INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1947
TABLEIr. COMPARISOS O F BROWNIKGRATES CALCULATED FROM FIGURE 8 WITH OBSERVEDBROWSINGRATESFOR DRIED NONSULFITED IYHITE
POTATO
FROM
VARIOVS
PLASTS H20 sample so. 1
2
3
1
2
(hI.F.B.),
7%
6.5
7.6
7.9 6.5 7.6
3
7 9
1
4.6b 4.7b
2
3
Sugar a s Glucose (hl.F.B ), % Total Reducing
3.28 2.79 2.94
..
..
1.04 1.41 1.12
1299
and wise counsel of L. B. Howard, formerly clf this laboratory, and of J. R. RIatchett of thislaboratory.
COMAIERICAL LITERATURE CITED
storage Temp,
C. 38 38 38 49 49 49 49 49 49 49
Rates Calcd.
32 52
60
280 440 490 120 120 120 160
.Illen, R. J. L., Barker, J., and Mapson, L. W.,J . SOC.Chem. Obsvd.
Ind., 62, 148-60 (1943).
23
Black, H. G., Fruit Products J . . 22, 370-7 (1943). Burton, W.G., J . SOC. Chem. I d . , 64, 215-18 (1945). Campbell, H., and Kilpatrick, P. JT'., Fruit ProductsJ., 25, 106-8,
380 320 70 140 130
Cruess, 15'. Y.,and Mackinney, G., Univ. of Calif. dgr. Expt. Sta., Ru22. 680 (1943). Cruess, W. V.,Balog, E. G., Friar, H. F., and Lon.. M.,Canner.
62 50 150
120-1 119451,
.
4.6b 4 5.2b 3:66 1:iO 120 * 2.5% extract, 1-cm. cell, wave length = 390 mil. b Received a t specification moisture content (19) and further dried a t Western Regional Research Laboratory.
of storage, and the sulfite and the moisture contents of the product. 2. The effect of oxygen on the browning rate of the four dried vegetables is relatively small for samples stored a t moisture contents near commercial levels. 3. The browning rates of the four dried vegetables mentioned vary exponentially with the reciprocal of the absolute temperature. The temperature coefficient of the process is high, the Q l 0 values ranging from 5.0 t o 8.4 among the four vegetables. The estimated energy of activation varies from 32 to 42 kg.-cal., depending upon the vegetable. 4. The browning rates of the four vegetables vary exponentiaJly with the moisture content over the range studied. a. Estimated browning rates for dried nonsulfited carrot, white potato, and sweet potato, a t the same conditions of temperature and moisture content, are in the ratio of 27:3.3:1. ACKNOWLEDGMEIVT
The authors wish t o acknowledge the cooperation received from their co-workers, especially C. E. Hendel, L. R. Leinbach, .II.F. Pool, D. C. Patterson, and N.Floy Bracelin, who made the drawings. They also wish to acknowledge the unfailing interest
98 (5), 18 (1944).
Cruess, W.V , Balog, E. G., Friar, H. F., and Low, M., Food Packer, 25 ( l ) , 31, 62 (1944).
Davis, IM. B., Eidt, C. C., Macilrthur, &I., and Strachan, C. C., Proc. Inst. Food Tech., 1942, 90-8. Denny, F. E., and Thornton, N. C., Contrit. Boyce Thompson Inst., 12, 217-52 (1941). Ibid., 12, 361-73 (1942). Gore, H. C., and Mangels, C. E., J. IND. ENG CHEM.,13, 523-4 (1921).
Gore, H. C., and Rutledge, L. F.. Chem. .4ge (N. Y.), 29, 457-8 (19211.
Mackinney, G., Friar, H. F., and Balog, E., Fruit Products J . , 22, 294, 315 (1943).
Makower, B., Chastain, S. M.,and Nielsen, E.. IND.ENO. CHEST., 38, 725-31 (1946). Mangels, C. E., and Gore, H. C., Ibid.. 13, 525-6 (1921). Prater, A. Ii.,Johnson, C. M,, Pool, M. F., and Mackinney, G., I N D . EXG.CHEST.. k i . 4 L . E D . , 16, 153-7 (194'k). Stadtman, E. R , Barker, H. A , , Haas, V.,and Mrak, E. >I., IND. ENG.CHEM.,38, 541-3 (1946). Tomkins, R. G., Mapson, L. W., Allen. R. J. L., Wager, H. G., and Barker, J., J . SOC.Chem. Ind., 63, 225-3 1 (1944).
U. S. Army Quartermaster Corps, Tentative Specifications 59H and 7 3 D (1945). U.S. Dept. of Xgr., -\fisc. Pub. 540 (1944). PRESEXTED a8 part of the Symposium on Nonenzymatic Browning in Food stuffs before the Division of Agricultural and Food Chemistry a t the 110th Meeting of the AMERICAX C H E m c a L SOCIETY, Chicago, Ill.
Solubility QfSilver Selenide and Silver Telluride in Aqueous Ammonia R . S. YOUNG AND A. GOLLEDGE Central Laboratory, Nkana, Northern Rhodesiu T h e solubilities of silver selenide and telluride in ammonia have been determined. Contrary to inferences in leading handbooks, silver selenide is soluble to the extent of only about 0.25 gram per liter of ammonia, whether the latter be 1 : l or concentrated, and at temperatures from 23' C. t o the boiling points. Silver telluride is practically insolublein 1 :lor concentrated ammonia, solubilitiesranging from 7 to 24 mg. ,per liter, depending on temperature.
I
N T H E couise of experiments on the leaching of copper refi-
nery slimes, the authors had occasion to investigate the solubility of silver selenide and silver telluride in ammonium hydroxide. '&'ell known chemical handbooks' state that silver selenide is soluble in aqueous ammonia and do not list the behavior of silver telluride in this solvent. Discrepancies in results of leaching tests, based on the belief that silver selenide lvas quite soluble in ammonia, led us to queqtion this assumption. 1 For example, Handbook of Chemistry and Physics, 26th ed , Cleveland, Chemical Rubber Pub. Co., 1943; Van Nostrand's Chemical Annual, 7th rd , Yew Tork, D. Van Nostrand Co., 1940.
-4search of the literature did not disclose additional information on this subject, and specially prepared samples of silver selenide and telluride in lump form were finally obtained from British Drug Houses Ltd., for solubility determinations. The samples were about 99.2% pure, a little metallic silver being present in both cases. These were ground to -200 mesh in an agate mortar for the solubility tests. This material was leached a t room temperature, 23' C., in concentrated C.P. ammonium hydroxide and in a solution containing 1 volume of the latter t o 1 volume of water, and at the boiling temperatures of these solvents. The latter were 64" C. for 1:l and 34'C. for the concentrated ammonium hl-droxide. The C.P. ammonium hydroxide had a specific gravity of 0.906 and contained 26.37, ammonia by might. This concentration of ammonia is typical of that supplied to tropical countries. Contact of the solid with the solvent was continued for a sufficient time to attain equilibrium. It required less than one hour at room temperature, with occasional stirring, to reach equilibrium with both selenide and telluride, and boiling periods in excess of 5 minutes did not rwult in anv increase of solubility. The influ-
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1300
TABLE I. SOLUBILITY OF SILVERSELENIDE AND TELLURIDE IN
AMMONIA ~i~~ of Contact, Rlin.
NHiOH Temp.,O C. Concentration
23 (room)
Concd.
23
1:l
30 60 240
0,0247 0.0261 0.0260
0.0004
30
0.0242 0.0262 0.0262
0.0005
20
5
0.0232 0.0249 0.0250
0.0012 0.0024 0.0023
2 5 20
0.0202 0.0239 0.0240
0.0009 0 0020 0.0020
60 240
34 (b.p.)
2
Concd.
64 (b.p.1
1:l '
Soly., GramilOO hl1. of Solrent AgaSe AgtTe 0.0008 0.0008 0.0007 0.0007
ence of time on the solubility of silver selenide and telluride is illustrated by Table I. After boiling for 5 minutes, the ammonia content had decreased to 8.4% by weight with the concentrated solution, and 3% by weight with the 1:l solution. Determinations of silver, selenium, and tellurium were made on the filtrate of the filtered samples. Silver was determined gravimetrically as chloride; selenium and tellurium were determined gravimetrically in the elemental state after precipitation by means of sulfur dioxide in accordance with the following procedures. Selenium was precipitated, after removal of silver as chloride, by addition a t 20" C. of 80% by volume of concentrated hydrochloric acid saturated with sulfur dioxide, stirring, allowing the red selenium to settle overnight, and filtering on a Gooch crucible.
Vol. 39, No. 10
The precipitate was washed thoroughly with cold concentrated hydrochloric acid and in succession with cold water, alcohol, and ether. The selenium was dried at 40 O C. for 3 hours and a t 120' C. for 2 hours. Tellurium was precipitated, after the removal of silver as chloride, by heating the solution containing 25y0 by volume hydrochloric acid to boiling, adding 15 ml. of a saturated solution oj sulfur dioxide, 10 ml. of a 15% solution of hydrazine hydrochloride, and another 25 ml. of the saturated sulfur dioxide solution. Boiling was continued for 5 minutes; the tellurium was allowed to settle 15 minutes and was then filtered on a tared Gooch crucible. The precipitate was washed quickly with hot water and finally Tvith alcohol, dried at, 105' C., and weighed. The following results indicate the degree of precision experienced in this work (in grams per 100 ml. of solvent ): AgCl
8e
T.?
0,0506
0,0140 0,0141
....
.... ....
0.0031 0. 0029
0,0509 0.0070 0,0066
....
I n all cases the combination of silver, selenium, and tellurium determinations gave the theoretical composition of silver selenide and silver telluride within the limits of experimental error. From these results the solubilities of silver selenide and t,elluridr (Table I) were determined. It is obvious that silver selenide is unlp sparingly soluble in ammonium hydroxide solutions, and increase of ammonia concentration or of temperature does not increase the solubility of this compound. Silver telluride is virtually insoluble in either cold or hot ammonia solutions, although the percentage increase ol solubility ait'h temperature is appreciable.
Production of Benzyl Benzoate LABORATORY AND PILOT PLANT STUDIES I. D; THARP' AND H, 4. NOTTORF Edgewood Arsenal, .Md.
C.H. HERR2,T. B. HOOVER, R. B. WAGNER, C. -4.WEISGERBER3, J. P. WILKIn'S2, AND F. C. WHITMORE4 The Pennsylvania State College, State College, Pa.
I
NVESTIGATIOKS have been in progress for the preparation of benzyl benzoate, a miticide, by means other than its standard preparation from compounds derived from toluene. The most promising process has been the conversion of benzene to benzyl chloride by chloromethylation (Equation 1) and the dry esterification of the latter with sodium benzoate in the presence of triethylamine (Equation 2).
ZnCL
CaHe
+ (CHZO), + HCl -+C,H6CH&1 + H20
+
C6HaCH2C1 C6H&OONa
EtaX
(1)
+
C6H,COOCH2CBH, NaCl (21
The first step in this process has been reported (5). Rueggeberg, Ginsburg, and Franta ( 3 ) have reported some laboratory results on the dry esterification step. I t is the purpose of this report t o 1 Present 1
address, Paper Manufacturers Company, Philadelphia, Pa. Present address, E. I. d u Pont de Nemours & Company, Ino., Buffalo,
N. Y. * Present address, Hercules Powder Company, Ino., W-ilmington, Del. 4 Deceased J u n e 24. 1947.
give additional laboratory data and also pilot plant data for thie reaction. Considerable work has been done on the preparation of benzyl esters under anhydrous conditions, The methods have been revieoi-ed by Gomberg and Buchler (2). For the most part long periods of heating a t high temperatures were required, and in many cases low yields of the esters were obtained. Preparation of the benzyl esters in the presence of organic bases is first described in a patent assigned to the Badische Anilin- & SodaFabrik ( I ) , and Volwiler and Vliet ( 4 ) have prepared certain benzyl esters using diethylamine as a catalyst. LABORATORY STUDIES
In the laboratory, the procedure for the dry esterificatioii uf benzyl chloride was modified to allow a study of the following (a) reaction using either an excess of benzyl chloride or sodium benzoate; ( b ) reaction using slightly acid (benzoic acid) or alkaline (sodium hydroxide) sodium benzoate; ( c ) reaction in the presence of iron filings; ( d ) reaction in the presence of dried and undried benzene; and ( e ) reaction using a chloromethylation reaction mixture as the source of benzyl chloride.
