April 1951
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
Reference has b e m made ( 1 ) to the effect of surface area on leaching rates. In Figure 1 initial leaching rates as a function of grinding time are shown for all pigments in formula 1, and Figure 2 represents similar data after 3 months. Similar curves were obtained after 2 weeks’ soaking until the end of the experiment. Thus further evidence is available t h a t only initial leaching rates arc affected mnterinllg by pigment particle size. CUPRIC OXIDE
Inasmuch as reports have indicated that paint prepared from pigment containing excessive amounts of cupric oxide shows decreased efficiency, the role of t h e higher oxide was studied as it might affect leaching rate and antifouling proficiency and effects discernible in the physical properties of the paint itself. Accordingly, about 75 samples of stored cuprous oxide obtained from the Sorfolk Kava1 Shipyard were analyzed for cupric oxide, after which a selected number were ground into formulas 1 and 2, and forwarded to the JVoods Hole Oceanographic Institution for leaching rate determinations. Leaching rates a t the end of 5 months for the pigment dispersed in formula 1 are shown in Figure 3 as typical of all those obtained. It is apparent t h a t cupric oxide content bears no direct relation to the leaching rates of the paint when the cupric oxide does not exceed 157;. Exposure studies at Miami Beach showed no appreciable fouling on the same paint a t the end of 6 months. Manufacturing personnel handling copious quantities of cuprous oxide have reported that in instances where the oxide s h o w evidence of heavy cupric oxide formation (dark color) considerable dusting occurs, making the pigment more disagreeablr to handle. Electron photomicrographs of these pigments revealed that pure cuprous oxide consists of fairly well defined culms n i t h relatively sharp boundaries regardless of its mode of formation--that is, electrolytically or pyrochemically. As the percentage of cupric oxide increases, the well defined shape of t h e partirles begins to disappear and a ragged or fuzzy appearance develops along the boundaries, which may be seen in Figures 4 through 7. This s e e m to indicate t h a t n.ith oxidation to the higher oxide, the cuprous oxide particles are enveloped by a thin dark layer which has a different crystal formation and is generally of much tiner particle size and perhaps of lower density, accounting in part for the bad dusting reported where cupric oxide is present in appreciable quantities. Little or no difference is perceptible in the visual
935
appeuance of samples varying between 2 and 167” cuprir oxide, indicating further the complete envelopment of the part,icles with the formation of minute quantities of cupric oxide. Because paints containing pigment of high cupric oxide content show no depression in leaching rate, it is suggested that, during grinding the layer of the higher oxide is completely removed, renewing the surface of t.he more active cuprous oxide. Otherwise, depressed leaching rat,es could be expected, as well as low antifouling proficiency, as the negative value of cupric oxide itself as an antifouling pigment has h r n ~ ~ wtablished. 1 1 SUMhIARY
The effect of pigment particle size on leaching rates is critical only for initial values. The error in the leaching rate deternlination is smaller than that to be expected in the normal preparation of duplicate batches of paint, and the percentage error in leachirirs rate determinations is smaller after a steady state rate has been reached. T h r presence of cupric oxide in the form of a n env‘Iop(: surrounding the cuprous oxide is not so detrimental as has berri previously supposed. iipparently, this film of higher oxide is removed during the grinding operation, after which the usual properties of the paint may be expwted. ACKh-OWLEDGMENT
The authors wish to express their appreciation to €1. \V.Stewart, !or preparation of the paints required in this investigation and to the members of the staff of the Ft-oods Hole Oceanographic Tnstitution for the determinations of leaching rate. LITERATURE CITED
(1) Alexander, A. L., Ballentine, J. R., and Yeiter,
M.0.. IND.Kuc;. CHEM.,41,1 7 3 (194‘3). : 2 ) Alexander, A. L., and Benenielis, It. L., I b i d . , 41, 1532 (1949). ( 3 ) Alexander, -4.L., Renemelis, R. L., and Creoelius, Y. H.. I b i d . , 42, 1562 (1950). (4) Ketchum, B. H., Ferry, J. D., and Burlis, A. E., J r . , Ihirl. 37. 466-60 (1945) (5) Ibid., 38, 931 (1946). (6) Young, G. H., and Schnelder, W , K., IbLd., 35, 430 (194.3
RECEIVED J u n e 28, 1950. Presented before t h e Divislon of Paint, Varniah, and Plastics Chemistry a t the 118th Meeting of the . 4 a l E R I c A x C H E ~ I I C A L Y o c r m r . Chicago, Ill.
Stability of Fuel Oils in Storage EFFECT OF SOME NITROGEN COMPOUNDS R. B. THOMPSON, J. A. CHENICEK, L. W. DRUGE,
AND
TED SYJION
Universal Oil Products Co., Ricerside, Ill.
Filter and screen plugging precipitates that are formed in furnace oils frequently have significant amounts of nitrogen-containing material. Therefore, the effect of small amounts of nitrogen compounds (of the type that may be found in petroleum products) on the stability of the oil was investigated. Of the materials studied, pyrroles were found to cause the largest formation of precipitates. Pyridines were also harmful, but to a lesser extent than the pyrroles. Treatment with strong sulfuric acid removes the pyrroles, whereas caustic washing has little effect. The results of this work w-ith furnace oils point out one of the probable causes of precipitate formation, w-hich is
recognized as a major source of complaint with regard to oils used in domestic burners.
T
HE influence of small amounts of sulfur-containing compounds on the stability of fuel oils in storage has been investigated ( 7 ) . I n addition, actual experience has shown t h a t fueb oils obtained from high-sulfur crudes are ordinarily more prone to undergo deterioration during storage than are those obtained from low-sulfur crudes. The fact t h a t the precipitates contain more sulfur than the oil from whish they have separated has also been demonstrated. Nitrogen is another element t h a t ordinarily occurs in fuel oils, although usually in much lover concentration than sulfur.
936
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 43, No. 4
fairly high nitrogen content. -kidition of as little as 0 001% by weight of nitrogen as indole to a tuel oil originally giving a negative t(,st yields a product t h a t gives a positive test. QUALITATIVE DETECTION OF PYRROLES IN PETROLEUM FRACTIONS
S c o r ~ . This method can be used satisfactorily t o detect compounds containing the pyrrole nucleus in various petroleum fractioiis down t o concentrations as low as O.OOl7, by weight of pyi,rcilt:-t!ye nitrogen. For this method t o work, it is essential that t h i w be at least one hydrogen on a carbon atom of the pyrrole nucleus. Thus materials such t u indole and 2,bdimeth>.ll)yrrolegive a test, b u t completely substituted ones such as phyllopyrrole and carbazole do not. This method has not givcn satisfactory quantitative results.
..
DAYS STORED AT IOO'F
Figure 1.
Storage of 75% Catalytic-25q~Virgin Oil
(Illinois Crude) T h u s a nit,rogen content of 0.047, reportcd for wnie \Vj.oiiiing fuel oils is an unusually large miourit. IIowevcr, evcii wi1,Ii small amounts of nitrogen in the oil, precipitater which are much enriched in nitrogen are obt,aiiied, as shown for two catalytic cycle stocks in Table I.
KEAGESTR. pDiniethylaniinobenzaldehyde, methanol, acetic acicl, mercuric chloride, hydrogen sulfide, Skellysolve B (or equivalent), lead acetate paper, nitrogen or other inert gas, hydrochloric acid, Filter-cel. XPP.m.\,rm. Glass-stoppered Erlenmeyer flasks, funnels, filter paper, suction flasks. PRk:Pm.&mox OF Sor,irTIos5. Saturate distilled mater {vith niewwic chloride hy aliakiiig it at room temperature, using a n excess of the chloride. Filter out the excess of mercwic chloride just I)ct'nre use. PREP.IR.ITIOS O F EHRLICH RLICEXTR.Reagent I . 1)issolve 0 . j grmi of ptlimeth.ilamiii~~t~eiizaldehvde in 7.5 ml. of cniir.entrated hydrochloric acid and theri add 75 nil. of distilled water. Reagent 2. Dissolve 2 grams of p-diinetliylamiuohenznldehyde in 100 nil. of glacial acetic acid and then add 5 ml. of conceiitrated hydrochloric acid METHOD
Oil Catalytic Cycle Stock 1 2
Precipitate- .. .- , Sitrogen.
Sulfor.
Nitrogen.
Billfur,
1.28 0 . OG
0.01 0.02
:3.38 1 il'
%
%
70
5
3 . .i8 0.80
Because Table I indicates that nitrogen-contaiiiiiig nintcria1.q are important in formation of precipitate, an invcstigation was started t o determine what type of nitrogen coinpounds cause'; inst,ability. Bailey and co-workers ( 2 ) have made an cxtensivt. investigat,ion of the nitrogeri obtained from California stocks, isolating and ident.ifying e number of pure iii;iterials ified as substituted pyridince. l'otii I d ai. ( 6 ) noted t h a t not all nitrogen compounds could he c,xtrsctcltl froin the oil wit,h dilute acids. They suggested t h a t the nitrogen compounds which could not be estracted may be pyi'rolcs, iiidoleFI carbazoles, and/or heterocycles containing Imtli sulfur and nitrogen. hIapstone (5) has found pyrrole in thermal c~r~tc~lircl gaaoline produced from .lustra,lian shale oil. He alw found t h a t pyrroles strongly promoted formation of gum i n the gasoline. T h e Bureau of Mines ( 3 ) has found pyrrole in doiiiestic shalr oil. The esistence of substituted pyridinra in products from crudrsistcmw of pyrroles hne tietiii estahlislieci only for shale oils. In o r ~ i ( ~ toi ronfirin the r~ prcwncc. of pyrroles in distillates from crude oil, I ~ 4 o 1mwoediiig to investigate their effect, a numt)er of experiments \rerf> n ~ ( i r u-ith fuel oils of high nitrogen content. 1rifr:ired :t\worj)tiou techniques are of no v d u e , because the pyrrole nucleus does not have a characteristic absorption pat tern. T h e powiiiility of i i Ranian spectrum is poor, :ts it is t i o t puwihle t o o l ) t : L i i i csolorlt.+ solutions. A qualitat.ive test that will d i o w pyrroles coiitniiiing at 1e:tit one hydrogen o n one nurlcur carlion atom h:ts becn developcd by chemical means. 111 gcnrr:il, tlic nirt hod involves separating the pyrroles as a mercuric chloride comples, dccomposing the complex with hydrogen sulfide, nrid testing for pyrrolrr with Ehrlich reagent. This test could riot be made quantitative, becauw the mercuric chloride does not remove :ill of the pyrroles. Using this test, pyrroles have been found in most fuel oils of
T o 50 to 100 nil. of the material t'o be tested in a 230-ml. glass-stoppered Erlenmeyer flask add 15 nil. of mercuric chloride solution and 0.25 to 0.50 gram of Filt,er-cel. Shake for 5 minutes. Filter through a sniall Buchner o r IIirsch funnel with suction. Rinse the flask with four portions (15 to 25 ml.) of Skellysolve H :ind pour through the filter to wash out all the oil. Transfer the filter paper along with its contents to the original fhsk, add 15 to 20 nil. of met,hanol. and saturate with hydrogen sulfide with frequent shaking. Stmopperand shake 5 Iiiinut,es. Iq'ilter through a folded paper. The filtrate may he tested directly for pyrroles iiy splitting it into two equal portion8 and adding 2 to 4 nil. of Ehrlich rengent 1 to o n e half and 2 to 4 nil. of rmgerit 2 to the other half, The development of a i.cddish purple color iiitlicatc~sthe presence of pyri~nlw. 13erausr tlie coli) tion, it is desir:il)lc to dilute t,hr cr ani1 w e w h e t h i , t h e c i i l o i ~ :i1
INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1951
.I experience ,$ has &o\\-ti thxt hydrogen sulfide may interfere noiiie\\-hat with tlevelopnieiit of the color, it should be removed 1)ei'ui.e testing: Bubble a streani of nitrogen or other iriert gas f i n i n a fine capillary through the methanol filtrate until a pieccl oi moist lead acetate paI)er no longer s h o w t,he preieiice (if iivdrogen sulfide in the gas stream. Test with Ehrlich reagent :IS 1)rt'ore on this sulution no\v fwe of hydrogen sulfide. Suniplee were st,oretl, :w previously described, a t 100" F. (T) ; ~01~1Iile axtd insolutile gum \yere followed t o indicate st,itLdity i n stiJi':tge, (lolor \\-:is cleterniined o i i a Lumetron colorimeter, IIodel 4021.: ( 1 ) :iccordiiig to thi, A.S.T.IZ. photoelectricp C O I I I I ii i t l i ~ s ,
937
bility for further investigation. Consequently, a blend oi 50yo catalytic cycle stock and 50% virgin was procured from coast:il crude. This oil, originally containing no pyrroles ant1 only 0.2470 total sulfur, was used in subsequent tests wherein various nitrogen compounds were added to g i w conreritr:ttious of 0.1 to 0.01 7; of nitrogen and the resultant mixtures werv then storrtl ut 100" k'. D a t a are shown in Table I11 anti Figures 2, 3 , : i r d 4.
The harmful effect of a11 the pyrroles r a n be rlearly seen from t h r , data given, although t h y are b y no means equivalent in 1lic:ir
0
0 .iTc Siryopen
Sui.,
Insol.
21-24 Insol.
Sol,
effects; thus pyrrole promotes the formation of insoluble gum : I i l : l drgr:ides color. Indole itntl especi:tlly 2,5-dimethglpgrrole proniotr formation of insoluble gum hut improve the colui~of tho oil :tftrr filtr:ition. T h e strong promoting effect of the 2,5-tiiniethyl49-5i €4-89 _ _ . _ _ _ _ . pyrrolr is particu1:lrly strikiiiA: i r i the sample with 0.01% nitroSol. Insul, Sol. Insol. gen the amount of insoluble gum is dniost twice the quantity of tlirnethglp).rrolc~,indicating th:it rwctionr: other than mere polynit~riznt~ion I J ~ the pyrrolit are occurring. The pirticipation of niawri:il ot1ic.r than the p ~ ~ r i i Ii n( , s l u d g ~i'ormtttion is supportcvl
ST0R.AG E K E: SU LTS
As a preliminary esperinient, pyrrole and quinoline were addetl to a blend of i 5 % catalytic cycle stock and Xy0 virgin from Tllinois crude ( t h e original components contained no pj-rroles 1 i t i 1 ~ g timountj. r Results of storing thePe materials are shon.n i l l 'Table I1 and Figure 1. Inspection of these data shows t h a t pyrrole strongly promoter t h r formation of insoluble gum in the large amounts used here. Quinoline incremes soluble gum and degrades color; because t,he cliiinoline causes insolutile gum t o cling t o the container, detern~iiiationsof this propert,y ivere discontinued. T h e oil used in these experiments is very unstable by itself and i T :ipl)eared desirable to obtain a low-sulfur stock of 1iet)ter sta-
I
X - NO ADDITIVE
= I
I I I I 1 I I NO ADDITIVE I I l i CAUSTIC WASHED NO ADDITIVE 0 0.1% N AS INDOLE CAUSTIC WASHED 0 1 % N AS INDOLE 0 0. I % N AS INDOLE CAUSTIC WASHED HOT I
/
I
I
I
,
X
-0 -A
I
I
1
-- -
'
7
6
5 4
3 2
I
60
Figure
3.
90
120 1% DAYS S T O R E D AT
180 100'
Storage of 50% Catalytic-.50yc (Coastal Stock)
210
0
F.
b-irgin Oil
IO
DAYS STORED AT IOO'F.
Figure .5.
3torage of 50%
Catalytic-5070 (Coastal Stock)
Virgin Oil
INDUSTRIAL AND ENGINEERING CHEMISTRY
938
T4BLE
111. STORAGE
OF
50%
0 ____
Xitrogen Added F o additive
Sol. guma
Insol.
gumb
Sol. pun1
0
4
3
Days in Storage 50 69 Sol. Insol. Sol. Insol. Insol. gum gum gum gum gum 0.5 6 1.2 8 1.3 3.2 0.3 0.2 0.3 31.0 1.1 1.4 1.4
As -1)yrrole As 2,6-lutidine .Is isoquinoline A s quinoline As 2,5-dimethylpyrrole As indole As A'-ethylcarbazols As 2-aminopyridine
As 2,5-dimethylpyrrole As pyrrole .is indole
-
12
0.10%
0.010%
i
o
5
6 6
0 0
4
i.6
6
3 5 5 4 10 i 6
0.5 2.3 1.1 105 5.3 1.8 3.3
5 6
3
8.5 1 6 0 8
5
4
0.10% As pyrrole
As As As As As As
2.6-lutidine isoquinoline quinoline 2,5-dimethylpyrrole indole .\--ethy!carbaeole As 2-aminopyridine
0.010%
a
*
As 2,5-dimethylpyrro!e As pyrrole .Is indole Soluble gum mg./100 nil. Insoluhle gum, mg./100 mi A.Y.T.hl. color index.
____ 149
31.0 3.6 2.4
4
6
Days in Storage No additive
- -.. 216
.Is iiidolc, caustic washed A a indole, caustic washed hot As 2,S-diinethylpyrrole As 2,5-dimethylpyrrole, caustic n-ashed 4 s 2,5-dimethylpyrrole, caustic washed hot
61 1
8
23.8 3.0 6.7 3.0 466 9.2 2.9 6 3
15.0 37.5 30.0 19.0 56.5 49.5 27.0 17.5
4 8 9
94 8 10.6 6.5
.54.5 10.5
8
6.5
i 8 9
El 1 11).0 6.5
I? J
14 13
0 7 0 2 -10 1 1 6.0 29 60
5
53
201 -203 -~
12 8 17 13 1 :
2.2 0.g 9.1 3.6
ii;
I .3 298 318
6
103
10
284
1'2
96
or 28 0 41 5
18 0 4S.0
34.5
3
396
6
448
64.0 59 . h
3
362
6
436
59.0
2. I 0 8.7 2.7
16 6 8
8
( '01
? 'j.
10 8 13 11 1$5 6 3
11
1)ays in Storage ~.
I
3 4 1 0 7 0 189 218
1.2 7.1 80 116
!I
x n
2 0 8 3
10 8 1%
14 ti
5
43 0
l i 0.1 ti . :i
10
n a..lird hot
.Is i n d o ! c a
5
8 13
G.3 2 6 380 9.6 2.8
additive Caustic washed ', n o additive As indole As indole, caustic washed As indole. caustic washed hot As 2 5-di,nrrtiylliyrrole AE 2.,j-diiiiethylpyrrole, caustic
additive Caustic wuahed ', n u additive
42 5
13
5,s
166-173 10 3.1 7 0.5 12 9.6 -7 3.6 1; $7;
7 $ 2. 4 6
22.7 2 4
i8.0 9.1 5.9
-.
8
10 12 12 14 6 15
13
0
Y
Color 29.0
5 8 8
3
14
1.9 4.5
3.1
20.6 1.4 5.4 2.4 346 9.5 2 5
\\..1.1ICd
7.R
11
10 10 13 13 10 14 16 8
.Is ?..i-diniethylpyrrole, caustic
3 1 1.5 i 1.4 3.6 2 3
2.8
1.8
-
Insol. gum
11 8 10 11
i,; E
?
___
113
Sol. gum 1%
6 5 12 10 7 4
~~
12.4 0.6 3.9 2.4 154
15
181 _____
12
l";o
1-c
100' F
~ 4 T % L Y T I C - j 0 ~\rIRCrI.\T 0 FROM c 0 4 y P 4 L S T O C K i'I
Vol. 43, No. 4 aminopyridine degrade color. T h e quinoline, however, in t h e lower- concentration has little effect on soluble gum in contrast with the large concentration first investigated. T h e pyrroles have a promoting effect on insoluble gum, although they are by no means equivalent in their activities. It appears worth while to consider what types of pyrroles may be expected in petroleum distillates. Treibs (8) found that of 29 samples of petroleum 24 contained p o r p h y r i n s . Degradation of porphyrins leads to a complex mixture of pyrroles such as has been found in bone oil ( 4 ) . Destructive distillation of protein materials has also been found to yield a variety of pyrrole homologs (4:i. It. seems probable, therefore, t h a t the pyrroles that occur in fuel oil xi11 bc widely varjing in nature, r:tngiiiy from unsubstituted to tetrasubstituted. Pyrroles differ considerabljin their chemical propertie8for example, tctraallcyl pyrroles are slightly basic and soluble in dilute acids, wherepyrrole itself will form a salt when heated with potasjium hydroxide. T h e replacement of a-hydrogens with alkyl groups leads to pyrroles which are particularly subject to degradation upon contact with air. T h e facile degradation of the a-alkyl pyrroles may explain the great amount of insoluble gum with 2,s-dimethylpyrrole (ff,a').
Because some of the pyrroles are feeble acids, a n attempt w m Caustic washed a t I'oom temperature. Hot washed a t 90° C. made to see whether w-ashing with sodium hydroxide would improve the stability of fuel oils t o which they had been by the nitrogen content of the sludge. Thus sludge from a n oil added. Consequently, indole and 2,5-dimethylpyrrole were added ' nitrogen; 2,5to samples of the coastal blend and the resultant mixtures were containing 2,5-dimethylpyrrole contained 11.1% dimethylpyrrole contains 14.8% nitrogen. A'-Ethylcarbazole, washed with l / 6 volume of 25% sodium hydroxide both a t room which may be regarded as a tetrasubstituted pyrrole, causes t,emperature and a t 90" C. I n the case of indole, washing with virtually no change in comparison with t,he blank; unfortunately, the cold caustic gave a n appreciable improvement in comparison carbazole itself could not be investigated because it is too inWith the unwashed (Table I V and Figure 5). Hon-ever, hot soluble. caustic showed virtually no improvenient. This effect niight be expected from work with the extraction of other wealily acidic T h e iniprovement in color that prevails .rvith the samples that materials, the higher temperature increasing hydrolysis and decontain 2,5-dimethylpyrrole and indole is wholl>- unexpected. T h e only explanation t h a t can be offered is t h a t these niaterials creasing the amount of extraction. ?;either hot nor cold caustic give solid products which are extremely insoluble and which offer causes any appreciable difference in the samples containing 2,5a n active surface for the adsorption of any other colored bodies. * diniethy1pyrrole; presumably i t is relatively insoluble in caustic. On the other hand, compounds which may be classified as subThe fact that a fuel oil contains small quantities of pyrroles stituted pyridines have much less effect on formation of insoluble does not necessarily mean t h a t it will be unstable. T h u s several gum than d o the pyrroles. Isoquinoline and 2-aminopyridine oils have been found which give positive tests for pyrroles without increase the amount of insoluble gum, but the increase is conbeing especially unstable; usually the test for pyrrole is weak in siderably less than is obtained with the pyrroles. Quinoline arid thesr materials: but even oils that appear stahle in storage may Solubltt g u m nig./100 ml. Irisoluble gu;n mg./100 ml. 11s volume of 55% sodium hydroxide used. A.S.T.M. color index.
April 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
be made unstable by addition of small amounts of pyrrole. Thus a virgin stock which had only a small amount of insoluble gum after 6 months’ storage at 100” F. (0.15 mg. per 100 ml.) gave large amounts of precipitate in 4 wpeks when 0 01% of 2,sdimethylpyrrole was added. One method of improving unstable fuel oils involreq acid t rc=it,ing and, frequently, rerunning. Acid leads to extensive, pol\ merization of pyrroles t o high boiling products which remaiii 111 the acid phase or do not come overhead in the rerunning operation. llcid treatment of a sample of fuel oil originally containing a large quantity of pyrroles removed the greater part of the pyrroles and gave a more stable oil, especially with respect to color degradation. Pyrrole was readily removed from oils t o which synthetic pyrroles were added, by acid treatment and rerunning. T h e removal of pyrroles is undoubtedly one of the reasons why acid treating improves the quality of unstable oils, but i t is not necessarily the only reason. The removal of the substituted pyridine type of compound is easy, because they are relatively strong bases and are readily removed \\it11 even dilute mineral acids. I n the treatment of any distillate, in order to produce a stable product, there should he considered, among other things, the
939
nitro~c’i:(wrn[)oundst h a t may t,c present. If these cumpounde are ~ ~ ~ ~ ~ l ~pyridines i i ~ i their ~ ~ ~ removal : ~ ~ may i t ~not y bc necessary, t,ut i i i : i n > . ~ \ . o i i t will be ettsily arhieved. If the nitrogen compounc!. roiit:iiii appreciable amounts of pyrroles, it will lie necess:iry to I’PnlOVe at, least the more active portion of tlieni. Reinov:ti of thrse compounds will probably rrquire s o i n r drast io treatment such :is Ptrong .Gulfuric ncitl. LI’I‘EKATURE CITED
(1) Ani. For. Testing lfaterials, Philadelphia, “A.$.T.II. Standards on I’c\ti.oleum Prodiicts and Lubricants.” p. 615. October 1947 (2) Bailey, J. K., ~t ( I ! . , J . A m . (’hem. SOC., 55, 4136 (19:33): 59. 17.5 -. - llU37). ,.... ,.
(3) Ball, J. S., private communication. (4) Fischer-Orth, “Die Chemie des Pyrroles,” pp. 20, 32, Leipzig.
Akademische VerlagsgeSellschaft, 1934. (5) ,Mapstone, G. E., Petroleum Refiner, 28, 111 (Octoher 1949). (6):Poth et al., J. Am. Chem. Soc.. 52, 1239 (1930). (7) Thompson, R. B., Druge, L. W.. a n d Chenicek. .I. .t. I X D . ENG.CHEM.,41, 2715 (1949). (8) Treibs, A., Ann., 510, 42 (1934); 517, 172 (1935). RECEIVED August 4, 19.50. Presented beiore the Division of Patroleiim s SncimY, Chemistry at tho 1 1 8 t h l l e e t i n g oi t h e . - \ n ~ ~ r c aCHrirrcar. Chicago, Ill.
Chromatographic Investigations of Smokeless Powder DERIVATIVES OF ACARDITE, CARBAZOLE, AND TRIPHENYLAMINE FORNED IN DOUBLE-BASE POWDER DURING ACCELERATED AGING IT‘. A. SCHROEDER, BERTR.k\I KEILIN‘,
IND
K1C:HkRD \I. LE3\11110S2
California Institute of Terhnolopy, Pasadena 1. Calif. Thebe chromatographic-spectrophotometric studies of the reactions of acardite (1,l-diphenylurea), carbazole, and triphenylamine in smokeless powder during accelerated aging were made as a continuation of similar studies of diphenylamine ( 2 4 ) and centralite (25). Of the three compounds, acardite shows the most coniplex reactions, for i t is degraded, with the result that on11 derivatives of diphenylamine can he isolated. 0 1 1 the other hand, carbazole forms derivatives which would he predicted from its similarity in structure to diphenylamine, and triphenylamine in the main yields only simple
nitro compounds. The reactions of these st;tt)ilixers were followed quantitatively. In contrast to the complex and competing reactions of diphenylamine and centralite, the reactions of carhazole and triphenylamine seem to occur in stages such that compounds of the same degree of nitration do not react appreciahly until their precursors are depleted. The relative simplicity of the reactions may he of assistance in further study of reactions in smokeless powder. The chromatographic methods devised permit the separation of structurally related compounds.
M”“”
powder produced the grratest loss of nitrogen whereas diplii?iiyIamine caused the grrstest denitration of nitrocellulose i m t i nit roglycerin and the greatest lowering of viscosity. Carhzole, according to 1Iarqueyrol ( 1 7 ) , is better than diphenylamine as a stabilizer but does not form a very intimate mixture in the powder, as Dalbert ( l a ) also noted. Triphenylamine behaves much like diphenylamine if t,he quantity of either stabilizer is only 2% of the powder, but if it is 5%, triphenj-lamine produces less denitration and loss in weight ( I 1 ). The first product of reaction of triphenylamine is a niononitro compound and not a nitroso derivative as iF found in thc c:iw of diphenylamine (11 j. The present study of the derivatives formed from acarclite, carbazole, and triphenylamine was begun aft,er unpu1)lisheti experiments in these laboratories Kith various stability and surveillance tests showed t h a t these compounds might have merit aa stabilizers for smokeless powder, and after it was found t h x t
study has bern given to the reactions and use of diphenylamine and centralite as stabilizers in sniokeless powder, but little information has been published about powders which are stabilized wit.h acardite (1,l-diphenylurea), carhazole, or t,riphenylamine. Hecker and Hunold ( 1 ) described methods for thi, deterniination of acardite alone or in the presence of diphenylamine or centralite in single- or double-base pon-der. Tonegutti (26, 2 7 ) considers acardite t o he a more satisfactory stabilizer for nitrocrllulose than are diphenylamine or centralite, but reports th:it the latt,rr two are Letter and about equivalent for powdei.:: I J ~lo\\nitroglycerin content. Dalbert ( 1 2 ) found t h a t powders in which some ceiitralitr \\-as replaced by diphenylamine or carbazole did not behave as wrll in a n y respect as when centralite alone mi: present; carbazole in the 1
Present address, r n i r e r s i t y of Southern California, Los ;\ngeles, Calif. P r e w n t address. University of California, Berkeley, Calif.
