I1VDrSTRIdL 9 S D ESGIiL'EERI*VG CHE+Vl'S'TRY
March. 1931
321
Action of Inorganic Refining Reagents on Alkyl Sulfides in Naphtha' P. Borgstrom and J . C. McIntire S~ v . 1 RE ~ S E A R CLABORATORY, H ~VASHIXGTD O .X C. ,
HE l i t e r a t u r e dealing
T
The effect of mercuric acetate and mercuric chloride
Treatment with Mercuric
Acetate solutions, solid mercurous nitrate, and silica gel on with the r r n i o r a l of fourteen alkyl sulfides in naphthas has been studied. known sulfides f r o 111 The niercuric acetate soluFour naphthas were used. Alkyl sulfides having two tion used was 0.5 nornial and naphtha by the use of inoror three carbons in the chain are almost completely freshly prepared. The naphg a n i c s a l t s is not large.? removed, while those with five or more carbons are tha was shaken with one-half Kood, Lowy, and Faragher but slightly removed, when using mercuric acetate or its volume of this solution, (6)stated in 1924 that nchloride solution. When a solid, such as silica gel, allowed to stand for 1 hour, butyl sulfide is not removed that has adsorptive powers is used, the removal is heparated, and washed with by coopper oxide. Faragher, dependent upon the length of carbon chain and there water three times. So test Morrell, and Monroe (3)have is no sharp break in the curve. Solid mercurous nitrate for mercury was given by used mercurous nitrate nioiioremoves the lower sulfides, but is not so effective with the naphtha after washing hydratr for the removal of sulthe higher secondary sulfides. with w a t e r . The per cent fides using methyl. ethyl, tiNaphtha 7 containing these sulfides was also treated propyl, isoamyl, and benzyl sulfur found in the naphtha with various other inorganic reagents. Solid zinc after this treatlnent is given sulfides as examples (1927). chloride, aluminum oxide, stannous chloride, cupric in Table I and F i g u r e 1. They also state that mercuric chloride, and cupric sulfide at room temperature were These r e s u l t s s h o w that chloride did not remove the found to remove sulfides to a small extent. the lower sulfides are more sulfur quantitatively and that readily removed by mercuric in some cases 40 per cent of the sulfide sulfur remained in the iiaplitha. Mercuric chloride acetate than the higher. The isobutyl and isoamyl sulfides has been used by hfaliery (4) for removal of sulfides from Ohio were removed about the same as the corresponding normal petroleum (1891) and by Thierry ( 5 ) for identification of sul- sulfides. see-Propyl and see-butyl sulfides were removed fides in Persian petroleum (1925). Youtz and Perkins ( 7 ) inore than the corresponding normals, but when the carbon chain had five or mere carbons the effect was yery small. studied the removal of et,hyl, isoamyl, n-heptyl, n-sec-4-heptyl, allyl, phenyl, and benzyl sulfides from naphtha Tvith silica Allyl sulfide was removed about the same as the corresponding propyls, but not so completely as ethyl. Changing gel (1927). I n this paper silica gel, mercuric acetate, mercuric chloride, the solvent did not affect the action of the mercuric acetate and solid mercurous nitrate are studied in detail as to their appreciably. efficiency in removing alkyl sulfides from naphthas, and sevenFound by Lamp Method after Treatment of Naphteen other compounds are studied with one naphtha but with Table I-Sulfur thas with Mercury Salts and Silica Gel various sulfides. SOLID S ADDED PLUS HgNOvSULFIDE S ADDEDBLANKS FOUNDH d 0 A c ) r HgClz HsO
Sulfides and Naphthas Used
C'
All the sulfides but the secondaries were purchased from Eastman Kodak Company. The secondary propyl, butyl, hexyl, and octyl sulfides were prepared from the corresponding bromides. All the secondaries were straight-chain with the sulfur on the second carbon atom. The melting or boiling points were as follows: SULFIDE Ethyl 72-Propyl Isopropyl .411yI it-Butyl Isobutyl sec-nutyl
31. P .
c.
-102
1
B.P.
SULFIDE
91.6
n-Amyl Isoamyl sec-Amyl sec-Hexyl 7z-Heptyl sec-Octyl Benzyl
c.
142 - 63.0
-
79.7
120.4 138.7 182 171 165
31. P.
c.
B . P.
c.
103-103 216 72-3 116-120 298 149
(12 m m . )
mm.) (12 mm.) ( 5
L
c' c
%
Vo
'6
%
SILIC~ GEL
,'
NAPHTHA 7
Blank Ethyl n-Propyl set-Propyl Allyl n-Butyl Isobutyl sec-Butyl n-Amyl Isoamyl sec-.4myl set-Hexyl n-Heptyl sec-Octyl Benzyl
O', 086 0.070 0.108 0.081 0.068 0 074 0 075 0,078 0 073 0,079 0.089 0.069 0.086 0.086
0:ii5 0.106 0.144 0.117 0 104 0 110 0.111 0.114 0.109 0.115 0.125 0,105 0.122 0.122
Blank n-Propyl
o'.OQ4
o.lb4
0.036 0.122 0.107 0.141 0 113 0,107
0.113 0.113 0 116 0.113 0 115 0.122 0.105 0.125 0.124
0 029 0,029 0 044 0,040 0 040 0 065 0 076 0 055 0 098 0 094 0 098 0 113 0 091 0.106 0,099
0:0i1 0.061 0.040 0,099 0.061 0 092 0,100 0 111 0.071 0.110 0.125 0.104 0.117 0.104
0.019 0,019 0.017 0.027 0,023 0.026 0 032 o 034 0.034 0.032 0.052 0.051 0,034 0.081 0.025
0.021 0.034 0,036 0.035 0,033 0,040 0,043 0.036 0.044 0 047 0.043 0.058 0.051 0.06,5 0.028
o'.oks
o.iiio
0.010 0.023
010i4 0.104 0.056 0.093
0 013 0.013 0.010 0 014 0.018
0.014 0.030 0.032 0.037
io09
tJ:0i8
NAPHTHA 4
(10 mm.)
f49
0.010 0.10~
o.oiz
NAPHTHA
3
The solutions were itnalyzed by the A. S.T. _\I.lamp method. The accuracy of this method can be seen from the values given in Table I. Allyl sulfide did not show the purity that the other sulfides did. With naphtha 7 the average difference between the blank plus the sulfide added and the value found was 0.0019 per cent. The naphthas used were the same as in the previous work ( 1 ) and are designated by the same numbers.
Blank n-Propyl Allyl n-Butyl n-Heptyl
Received October 2 5 , 1930. Published b y permission of the h-avy Department. 2 Of the many E. S. patents in which inorganic compounds are used for refining, the following are well worth examining: 63,749; 299,324; 400,633; 451,660; 551,941; 955,372; 962,641; 1,312,375; 1,457,656, 1,608,339: 1,655,069; 1,678,298; 1,678,299; 1,684,035; 1,687,992; 1,733,800; 1,771,350,
The mercuric chloride solution used was saturated. The naphtha was shaken for 3 minutes with one-half its volume of this solution. It was then allowed to stand and the naphtha was decanted through a dry filter, washed with water to remove any dissolved mercuric salt, and finally
c
0:077 0,091 0.079 0,073
Olio3
0,117 0,105 0.099
0.026 0 098 0.108 0.104 0,097
0.013 0 032 0 027 0.077 0.088
0.045
NAPHTHA 2
Blank Ethyl
o',ii3
...
0.123
0.010 o 118
.,. , . ,
... , , .
Treatment with Mercuric Chloride
Vol. 23, No. 3
INDUSTRIAL AND ENGIiVEERISG CHEXIXTRY
322 Table 11-Per
Cent Sulfur Found by Lamp Method after Treatment of Naphtha 7 with Inorganic Reagents nsecnIsosecnsecsccnsccAv. SULFUR NAPHTHAETHYLPROPYL PROPYL ALLYL BurvL B U T Y L BUTYL AMYL AMYLHEXYLHEPTYLOCTYLBENZYL REMOVED Grams/lOO cc. % % % % % % % % % % % % % %
REAGENT Zinc sulfide Cupric sulfide Ferrous oxide Ferric oxide Cupric oxide Cobaltic oxide Sickel oxide Mercuric oxide, yellow Lead oxide Aluminum oxide Zinc oxide Chromic oxide Basic copper carbonate Ferric nitrate Stannous chloride Zinc chloride Cupric chloride
Sulfur added Sulfur added plus blank Sulfur found
30 30 25 50 25 50 25 80 80 30 25 30 50 80 80 40 70
0.102 0.087 0.105 0.110 0.103 0.114 0.114
0.104 0.091 0.097 0.104
0.140 0.137 0.140 0.125 0.139 0.122
0.102 0.109 0.100
0.070 0.106 0.107
70 60 50 40
c
c
0
0.113 0.112
0.123
0.104
0.108 0,144 0.141
0 . 0 8 1 0.068 0.117 0.104 0.115 0.107
i 1
x
+NORMAL -SULFIDES *SECONDARY -SULFIDES
0.104
0.125 0.127 0.096
0.109 0.113
0.086
0.094 0,088
0.074 0,110 0.113
0,075 0.078 0,111 0.114 0 . 1 1 3 0.116
0 . 0 7 9 0.089 0.115 0 . 1 2 5 0.115 -0.122
0.069 0.105 0.105
0.086 0.122 0.125
-0.0015 -0.0110 -0.0030 0.0083 0,0018 -0.0037 0.0030 - 0.0040 -0.0015 -0,0197 -0,0045 -0.0120 -0.0093 - 0.0043 -0,0163 -0.0210 - 0.0100
-
0.120 0.098 0.111
0.086 0.122 0.124
+0.0019
was 0.015 per cent sulfur, while the average for the four sulfides after treatment was 0.014 per cent. n-Heptyl gave 0.018 per cent-a value slightly high but not more than 4 per cent. Naphtha 4, containing ethyl and n-propyl, showed the same per cent sulfur after treatment as the naphtha itself did under the same conditions. Allyl, secpropyl, n-butyl, and benzyl were 90 per cent or more removed, while isobutyl, sec-butyl, n-amyl, isoamyl, and n-heptyl were removed 80 per cent or more. Those sulfides not removed 80 per cent or more were the secondary amyl, hexyl, and octyl. From their boiling points it is questionable if much of the sec-hexyl or octyl would be in an ordinary gasoline sample and possibly not much of the sec-amyl. Faragher, Illorrell, and Monroe (3) studied methyl, ethyl, n-propyl, isoamyl, and benzyl sulfides and based their conclusions on the behttvior of these sulfides (1927). Of these it was found in this work that ethyl and n-propyl are completely removed, benzyl 90 per cent, and isoamyl 80 per cent. Unlessother difficulties occur, mercurous nitrate is the best available reagent for the removal of sulfides.
4
MERCURIC ACETATE
0.124 0.115
0.111
0.094
0.133
0.105 0.094
0.114
0,087
0.132
30 -
2
0.107 0.110
0.102
0.086 0.122 0.122
0.112
0.125 0,118
0.099
0.138
again filtered through a dry filter. The action of mercuric chloride varied greatly, especially in the rapidity with which a precipitate formed. For instance, sec-butyl gave a very small precipitate in the same time that n-butyl in the same naphtha gave a heavy precipitate. As a result there was very little removal of sec-butyl but an appreciable loss of the normal. The same happened with isobutyl and isoamyl sulfides. The isoamyl readily gave a heavy precipitate while isobutyl did not. But even with this variation the results show that the lower sulfides are more easily removed than the higher. One surprising variation occurs with allyl sulfide. Allyl sulfide in naphtha 7 or 3 was removed very little by this treatment and much less so than the corresponding normal or isopropyl sulfides. The effect of changing the solvent is the same as with mercuric acetate-there is no appreciable effect with those studied.
80 -
0.105 0.102
0.109
Treatment with Silica Gel
Twenty grams of silica gel were used per 100 cc. of naphtha (7). This was shaken in a shaking machine for 2 hours, allowed to stand to settle, and decanted through a dry filter. The per cent sulfur found in the solution after treatment shows a gradual increase as the sulfur compound added has a longer carbon chain (see Figure 1). More of the secondary propyl and butyl were removed than of the corresponding primaries, but with the amyl there was a very small difference, slightly more of the primary being removed than of the secondary. Slightly more allyl sulfide was removed than the corresponding primary in the same solvent, but the difference was small. Isobutyl and isoamyl were not removed so much as the corresponding normal, but again the difference n-as small. In comparison Youtz and Perkins (7) found, when working with a naphtha solution containing from 0.4 to 0.62 per cent added sulfur, that the actual loss was as follows:
+A SILICA GEL
I NUMBER OF CARBONS IN CHAIN
Figure 1-Per Cent Sulfide Found after Mercuric Acetate or Silica Gel Treatment
Treatment with Mercurous Nitrate
Mercurous nitrate was used as directed by Faragher, Morrell, and Monroe (3). The naphtha was treated with an equal weight of powdered normal mercurous nitrate and shaken 10 to 15 minutes. It was then filtered through a dry filter, washed three times with water, and again filtered through a dry filter before analysis. With this reagent there was an appreciable difference with the various naphthas. Ethyl sulfide was completely removed from naphtha 2. n-Propyl sulfide was completely removed from naphtha 4. The sulfides (n-propyl, allyl, n-butyl, and n-heptyl) and part of the original sulfur in naphtha 3 were completely removed. The blank (naphtha after treatment with mercurous nitrate)
%
Ethyl sulfide Isoamyl sulfide n-Heptyl sulfide
0 279 0 236 0.341
%
n-4-sec-Heptyl sulfide Allyl sulfide Benzyl sulfide
0 191 0 289 0.259
Their results show that n-heptyl sulfide is removed more than any others while the n-4-sec-heptyl is least. It is questionable if their results can be compared with those given in this paper, because (1) there may be a difference in the silica gel used, (2) they have a much higher per cent of added su1fur, and (3) the solvents are different. Treatment of Naphtha 7 with Other Inorganic Reagents
Table I1 gives the per cent sulfur found after treating naphtha 7 containing added sulfides with certain inorganic
March, 1931
INDUSTRIAL AXD ENGIXEERING CHEMISTRY
reagents. The method used was practically the same as described for mercurous nitrate. A known weight of the substance in finely pulverized state was added to the naphtha and shaken in a shaking machine for 15 minutes. The samples were then allowed to settle for 30 minutes or more before decanting through a dry filter. The naphtha after treatment with chromic acid, ferric nitrate, stannous chloride, zinc chloride, and cupric chloride was water-washed and filtered again through a dry filter. The samples were then analyzed by the lamp method. SuLFInEs--Cupric sulfide remored an appreciable amount of the alkyl sulfides tested, zinc sulfide did not. Both sulfides gave a negative test for free sulfur with the doctor solution and secondary amyl mercaptan. OXIDES-Ferrous, cupric, cobaltic (nickel frc.e), nickel, mercuric, lead, and zinc oxides showed a very slight loss. Ferric oxide showed a loss that was more than experimental. Aluminum oxide gave promising results. This compound has been reported very often in connection with patent literature. Chromic oxide also removed some sulfide, but
323
this may be due to oxidation and thin removal by the mater wash that follolyed. Khile these results are not very promising as to the removal of sulfides, it should be remembered that this work was done a t room temperature. Moreover, some of these reagents are fairly efficient in removing mercaptans ( 2 ) and may be of value with other sulfur compounds that have not been studied. Basic copper carbonate and ferric nitrate did not remove the alkyl sulfides studied to any appreciable extent. CHLORIDES-The naphthas containing sulfides after treatment with zinc chloride showed an appreciable loss and less after treatment with stannous chloride or cupric chloride. References Cited (1) (2) (3) (4) (5) (6) (7)
Borgstrom, I A D E ~ G CHEM, 22, 249 (1930). Borgstrom, Dietz, and Reid, I b i d , 22, 245 (1930) Faragher, Morrell, and Monroe, I b r d , 19, 1281(1927) Mabery, A m Chem J , 13, 233 (1891). Thierry, J Chem S o c , 127, 2757 (1925) Wood, Lowy,and Faragher, IND ENG CHEM, 16, 1116 (1924) Youtz and Perkins, I b i d , 19, 1247 (1927)
Removal of Spray Residues from Apples' A Wax-Solvent Method J. R. Nellerz h C R I C V L T U RAL
EXPBRIMEKT ST.4TIOK,
PULLMAS, W A S H .
Hydrochloric acid is a n effective cleaning agent for 08T of t h e a p p l e s coated fruit sufficiently even apples in most cases, b u t i t sometimes fails with grown in the Westwhen an acid temperature of fruits t h a t have been oil-sprayed or t h a t have become ern States must be the highest degree practicable waxy. I t is shown that a thorough cleaning can be washed to remove spray resifrom the standpoint of cost obtained by first dipping t h e apples in certain wax dues before they are marand injury to fruit is used. solvents, preferably methanol, after which a n unheated k e t e d . T h i s is d o n e as It is with fruit of this type hydrochloric acid wash is able t o dissolve and remove soon after h a r v e s t i n g as that the following results were practically all t h e lead arsenate residue. possible, as the difficulty of obtained using a pre-dip waxcleaning increases after the solvent method. fruit has been stored. Oftentimes it is necessary to harvest the Solvents upon Subsequent Cleaning crop quickly to avoid loss from dropping, and in such cases Effect of Various Wax with Hydrochloric Acid the apples must generally lie in storage for a time before Spray residues of lead arsenate are dissolved rather quickly they can be cleaned. Under these conditions varieties such as the Winesap and Arkansas Black, that tend to exude wax, by washing solutions of dilute hydrochloric acid, provided become so coated that it may be very difficult to clean them. the acid can come into contact with the residues. This is The cleaning of waxy fruit may be even more difficult in case not possible, however, if the residues are covered with an inoil sprays have been put on late in the season over a recently soluble layer of wax and oil. The principle of the pre-dip applied spray of lead arsenate. In regions where frequent solvent method is t o dip the apples in a wax-solvent bath bespraying is necessary it is sometimes impossible to aroid the fore passing them into the hydrochloric acid wash. If a formation of a lead arsenate-oil-wax coating on the fruit. sufficient amount of the wax has been dissolved in this bath, In order more thoroughly to clean m-ax- and oil-covered the acid can then remove the lead arsenate residues. Several liquids known to be wax solvents were tried: acefruit, the acid-washing solution is often heated. This is helpful if the solution is kept warm enough to soften the wax tone, diacetone alcohol, methanol, petroleum ether, chlorocoating sufficiently to allow the acid to reach the lead arse- form, and carbon tetrachloride. Preliminary trials only nate. Experiments by Heald, Seller, and Overley ( 1 ) have were made with chloroform and carbon tetrachloride, as shown that a temperature close to 38" C. must be maintained these liquids discolored the apples. One lot of Winesap apples that was subjected to a pre-dip to effect any material softening of the wax. This is often a difficult and costly procedure, as the constantly incoming fruit wsx-solvent study received a calyx spray and five cover sprays frequently has a temperature as low as 10" to 15" C., and even of lead arsenate a t the rate of 3 pounds per 100 gallons of lower if it has been in cold storage. Another difficulty is water. I n addition the last two cover sprays contained 1 the greatly increased rate of corrosion resulting from the per cent of emulsified oil. There was about a week's delay before this fruit could be cleaned, so that a t the time of cleanaction of the warm acid on the cleaning machinery. It has sometimes been impossible to clean wax- and oil- ing with a commercially operating cleaner the surfaces of the * Received October 22, 1930. Published with the approval of the Di- apples were coated with wax. Because of the distinct oily and waxy appearance of this lot of fruit, a part of it was left rector of the Washington Agricultural Experiment Station as Scientific Paper No. 171, College of Agriculture and Experiment Station, State Coluncleaned for experimental work.8
M
lege of Washington. * Present address, University of Florida, Everglades Experiment Station, Belle Glade, Fla
* This fruit was kindly obtained in the Wenatchee district b y F. L. Overley, associate horticulturist of this station.
