June, 1941
INDUSTRIAL AND ENGINEERING CHEMISTRY
The methallyl xanthate can be used for recovering minerals from ores in a flotation process (4).
Literature Cited (1) Burgin, Engs, Groll, and Hearne, IND.ENG.C H ~ M31, . , 1413 (1989). \___.,
(2) Dolgorukovs-Dobryanska, J. Russ. Phgs. Chem. Soc., 57, 283 (1925). (3) Groll, U. S. Patent 2,011,317 (Aug. 13, 1935). (4) Ibid., 2,101,647 (Dee. 7, 1937). (5) Ibid., 2,101,649 (Dee. 7, 1937). (6) Groll and Burgin, Ibid., 2,055,437 (Sept. 22, 1936). (7) Ibid., 2,122,812 (July 5, 1938). (8) Groll and Hearne, Ibid., 2,042, 224 (May 26, 1936).
(9) (10) (11) (12) (13) (14) (15) (l6j (17) (18) (19) (20) (21) (22)
809
Ibid., 2,046,556 (July 7, 1936). Ibid., 2,078,534 (April 27, 1937). Ibid., 2,105,284 (Jan. 11, 1938). Ibid., 2,122,813 (July 5, 1938). Ibid., 2,164,188 (June 27, 1939). Groll and de Jong, Ibid., 2,042,220 (May 26, 1936). Groll and Ott. Ibid.. 2.097.154 (Oet. 26. 1937). Groll and Tamele, Ibid., 2,010,076 (Aug. 6, 1935). Ibid., 2,010,358 (Aug. 6, 1935). Lewin, Arch. ezptl. Path. Phurmokol., 43. 351 (1900). Muller, Be?., 6, 1445 (1873). Pogorshelski, J . Russ. Phys. Chem. SOC.,36, 1129 (1904). Sheshukov, Ibid., 16, 478 (1884). Tamele, Ott, Marple, and Hearne, IND.ENG.CHEM.,33, 115 (1941).
Control of Gelling in Vulcanizing Cements Nitroparaffins and Chloronitroparaffins as Inhibitors A. W. CAMPBELL, Commercial Solvents Corporation, Terre Haute, Ind. 1-Nitro-2-methylpropane is an effective antigel or vulcanization inhibitor in rubber cements containing ultraaccelerators but is definitely inferior to l-chloro-l-nitropropane. The latter may be used in a wide group of cements, but not in the presence of strongly alkaline agents such as lime or magnesia or of an accelerator as alkaline as diphenylguanidine. HE broad application of ultraaccelerators to vulcanizing rubber cements has been handicapped by the formation of irreversible gels, presumably due to partial or complete vulcanization while in solution. The gelling tendency can be overcome by the use of the so-called two-part cements as illustrated in recipe I. Rubber, zinc oxide, and sulfur are mixed on the usual type of mill and then dissolved in a suib able solvent to form one part; rubber and the accelerator or accelerators, with or without zinc oxide and similarly millmixed, are dissolved in the same solvent to form the second part. Mixing these two parts in the proper proportions produces a cement containing all the necessary ingredients in the proper proportions for vulcanization. With ultraaccelerators the mixed cement gels or vulcanizes within a period of hours or days, depending upon the accelerator used and the accelerator-sulfur ratio. The gel constitutes an economic loss. While two-part cements overcome this gelling, they are not economical of labor and space. It has been found that the nitroparaffins' and their derivatives will inhibit gelling of vulcanizing cements for long
T
1 The use of nitroparaffins and their derivatives as antigel agents for rubher cements is covered by patent applioations assigned to the Commercial
Solvents Corporation.
periods. Thus, with many accelerator-sulfur combinations it is possible to make direct mill mixes, followed immediately by churning in the solvent containing the antigel agent. This eliminates half of the mixing and churning usually necessary with ultraaccelerated cements and permits any unused cement to be stored for use later.
Nitro- and Chloronitroparaffins as Rubber Solvents Tests with masticated pale crepe indicate that the nitroparaffins are not solvents for rubber in the usual sense, whereas certain members of the chlorosubstituted nitroparaffins are good solvents. The solvent power of the latter varies with the structure of the compound. In the tests outlined in Table I the following two part cement was used, made up to 10 per cent rubber content with benzene as the solvent: RECIPEI Pale crepe rubber Zino oxide Sulfur Zinc dibutyl dithiocarbamate
A 100.0 0.5 2.5
B 100.0 0.5
... -
i:o -
103.0
101.5
To the indicated quantity of the mixed cement (Table I) small amounts of the compound to be tested were added, followed by vigorous shaking. This was continued until a precipitate of rubber appeared that would not redisperse on shaking, or until it was evident that no precipitation would occur.
Accelerated Gelling Test It was obvious that storage a t room temperature would require too much time before gelation occurred. I n addition, room temperature varied too greatly with the seasons. Also, the compound given in recipe I proved slower in rate of gell-
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
810
Vol. 33, No. 6
to give rapid gelling but not high enough to cause an excessive loss of solvent through the stoppers. The gelling time was taken as the period from immersion t o the time the gel became too stiff to flow when the test tube was inverted (Table 11).
Effect of Solvent on Action of Antigel The concentrations of the antigel used in Table
I1 were not directly comparable and obviously higher than necessary for adequate protection; therefore in the following tests lower concentrations were adopted. Rubber cements are normally prepared in benzene or naphtha, or occasionally in chlorinated solvents such as carbon tetrachloride or ethylene dichloride. Tests were run on cements containing 10 per cent rubber made up in benzene, naphtha, and ethylene dichloride, respectively, according to the following recipe: RECIPEI1
115.0
RECOVERY TOWERAT
THE NITROPARAFFIN PLANTOF COMMERCIAL SOLVENTS CORPORATION
ing than was desirable, so a change in acceleration was made. Zinc dibutyl dithiocarbamate is an ultraaccelerator, but to achieve faster action, polybutyraldehyde aniline was added to the mix. This cement gelled with commendable speed. Room-temperature storage was still too slow, so the following technique was employed. A 25 X 200 mm. Pyrex-rimmed test tube was filled to about the three-quarters point with the cement to be tested, loosely stoppered with a labeled cork stopper, immersed in a water bath, and maintained a t 50" * 0.1" C. until gelling occurred or the test was terminated. The stopper was tightened after the contents of the tube had reached the temperature of the bath. A temperature of 50" C. was selected as being high enough
TABLE I. EFFECTOF NITRO-AND CHLORONITROPARAFFINS ON SOLUBILITY OF RUBBER IN A 10 PERCENTRUBBER-IN-BENZENE CEMENT VOl. of Cement. Cc. 20 20 20 20
20 _.
20 20 20
10
10 10
Organic Compound Nitromethane Nitroethane 1-Nitropropane 2-Nitropropane 1-Nitro-n-butane 2-Nitro-n-butane 1-Nitro-2-methylpropane 2-Nitro-2-methylpropane 1-Chloro-1-nitropropane 1,l-Dichloro-1-nitropropane 2-Chloro-2-nitropropane
Val. Used, CC. 7 14 26 22 64 61 54 39
50 50 50
a These were a t all times smooth homogeneous cements.
Result Pptn. Pptn. Pptn. Pptn. Pptn. Pptn. Pptn. Pptn. N o pptn." No pptn.0 N o pptn."
102.0
The cements were made up to 10 per cent rubber concentration but diluted to 5 per cent when tested. From the accelerated test results a t 50" C. reported in Table I11 it is evident that the cements containing 1-nitro-2-methylpropane were protected only when benzene or ethylene dichloride was used as the solvent. 1-Nitro2-methylpropane in a naphtha cement is a gelling agent. 1-Chloro-1-nitropropane is an active inhibitor of gelling in any of the various cements
IN AN ACCELERTABLE 11. NITRO-AND CHLORONITROPARAFFINS ATED TESTAT 50" C. IN BENZENE^
Vo1.b Used, Cc.
Antigel
Hours t o Gel
4.6 Blank 10 Nitromethane 56 Nitroethane 44 1-Nitropropane 32 2-Nitropropane 120 1-Nitro-n-butane 192 2-Nitro-n-butane 164 1-Xitro-2-methylpropane 44 2-Kitra-2-methylpropane N o t gelledc 1-Chloro-1-nitropropane Not gelled0 1,l-Dichloro-1-nitropropane Not gelledc 2-Chloro-2-nitropropane a 10 cc of cement was used in each test. b The bolume of the antigel was slightly less t h a n t h a t required t o cause precipitation of t h e rubber. c After 1 month. OF SOLVENT ON THE GELLING OF VULCANTABLE 111. EFFECT IZING CEMENTS
Antigelling Agent None 1-Nitro-%methyl1-Nitro-2-methylpropane I-Chloro-1-nitropropane
Benzene Hours togelat %a 50' C . 33.5 0 1 39.5 39.5 5 54 57.5 10 a,." IU
3:::
1
63.5
Naphtha Agent Hours used, t o g e l a t '%" 50' C. 0 1 1 144 32.5 132.5 1 5 118 10 I" 108 1
201 20 1
Ethylene Dichloride Agent Hours used, t o g e l a t %a 50' C . 0 87 1 96 5 111 10 Not gelledd Not 1 ge11ed d 5 h'ot gelledd 10 Not ge11ed d
Not gelled0 Not Not 10 gelled0 gelledb a yo b y wei h t based on total weight of cement. b After 421%0urs. 0 After 411 houra. d After 284 hours 5
162
5
10
INDUSTRIAL AND
lune, 1941
EMISTRY
811
EQUIPMENT IN THE NITROPARAFFIN DERIVATIVES BUILDING tested; it is particularly active in the ethylene dichloride cements. Since many halogen derivatives of the nitroparaffins were available, they were tested as antigels for rubber cements. Table IV presents the results of tests in a ben~enecement on these compounds and others of related structure. The cement was the same as that used in Table 111, except that halogen derivatives of the nitroparaffins were substituted for the nitroparaffins and only in the benzene cement. TABLEIV. EFFECT OF ACCELERATED STORAGE TESTON HALOGEN-SUBSTITUTED NITROPARAFFINS IN BENZENE Compound Blank 1-Chloro-l-nitroethane 1 1-Diohloro-1-nitroethane lkhloro-1-nitropropane
1,l-Dichloro-1-nitrourouane
2-Chloro-2-njtropropani 2-Chloro-2-nitrobutane 1-Chloro-1-nitro-2-methylpropane Chloroform Carbon tetrachloride Nitrobenzene 0 After 459 hours.
7
Adcfed
0 5 5 5 5 5 5 5 5 5 5
Hours t o Gel a t 50' C. 38 Not gelleda Not gelled" Not gelled' Not gelled"
80
74 329 38 38 38
1-nitropropane was used exclusively, as it was considered the best from many angles.
Storage at Room Temperature While it has been demonstrated that these materials are effective as antigels at temperatures quite out of normal storage conditions, reactions differ a t different temperatures; therefore tests a t room temperature were run (Table V). All samples were stored in screw-capped glass bottles in a cabinet maintained a t 82' * 1' F. (28" * 0.5' C.). The milling time, aging period before dissolving, and churning period were varied separately. Two types of rubber were used-a blend of plantation crudes for one series and latex-
TABLEV. EFFECT OF VARIATION IN MILLING, AGING,AND CHURNING PERIODS ON BENZENE CEMENTS Milling Time Min.'
Agin Perioj,
Churning Period,
10
10 10 10 15 15 15
0 0 72 72 0 0 0 0 0
24 24 24 24 48 72 24 48 72
15 10
0 0
24 24
10 10
Any of the 1-chloro- or 1,l-dichloro-1-nitroparaffinstested are quite effective in cements with acceleration of this type. The compounds substituted in the 2 position are inferior to those substituted in the 1 position although they possess definite protective qualities. The dichloro-substituted products are as good as the monochloro-substituted. The failure of chloroform, carbon tetrachloride, and nitrobenzene to prevent gelling was as expected. I n the remainder of the test l-chloro-
a After
Hr.
6.5 months.
Hr.
Blank, days
Gelling Time at S2O F. 1-Nitro-2-methyll-Chloro-1propane, days nitropropane
Rubber Blend 4
4 3
a
5 4 6 5 4
a
8 10
10 10
9 11 12 11
Latex-Sprayed Rubber 11 31 8 30
5 mo. 11 days Not gelledo Not gelled' 6 mo. 10 days 6mo. Odays 3 mo. 13 days 6 mo. 0 days 4 mo. 10 day8 5 mo. 9 days Not gelleda Not gellede
812
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLEVI. EFFECTOF LOADINGAGENTSON ANTIGELACTION Recipe Rubber Zinc oxide Sulfur Zinc dibutyl dithiocarbamate Polybutyraldehyde-aniline Whiting Magnesite Lithopone Titanium dioxide I-Chloro-1-nitropropane
100 5 3 0.5 0.5
100
... ... . ..
100 5 3 0.5
100
5 3 0.5 0.5
.0. ,. 5 .... .. ... 100 ... .. .
100
100
5 3 0.5 0.5
.0 ...5 ..... . *
*.
. .. 100
100
100
100
Gelling Time a t 50' C. 31 31 Without I-chloro-1-nitropropane,hr. 16 With 1-chloro-1-nitropropane, days Not gelled= a After 5 1 days.
31 35
22
100
100
5 3 0.5
51
.. . ...
100 22
Not gelleda
sprayed rubber for another. Some were milled 10 and some 15 minutes on a 6 X 12 inch laboratory mill with a roll tem-
Vol. 33, No. 6
perature of 140-150" F. (60-66" (3.). The benzene used in this series was redistilled and dried over calcium chloride. Table VI presents data showing the effect of various loading agents on the gelling of the cements and on the action of the antigel. It is apparent that many loading agents can be used in the presence of 1-chloro-1-nitropropane. However, various tests indicate that strong bases form complex salts with the antigel and thus destroy the value of the cement. For example, diphenylguanidine cements cannot be cured because of this salt formation. Lime and magnesia combine with the antigel and thus prevent its exercising any inhibitory action. The bonding power of the cements is not affected, although the rate of cure may be decreased somewhat by the retention of traces of the antigel in the film. PRESENTED before the Divlsion of Rubber Chemistly at the 97th Meeting of the Imerican Chemical Soclety, Baltimore, Md.
Distribution of Nicotine and Its Corn= Pounds between Water and Vegetable Oils L. B. NORTOK New York State Agricultural Experiment Station, Geneva, N. Y
The distribution of nicotine and several of its compounds between water and a number of vegetable and other oils has been determined at two concentrations in order to estimate the suitability of these combinations for insecticidal sprays. Most of the vegetable oils, particularly those with free alcohol groups, hold more nicotine than the mineral oils. The nicotine compounds give a less favorable distribution than free nicotine but tend to shift less toward the water with increasing concentration. The vegetable oils and a few of the nicotine compounds offer some advantage over mineral oil in the distribution of nicotine between the components of the spray, but this advantageis too small to be a deciding factor unless these materials show additional desirable properties.
PREVIOUS communication (8) reported the distribution of free nicotine between water and petroleum oils, and its application t o the behavior of insecticidal sprays. The same type of information seemed desirable for vegetable oils, which because of their more polar character might be expected to show a greater affinity for nicotine than the mineral oils, and therefore t o hold a greater proportion of nicotine in competition with water. The limited information available on the insecticidal properties of the vegetable oils indicates that some of them may compare favorably with mineral oils in ovicidal effect and in safeness to foliage. It is therefore of interest to determine whether they possess any distinct advantages in a spray mixture, or a t least whether they may be substituted without loss of efficiency in case of high prices or limited availability of mineral oils.
A
Procedure One or more examples of each of the main types of vegetable oil were chosen. Pine oil was included because of its solvent properties, and neat's-foot, fish, and a medium petroleum oil were included for comparison. A sample of each oil was titrated with 0.1 N sodium hydroxide as a test for rancidity and acidic impurities. The acid numbers are included in Table I. None of the acid numbers appear seriously higher than those to be expected in fresh oils. The nicotine was purified by the method of Rata (3) as in the previous work on distribution. I n addition to free nicotine, a number of oil-soluble nicotine compounds were included in the-present work because of the lower volatility of the compounds and the possibility of a greater affinity for the oil because of structural similarity. These compounds were made by direct mixing of nicotine with the calculated amount of pure acid. The naphthenate was made from naphthenic acid furnished by the Shell Oil Corporation, purified by steam distillation, and titrated t o determine its effective equivalent weight. The technique for the determination of the distribution ratios was the same as that used in the previous distribution work, gravimetric analyses being made throughout. Tests showed that the nicotine was quantitatively extracted from the oil by hydrochloric acid even in the presence of oilsoluble organic acids. The distribution was determined at only two concentrations, 0.1 and 5 per cent, which represented approximately the concentrations to be expected in a spray mixture soon after application and a t the time of near dryness, respectively. The ratios determined a t the 0.1 per cent concentration of the compounds represent only approximately the distribu-
