I N D U S T R I A L A N D ENGINEERING CHEMISTRY
November, 1924
magnitude with the quantities which exhibit distinct accelerating effects, and raises the question as to why the corrosive effect of some lots of straight commercial white arsenic had not been noticed. The investigation is being continued in an effort to see if other impurities present are taking part in the peculiar effects here noted. A different method of fo’lowing the course of the oxidation has been developed, but up to date only irregular results have been obtained and it begins to look as if adsorptive effects were being encountered in the apparatus, such as were mentioned by Klemenc and Pollak.
1171
CONCLUSIONS 1-The rate of reaction of solid white arsenic with 30’ BB. nitric acid varies greatly. 2-The reaction is stopped by the addition of mercury. a-White arsenic frequently contains mercury, and the reactivity Seems to bear a relation to the quantity present, if the latter is not too small. 4-The effect of the mercury can be counteracted by the addition of hydrochloric, hydrobromic, or hydriodic acid.
Nicotine Soaps’ By L. F. Hoyt LARKINCo., INC.. BUFFALO, N. Y
‘ICQTINE combines with many acids and salts to form definite compounds, and acts in most cases like a strong di-acid base.2 I n 1918, Moore3 described the preparation and insecticidal properties of a new compound, designated a soap or soap-like salt, formed by the union of commercial grades of free nicotine and oleic acid (red oil). A study has recently been made of the products formed by the union of chemically pure nicotine with purified fatty acids, as well as of the products similarly prepared from commercial grades of nicotine and fatty acids. Coconut oil, whose soda and potash soaps lather freely, and castor oil, whose soaps are characterized by very poor lathering qualities, were chbsen as the two extremes for
N
TABLE I-~OMPARISON OF NICOTINEAND
THE
oil. The nicotine soaps were easily made, the process being merely to mix, in the cold, equimolecular weights of nicotine and the fatty acid. Table I shows some of the properties of these pure anhydrous nicotine soaps. Particular attention is called to the unusual range of solubilities, in which the nicotine soaps have properties commonly associated, on the one hand, with fatty acids and, on the other, with soda or potash soaps. While soda and potash soaps are virtually insoluble in ethyl ether, petroleum ether, and carbon tetrachloride, these three anhydrous nicotine soaps are freely soluble in these solvents, with the notable exception that the nicotine-castor oil-fatty acid compound, like castor oil fatty acids, is insoluble in petroleum ether.
PUREANHYDROUS NICOTINESOAPSO F OLEICACIDAND OF COCONUT AND CASTOR OILS
OP THE
MIXEDFATTY ACIDS
t
Molecular weight of f a t t y acids Composition of soap: hTicotine per cent F a t t y acid, per cent Ratio, nicotine:fatty acid Original color Consistency, 20’ ,C. Behavior 011 chilling
Specific rotation, angular degrees, 1-dc. column Specific,gravity, 15,6°/15,60 C. Refractive index, 20’ C.
PURENICOTINE C I O H I ~ N ~ (MOL.WT. 162.2) OLEATE 282 3
COCONl’T FATTYACID S O A P OR “COCONATB” 209.1 (mean mol. wt.)
36.5 63.5 1:1.74 Very pale straw color Liquid Graduaily stiffens below \I -30 C., but remains perfectlyclear a t -78‘ C. although very stiff and “tacky” a t t h a t temperature
Amber Liquid
(-)
(-)
164.0 1.012 1.5262
Alcohol Ethyl ether Petroleum ether
Soluble Soluble Soluble
Carbon tetrachloride Water
Soluble Soluble
Glycerol
Soluble
Stiff, translucent Solid a t -23’ C.
40.4 0.948 1.4875
Solubilities Soluble Soluble Soluble Soluble Miscible 1: 1 to thick clear paste. Soluble in excess t o a turbid solution Soluble
comparison with oleic acid, whose soda and potash soaps have intermediate lathering and surface tension properties.
PUREANHYDROUS SOAPS The anhydrous products were prepared by combining 100 per cent pure nicotine with pure dry oleic acid and with the mixed fatty acids of edible grades of coconut oil and of castor 1 Presented before the Division of Agricultural and Food Chemistry a t the 67th Meeting of the American Chemical Society, Washington, D. C., April 21 to 26, 1924. 2 Beilstein, “Handbuch der organischen Chemie,” Vol IV, p. 854. J . Econ. Enlomol., 11, 341 (1918).
43.7 56.3
33.2 65.8
1:1.29
1:1.92 Amber Liquid
Amber Liquid
1
CASTOR F P T T Y ACID S O A P OR CASTORATE” 312.5 (mean mol. wt.)
Opaque solid a t -20’ C., Pour point, - 18’ C.
Stiff, clear solid a t Pour point, -26’
( - ) 48.5
(-) 2 9 . 9
0.956 1.4830 Soluble Soluble Soluble
- 2 9 O C. C.
0.980 1.4947
Soluble
Soluble Soluble Miscible 1:1, but insoluble in excess Soluble
Soluble to a clear solution Soluble
Soluble t o a clear solution Soluble
COMMERCIAL GRADES Commercial grades of nicotine oleate and of the nicotinecoconut oil-fatty acid compound were prepared and studied. The nicotine used was Nicofume, a 40 per cent solution of free nicotine. Commercial red oil (oleic acid) and commercial distilled coconut oil fatty acids were mixed with a quantity of Nicofume calculated to the basis of an equimolecular amount of pure nicotine. Table I1 shows some of the properties of these commercial nicotine soaps. Their solubilities, owing to the water they contain, are in some cases quite different from the solubilities of the corresponding pure an-
INDUSTRIAL A N D ENGINEERING CHEiWISTRY
1172
hydrous soaps. Both the pure and commercial grades are unstable on heating and lose their volatile base, behaving in this respect like the ammonium soaps. TAELE 11-COMMERCIALNICOTINESOAPS OLEATE PER CENT
COCONUT OIL-FATTYACID COMPOUND P E R CENT
Comgosition 23.5 41.2
Nicotine 26.3 F a t t y acid 34.2 Total active ingredients 60.5 (i. e., nicotine soa ) 64.7 Inert ingredients, ckefly 39.5 water 35.3 Color Very dark brown (like caramel) Dark brown Sirupy liquid, solidifyConsistency Soft paste ing t o stiff paste a t about 10' C.
Solubilities
No. 30 denatured alcohol Miscible and soluble t o Miscible and soluble t o turbid solution Virtually insoluble Miscible 1:1, only partly soluble in excess Virtually insoluble Miscible and soluble in all proportions t o clear solution Miscible and soluble t o turbid solution
Ethyl ether Petroleum ether Carbon tetrachloride Glvcerol Water
clear solution Virtually insoluble
Virtually insoluble Virtually insoluble Miscible and soluble in all proportions t o clear solution Miscible and soluble t o clear solution
COMPARISON OF SOAP-LIKE PROPERTIES OF PURE AND COMMERCIAL SOAPSOLUTIONS Comparisons were made of the soap-like properties of the pure and commercial nicotine soaps in solution, all the tests being made a t 20' C. The results are shown in Tables I11 and IV. TABLE 111-SOAP-LIKE
PURE NICOTINESOAPS Pure potash coconut oil soap; anhyPURE ANHYDROUS NICOTINESOAPS OF drous and glycCoconut oil Castor oil eroi free (for Oleic acid fatty acids f a t t y acids comparison) cc cc. cc cc.
.
(1) Distilled water 0.2% solution 0.5% solution
PROPERTIES OF
Lathering test
185 310
1% solution Not tested (2)H & d water (hardness 300 p. P. m. CaCOa) 0 0,5'% solution 25 1% solution
1% solution in
distilled water
153
415 630 Not tested
85 405 Drop number 201
.
0 10 100
Not tested
0 60
Not tested Not tested
232
500 950
430
LATHERING OR FOAMING PowER-This test is a measure of the surface tension of a soap solution versus air. A known weight of soap dissolved in 100 cc. of either distilled or hard water of known hardness is pipetted into a 1-liter, glass-stoppered cylinder, which is shaken for 1 minute in a mechanical shaking device, and the net volume of lather remaining after 1 minute subsidence is recorded. DROPNUMBER-This test is a measure of the interfacial surface tension between an unsaponifiable oil and the soap solution. The larger the drop number, the lower is the interfacial surface tension. A large drop number is usually considered indicative of good wetting and spreading properties. The apparatus used consists of a special brass stalagmometer pipet of about 5-cc. capacity and having a capillary opening 0.1 mm. in diameter. The pipet is filled to a definite level with a solution of the soap t o be tested and clamped in position with the capillary opening 10 cm. below the surface of 650 cc. of liquid petrolatum-i. e., medicinal mineral oil-in an 800-cc., tall beaker. The soap solution is allowed to flow into the oil and the number of drops formed is recorded. SURFACE TENSION BY DU NOUY SURFACE TENSIMETER-This tensimeter measures the force in dynes required to detach a platinum loop of 4-cm. circumference from the surface of a solution. The surface tension of pure distilled water as measured by this instrument is 77.7 dynes per centimeter a t 20" C., and the addition of small amounts of soap markedly lowers this value. SPREADING TEST(applied only to the 1:500 dilutions of the commercial nicotine soaps, this dilution representing a suitable concentration of nicotine for use as a contact insecticide)-A
Vol. 16, No. 11
piece of sheet metal was coated with a uniform thin layer of paraffin. From a capillary pipet 0.3 cc. of the soap solution was allowed to flow onto the paraffined surface, forming a single large drop. The diameter of this drop and the area to which it could be mechanically spread as a continuous film was measured. TABLE Iv-SOME
PROPERTIES OF COMMERCIAL NICOTINEOLEATE AND NICOTINE-COCONUT OIL-FATTY ACID COMPOUND IN SOLUTION COCONUT OIL-FATTY OLEATE ACID COMPOUND Concentration of soap solution in distilled water, except 1 part in 500 1 part in 500 as otherwise noted Concentration of nicotine in final 0.0470% 0.0528% solution
Droa number 82 98 Volume of drop Diameter of drop Area on which drop could be spread
Spreading test 0.3 cc. 1.1 cm.
85 160
.
70 sq. cm. Surface tension by Du Nouy surface tensimeter Dynes per cm. a t 20' C. 39.6 (Distilled water = 77.7 dynes) Lathering test 300 Distilled Distilled (hardness Hard water Solution
0.2% 0.5% 1.0%
water cc.
140 285 245
p. p. m. CaCOs) cc
.
.. ..
20
0.3 cc, 1.7 cm. 115 sq. cm. 30.0 (hardness 300 Hard water
water cc
p. p. m. CaCOs) cc.
225 390 735
230
.
..0
The results in Tables I11 and I V show a definite superiority of the nicotine-coconut oil-fatty acid compound over the oleate in both the pure and commerical grades, even in distilled water. There is a still more marked difference in favor of the coconut oil-fatty acid compound in hard water, because coconut oil soaps react much less readily than do the soaps of oleic acid with the calcium and magnesium compounds of hard water to form insoluble soaps. d
EFFECT ON INSECTS A survey to determine the suitable concentration was first made. Directions for the use of various preparations containing nicotine recommend quite generally a concentration equivalent to approximately 0.05 per cent nicotine in the spraying solution. The concentration chosen for tests on the commercial nicotine soaps, both oleate and the coconut oil-fatty acid compound, was 1 part in 500, using soft water. The nicotine soap solutions were compared for wetting power and effectiveness on the only available insects, as follows: green apple aphis (Aphis pomi) on young apple trees and current bushes; wooly aphis (Erisoma lanigera) on twigs of apple trees; and cabbage aphis (Aphis brassicae) on turnips and cauliflower. Both nicotine soap solutions (whose concentration of nicotine was practically 0.05 per cent) were found t o be very effective in kiIling the aphis, provided the spraying was done with sufficient thoroughness to reach and wet all the insects on the affected plants, The superior wetting and spreading power of the nicotine-coconut oil-fatty acid compound was particularly noticeable on the waxy leaves of the turnips and cauliflower, and on the downy young leaves of the apple. T o secure comparable wetting with the nicotine oleate, considerably more time, effort,and solution were necessary.
Brined Vegetables Studied The Bureau of Home Economics of the United States Department of Agriculture has recently cooperated with the Bureau of Chemistry in tests on the utilization of brined vegetables. These tests showed that green tomatoes, and green peppers particularly, could be kept successfully in brine for as long as six months and then used in a number of ways. Mock mince-meat, Bordeaux sauce, and pickle were all made from the green tomatoes, and the peppers were satisfactory for stuffing as well as for seasoning various dishes.
