60 0.20 0-20 20 0.325 0.27 -0.0435 0.28 0.0145 4.25 0.27 0.27 0.0036 8.0 0.25 - - - - 0.484 25 Table 1 -30 0.325 1.5 0-74 -0.0435 4.0 0.72 0-72 I 0.0145 6.75 0.71 -FIG. 3. -Temperature. From these results it is possible t o calculate the degree of hydrolysis of solutions of sodium cyanide of concentrations up to 5.2N a t any temperature between Oo and 35O. UNIVERSITY COLLEGE, AUCRLANn [Received September 26th 1917.

ISSN:0368-1645    

DOI:10.1039/CT9171101057

出版商:RSC    

年代:1917

数据来源: RSC