Protection of Mechanical Cloth with Phenyl Mercurials J
PETER P. HOPF V u r d , Blenkinsop & Company Etd., London W.1, Englund
EDWARD RACE The tiniuersity, Loeds, England The first Outstanding property of these acids is that, altiiouglt they form salts and complexes of normal formulas which would normally not be expected to be water-soluble, these compounds appear t o dispcise readily. Examination of the solutions wi t l l Tyndall cones reveals that they are colloidal. This is borne out. hy the fact that their stability is adversely affectcd by strong electrolytes and that they can be stabilized by protective lyophilic colloids-e.g., alginates. Thc conception of a pincer moleculc is helpful in understanding t,his reaction; apparently the Fixtan molecule picks up another molecule agid forms a colloidal micell(.. 9 st,oichiometric relationship cannot be estimated, as an excess of the free acid or its sodium salt is necessary t o make a statdc solution. The solubility of the phenyl mercuric compound of tlir. above acid is0.25yo; it rises to 2.5y0when an equal weight of t,lic. free acid or it’s sodium salt is added and to 50yo in 70Yo solution of the free acid in water. A further outstanding property of the Ii’istans is that, d t e r they arc dried on a fiber, they become insoluble and the fibor so treat’edhecomes firmly impregnnt,ed with the substance with wliicli the Fixtan has been brought into combination. This may also be readily explained by regarding t,lie solution as ail ir~eversibl(~ colloid, which, on being dried in contact k i t h a fibrous substance,, loses its electrical charge and cannot again be brought into solut’ion. The following experiinent,s show that. although thcrct is no evidence of reaction between phenyl mercuric Fixtan and wool keratin or cotton cellulose in tlic time needed for fast imprc:grr:itions, the resist’ance t o leaching of phenyl mercuric considerably greater than that of phenyl mercuric acct.ai c. Although it would be expected that the initially insoluble phenyl mercuric acetate is more resistant to leaching than the soluhle phenyl mercuric Fixtan, experiments described later show t ha1. the reverse is true.
h e n , 1 mcrcurials exert strong bactericidal and fungi-
cidal influence even at very low concentrations. Their general use in industry has been retarded by their low solubility and the consequent difficulty of obtaining even applications of sufficient strength on fabrics, and also by the risk of dermatitis involved in handling. These difficulties have been overcome by the production of a phenyl mercuric salt of 2,2’-dinaphthyl methanc-3,3‘disulfonic acid. This salt goes readily into colloidal solution, and the colloid breaks irreversibly when dried on the fiber. Thus it is possible to treat cloth simply and to obtain a fast protection on this cloth. Qualitative and quantitative microbiological tests o n cotton and wool are described for this salt (phenyl mercuric Fixtan) and for phenyl nierciiric acetate.
N liECEiVT years increasing interest lias been shown in phenyl mercurial compounds as industrial fungicides and bactericides, and these compounds have already proved of such outstanding value that indust,i,y has quickly adopted them for the sterilization of liquors and the preservation of timber, textiles, leather, et,c. Their main drawrbaclrs arc their low solubilit’yhence the difficulty of obtaining even applications in high enough concent,ration on fibers and the risk of dermatitis involved in handling some of the compounds. The latter disadvantage is partly offset, however, by the coniparat’ively low concentration in which they arc toxic towards microorganisms. Phenyl mercurials with various anions have been prepared. In general they arc rather low in solubility, and the most iiisoluble ones-e.g., the bromide-are slightly less active than the more soluble ones-e.g., the acetate-when applied to fabrics. An attempt has nor\- been macle to attack the problem from a new anglc. It has been tliaeovered that salts of certain acids although nonsubstant.ive t,o cellulosic or protein [ibera, posscss the property of becoming firmly attached to the fiber when taken up from Rn aqueous solution and subsequently dried. Thercafter, the salts are reasonably fast t o leaching a t neutral and acid p H values and almost completely fast a t allinline pH. These acida have been termcd “Fixtan acids.” They contain at least two sulfonated aromatic rings joined by an aliphatic bridge in such a way that the whole molecule may be regarded as pincershaped, a concept which is helpful in the understanding of the fixing and solubilizing action of such compounds. An example of such a Fistan acid is 2,2’-dinaphthylmcthane3,3’-disulfonic acid:
LEACI-IINC, O F WOOL
Two series of leaching experiments wcrc cari,ied out 011 ivool, one at pH 7.8, the optimum pH value for growth of many proteolytic bac,teria, and the other a t p l l 4.5. Many mechanical woolen cloths-e.g., the \vet felts used on papermaking machines during the manufacture of the higher gradcs of papcr-arp w t r d a t pIl values around 4.5. Loose wool, purified by Soxhlet extract,ion with ether and alcohol follovr-ed by repeated washing with distilled water, wa? impregnated with phenyl rnorcuric Fistari or pure phenyl mercuric acctat,c, t h e initial mercury content in each case being 0.005%, calculatcd on the conditioned xeigl-it of the wool. For pH 7.8 an industrial water was run through the wool a t the rate of 4 liters per hour. For pII 4.5 a sodium hydroxide-potassium hydrogen phthalate buffer solution was siphoned a t the rate of 4 liters per 24 hours through the n-ool held in the tube. Leaching was continued for 16 days, and sunples of wool were removed periodically for estimation of mercui’y content. Figure 1 s h o m the results. In this and subsequcnt experiments, conditioning was carricd out a t 66% relative I-iiimitliiy and 22.2’ C.
Thp phenyl mercuric derivative of this acid is the subjert of this communica tion. a20
INDUSTRIAL AND ENGINEERING CHEMISTRY
April 1949 80
60
C
.I
m
0
i'
ho
20
/-
2
Figure 1.
4 6 8 IO Period of Leryliing, Days
14
16
Except after 5-minute immersion, which apparently is too short a time for equjlibriurn to be reached, the actual absorption of mercury by the wool is approximately equal t o the theoretical value expected by a 100% liquor take-up without chemical combination between reagent and fiber. Coupled with the fact t h a t increasing time of immersion does not result in a n increased mercury content of the yarn, this indicates that there is no reaction between wool keratin and phenyl mercuric Fixtan. This result is somewhat unexpected, as i t appeared likely that the Fixtan molecule would show some substantivity for wool. A further series of tests was therefore carried out in which the time and temperature of impregnation were varied. Table I1 summarizes these tests. All impregnations were carried out at p H 5.6. The tables show that on long immersion or a t elevated temperatures some chemical reaction does occur. This reaction may be the same that occurs on drying after immersion at room temperature for 30 minutes, the method adopted in subsequent impregnations. I t is, however, more likely that the colloidal micelle tends to disintegrate on the surface in time or a t hi.gher temperatures, and thus leave the active chains free to react q i t h the keratin. Normally, however, there is no evidence that this reaction does occur.
Leaching o f Phenyl Mercurials from Wool
A t pH 7.8 Phenyl mercuric Fixtan Phenyl morcuric acetate A t pH 4.5 Phenyl mercuric Fixtan Phenyl mercuric ncetatc
*
I 2
821
-. - --- -*
0 *OX=-
LEACHING OF COTTON
I
X
The leaching of both mercurial~is greater at pH 4.5 than a t 7.8, and a t both pH values the rate of loss of phenyl mercuric Fixtan is considerably lower than that of phenyl mercuric acetate. Thus, after being washed at pH 4.5 for 16 days, the wool impregnated with phenyl mercuric acetate retained an amount equivalent only to 0.001% mercury, whereas that impregnated with phenyl mercuric Fixtan retained an amount equivalent to 0 0023% mercury. Throughout these experiments the following method of analysis was adopted t o determine the mercury content of the fabrics: 1 to 5 grams of the shredded yarn were boiled under . reflux for 2 hours with 40 ml. of a 1 t o 1mixture of concentrated sulfuric and nitric acids. Potassium permanganate was added in small amounts (approximately 0.5 gram at a time) until a permanent excess of manganese dioxide was obtained, and to the solution, cooled t o 0" C., were added 5 ml. of 50% hydroxylamine hydrochloride. The resulting decolorized solution was diluted to 400 ml. and extracted with 5-nil. portions of di-@-naphthylthiocarbazone in chloroform (0.20 mg. per liter) until the last portions showed no color change. The combined chloroform extracts were re-extractgd with 50 ml. of 2.5% sulfuric acid, to which had been added 4 ml. of 1.570 sodium thiosulfate solution. The aqueous layer was refluxed for 10 minutes with 5 ml. of saturated potassium permanganate solution, excess of which was again decolorized cold with hydroxylamine hydrochloride. The solution, diluted to 100 ml., was extracted with di-@-naphthylthiocarbazone in chloroform, the extracts were transferred to a Nessler cylinder, and their mercury contents estimated by colorimetric comparison with standards prepared by extracting in a n identical manner known amounts of a standard solution of mercuric chloride. As the difference in fastness of the mercurials may have been caused by reaction between the wool keratin and the Fixtan, a test for substantivity was carried out: T o test whether reaction occurs between phenyl mercuric Fixtan and wool keratin, 10gram hanks of yarn were worked in solutions of phenyl mercuric Fixtan at pH 4.5 and 7.0 for 5, 15, 30, 60, and 120 minutes. The yarn was squeezed in such a manner as to leave 100% take-up of solution (estimated by weighing), dried a t 50" C., and analyzed for mercury content. Table I1 gives the results.
The leaching tests on cotton consisted of normal exposuie to weathering conditions, since cotton and other cellulosic fabrics are more liable than wool t o be exposed outdoors during their service life. The even exposure t o light, air, wind, and rain of fabrics or of yarn in hank form is difficult to achieve; the exposure tests were therefore carried out by winding yarns on teak frames, in such a way as to give the effect of a very loose fabric in which all parts were equally exposed. The framrs fitted into the slides of a stand, also made of teak ( d ) . Yarn, untreated and treated with phenyl mercuric Fixtan and with pure phenyl mercuric acetate so as to contain O.OliT0 mercury, wa? exposed for 16 weeks, from May 1 to August 21, 1947, the frames faced south-southeast at an angle of 60' t o the horizontal. During the exposure period the rainfall was less than average, although there were a number of heavy thunderstorms arid a great deal of brilliant sunshine. The total amourit of rainfall for the period was 10.05 inches. Every fourth wcek one quarter of the total length of yarn was unwound from each frame for measurement of tensile strength and estimation of mercury content. Figure 2 shows the results. Impregnation of cotton with either phenyl mercurial does not accelerate or retard the photochemical degradation of cotton, the loss in tensile strength curves for ,211 thiee types of yarn being almost superimposed. Phenyl mercuric acetate rapidly leaches out of the fiber, presumably (since the curve for loss of mercury
*
TABLEI. IMPREGTATION OF WOOLWITH PHENYL MERCCRIC FIXTAK pH of Treating
Soh. 4.52 7 04
__ ___
5 min.
0.0027 0.0031
'?o hIrrcury Content after: 15 min. 30 min. 60 min. 0.0041
0 0047
0.0049 0.0044
0 0047 0 0040
120
niin.
0 0043 0 0040
TABLE11. EFFECTOF TIME AKD TEMPERATURE ox ' c T 7 0 0 ~ IXPREGNATION WITH PHENYL MERCURIC FIXTAK I I g r o n t P n t , '70
Hg content, %
Hours of Immer,lon at Room T e m p 2 4 8 16 0 0049 0 0087 0 0082 0 0104 ______ Temp. of Immersion for 30 Min. 1 5 O C. 40' C 60" c. 80C c 0.0047 0,0082 0.0102 0.0117
1 0 0045
INDUSTRIAL AND ENGINEERING CHEMISTRY
822
is smooth) by volatilizatiori as ne11 as by dissolution in rain 15ater during the summer months in an industrial region in England, the pH of rain water is 1.0 t o 5.0. The rate of leaching ot phenyl mercuric Fixtan froiri cotton i i appreciablv slower than
Vol. 41. No. 4
that of phenyl mercuric acet,ate; after 16-week exposure, only 7% of the initial amount of mercury remained on the fiber treated with phenyl mercuric acetate, and 30YGremained on that treated wit,h phenyl mercuric Fixtan. This fact is very important in the treatment of cotton fahrics which, during the life, undergo outdoor exposure. The behavior of merc cotton exposed in tropical and subtropical regions, whew t l i ~ temperature and p H of rain are higher and the sunlight i t,lian in industrial arcas in England, canriot hit accurately forcw,st from the exposure results reported here. However,, I h : data stroiigly suggest that the volatilit,y and leacliabilitp in rain w a k r of phenyl mercuric Fixtan are considerably less than those of plimyl mercuric Bcetrtte, and, thcwfore, that a toxic concctitration of phenyl mercuric Fist an would remain on the exposed material for a much longer period than would a tosic coiicentration of phenyl rnercuric acet,ate. This behavior on cotton cannot be explained by a rcwtion between cellulose and Fixtan, as shown by a test carried out in a manner similar t o t h a t described for. wool (Table 111). Table IV sliows that even high temperatures and prolonged time do rioL increase the concentration on cotton fiher. I t is apparent that impregnation for 15 t o 30 minutes is necessary for equilibrium b e t m e n solution and fiber to he reached. The results show 1 1 0 evidence of suk)stantivily between phenyl mercuric Fixtan :tnti cellulose. t ' E N K l ~ A T I O N O F FIXTANS
n
6
4
/
/
!G
4
TABLE 111.
/ / 1
Treating: p H '>f Soh.
8
lZ
I 6
Period of Exposure, IVeeks
Tensile Strength and Leaching Rate of Phenyl lkaercurials after Exposure 0 -. Untreated -. Phenyl mercuric Fixtan 0 Phenyl mercuric acetate 0
-
-- -- -- - - -- - -
IRIPREGX.4TION O F COTTON WITH P H E N Y L ;\rlGRCZ.RIC
FIXTAS cy, l l e r c u r p Content a f t e r : 1: inin. 30 min. 60 min. 0.010 0.013 0.0092 0.014 0.0098 0,011
6 min. 0.0063
4.50 7 08
4
Figure 2.
:\lt,hough this property has no direct bearing on the tw;&tiiwiit of wool or cotton, the Fixt,ans have remarkable pov-er of penetration. Most disulfonic acids exhibiting t,his propert>yare syntari acids (synt,hetic t'anning agents); but in gcneral tanning properties are in relation neither t o the solubilizing, fixing, nor penetrating effect, although t o some extent tanning properties could explain penetration. Under equal pressure phony1 mercuric Fixtan penetrates tjimher roughly 1.5 times as far as water and 2.8 times as far as creosote. Cuttings from unseasoned Douglas fir were immersed ITith t,heir ends sealed in creosote, water, and a 0.01% solution of phenyl mercuric Fixtaii and subjected t o a pressure of 20 pounds per square inch. After 15 minutes t,he average penetration for creosote was 1 mni. and for water, 1.8 mm.; mercury could be detected in the last cutting by means of diphenylcnrbazide indicator to an average depth of 2.8 mm. A lYGsolution of the silver-salt of Fixtan T T ~ Sfound t o penetrate living human tissue t o a depth of 3 mm. This penet,rative power is closely related to pH; it is least a t alkaline and neutral pH values, increases to a maximum a t pH 2.5, and decreases again a t still lower p H values. This property, therefore, is not the same as ordinary tanning a.ction, as the tanning properties of syntan acids increase in direct probortion to decreasing pEI values.
0,0081
~~-
I 2 0 inin.
0.0098 0.013
TABLEIV. EFFECTO F TIMEASD TERIPERATURE ON C o , r ~ o ~ I~IPRECXATION wrr~ PIIEKYL MERCURIC FIXTAN Hottrs of Iriirnersion at R oom Temp I l r contcnt,
cia
1
1
4
8
0.012
0.01.5
0.011
0.012
~e:111>.of Irrimersion for 30 hIin. _--___-
1:.
Hi: content,
c.
0.0096
c.
400 (2.
600
0.010
0.Olt5
1(i 0,OItj 800
c.
0.011
*
April 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
If the phenyl mercuric Eixtans combine the fungicidal and bactericidal activities of phenyl mercuric compounds with the Fixtan properties, they can be used to advantage in the sterilization of industrial fabrics and othei fibrous materials which are continually subjected to contact with liquors carrying degradative microorganisms or which have to withstand exposure to air-, watei -, and soil-borne microorganisms under stringent climatic conditions. Therefore, the bactericidal and fungicidal activities of phenyl mercuric Fixtan on wool and cotton were investigated as prototypes of protein and cellulosic fibers; comparative experiments were conducted with phenyl mercuric acetate. Owing to the low solubility of phenyl mercuric acetate, it is not possible to obtain a high enough concentration on the fabric in one application from aqueous solution. I t was necessary to soak the fabric in a concentrated solution of phenyl mercuric acetate, express, and repeat the procedure until the desired concentration was obtained. As the phenyl mercuric Fixtan take-up of the fabric is known, the desired concentration could be obtained in one application from a solution made up to known strength. In these tests th6 mercurial on the fiber mas estimated as described above. This method may sometimes lead to erroneous conclusions, as some of the mercury may have combined directly with the SH groups of the keratin. This cystine-combined inerw r y is chemically and biologically inactive, and the analytical result alone, therefore, is not always proof of impregnation especially after treatment with organic mercurials. Cystinecombined mercury may be detected by measuring the increase in resistance to extension of individual wool fibers. Wool treated with phenyl mercuric Fixtan or phenyl mercuric acetate gave no evidence for the assumption of the presence of inactive mercury. I n the case of reduced wool some slight increase in resistance t o extension was found with phenyl mercuric acetate,
c
$ 6C
c
m
2C
823
but this may also have been due to the combination of SH groups with the phenyl mercuric radical rather than with mercury itself. BACTERICIDAL EFFICIENCY ON WOOL
Unreliable results may be obtained with mixed cultures of proteolytic bacteria. Therefore, to test, qualitatively the bactericidal activity of phenyl mercuric Fixtan, six species of t h e most virulent wool-decomposing organisms were used separately. These organisms are prolific in nature and have been identified in cultures obtained from prematurely degraded mechanical cloths: Pseudomonas Jluorescens, Ps. pyocyanea, Proteus vulgaris, Bacillus mycoides, B. mesentericus, and B. subtilis. New Zealand Romney wool, taken from the belly of a fleece, w~bspurified by Soxhlet extraction with ether and alcohol, and sterilized by immersion in boiling water for 15 minutes on three successive days. Immediately after the final sterilization, 10gram samples of the wool were treated in a solution of either phenyl mercuric Fixtan or pure crystjalline phenyl mercuric acetate; the concentrations and wringing pressures were adjusted to give wools with various mercury contents. From a series of twelve samples each of Fixtan-treated and acetate-treat,ed wools, four samples were selected in which the mercury contents were 0.0005, 0.001, 0.005, and O.Ol%, respectively, on the weight of conditional wool. The various species of proteolytic bacteria were separately incubated in 2-ounce glass jars in the presence of 40 ml. of a dilute nutrient broth (2 grams of peptone, 1 gram of sodium chloride, 1 gram of extract per liter) and buffered to p H 7.8. When the concentration of viable organisms had increased to approximately 1000 per ml., 1 gram of wool was introduced. Incubation was continued 1 , 2, or 3 days for untreated wool, and 10 days for wool cont,aining O.oOp5 and O . O O l ~ o mercury. The incubation period for wool containing 0.005 and 0.01% mercury was 20 days, and the jars were reinoculat'ed with their respective organisms after 10 days. A t the end of each incubation period fibers were examined under the microscope. From the examination of t,wenty to thirty separate fields in each case, the proteolytic activities of the species were classified as extensive, medium, slight, very slight, or inhibited. Table V gives the results. Under t h o stringent conditions of the test, it is apparent that even as little as 0.000570 mercury has an appreciable delaying action on t,he bacterial attack of the wool. Thus, degradation by R. subtilis of wool containing 0.0005% mercury as phenyl mercuric Fixtan is approximately the same after 10 days as that of untreated wool after 1 day. For t,hc other organisms tested, degradation after 10 days of the wool containing 0.0005% mercury is considerably less than that of the u?treated wool after 1, 2, or 3 days. In general, especially a t the lowest concentration of mercury, phenyl mercuric Fixtan appears to have slightly lower bactericidal activity than phenvi mercuric acetate; a t t,he higher conceni4 I B 42 S6 70 84 trations there is a striking similarity in l'eried of Incubation, Days bactericidal efficiency, suggesting that the toxicit,y of the phenyl mercuric Figure 3. Bactericidal Efficiency on Wool (Quantitative Tests) radical is largely independent of the Untreated . 0 ' anion. Phenyl mercuric Fixtan 0.0005 Hg 0O.OOl%o Hg X The inhibitive action of the phenyl 0.01% Hg 0 Phenyl mercuric acetate 0.0005% H g 0 mercurials varies with the species of 0.001%~H g X organism, the order of decreasing proteo0.01% Hg 0
-- --
------ ----------- -- -- -- --
.
'
INDUSTRIAL AND ENGINEERING CHEMISTRY
824
Wool ireated with phenyl mercuric Fixtan; Bacillrm srtbt i l i s , 84 days
Untreated
wool; Bacillus s t , b t i l i s , 4.2 days
Figure 4.
sewed to glass Tvicks t)y.glass throad and suspciitlod from the lids of large jars, were inoculated by spraying with a suspension of €3. subtilis ( 5 nil. containing approsiniately 1000 organisins per mi. ) ; cacli jar, Trith yarn and glass wicks iti position, and coiitaining 1 inch of sterilizcd dilute Iiutric3rit medium, was incubated at 30" C. To renioTx toxic products oi metabolism, cveIy sovrvith (lay the nutricrit nicdium as renewvcrl, and tlic yarns were removed and n-aslied from 6 jet Lvith tlilute nutrient medium (200 ml. per. hank); thc ratc of degradation of the unprooied ~ o o shonctl l that this treatment. did not aff'ect tlie activity of t h e bacteria within the fibers. T o cnsurc that viable organisms TLalways presciit on the proofed yarns, lianlrs the latter vwc: rcirioculatcd v-ith thc bacterial suspension ( 2 ml. per hank) every fourteenth day. Ynrris untroatc:d and h a t e d with phenyl mercuric Fixturi atid 1)ure phenyl mercuric acetate werc tcstctl in this w ~ y . The proofed yarns contaiiied 0.0005, 0.001, or 0.03 % mercui.y (calculat,ed on the contfitioiic-tl \\eight of the vmol). Tncubation was contiiiucd for 84 d a y ; samples were removed periodically, washed gentlv but efficiently with distilled natcr, dried at. 40" C., and condilionctl Iwiore tonsil(: strength \\-as detcrmincd. The data shown on Figure 3 \vert calculated from an avcrage of fifty t o sixty brcaliirig strength detcrminations. Esariiinatiori of the incubutctl varris under the microscope, together with st,aiiiing tests \T ith niet,liylene blue and bcnzopurpurin, iiidicat,ed that Ihc slight ion.: in strength of yarn containing 0.0170mcwury r ~ a sCBU
Wool treated w i t h Untrontcd wool; phenyl mercuric horse dung funxi, Fixtan; horse dung 28 date fungi, 84 days
Berlcefeld Filter Candle Tests
lytic activit,y on tlie proofed I\-ool Iwiiig as follows: B . subtilis, P. r?r/yuris, H. mesentericus, Ps. $?iorescens, Ps. ~ > J O U J m e a , B. mycoides. For complctc illhibition of degradation by B . siibtilis undrr the conditions of t h e test, \io01 rcquires a mercury content of more than 0.005%; the activity of the o1hi:r organisms tested is virt,uallJ- inhit)itcd a t a niercury content of 0.00570. 111 pmctico, conditions of proteolytic. dcgraciatiom will rarely, if ever, approach the optimum of the lal~orrttory test; a n amount of phenyl mcrcurjc Fixtan equivalent to 0.003 t o 0.004y0 mercury on the weight of the wool n.ill probably inhibit bacterial degradation of the f i l ~ t r . The qualitative test just describd \vas supplemented ti? a quantitativt, assay of bactericidal activit,y. Sirigl(:fold wool yarn (375 grains per 50 yards) was used, since the variations in dcgrcc: of attack t.o individual fiber6 n-ercx too wide t o permit single fiber measu1,ririenta. Moist heat sterilization tcndt:d to damage the wool slight,ly, and yarn which hrld h e n Soxhlet-extracted with cthfir arid alcohol and then washed in six c h m g c s of sterile glass-distilled xvater \vas t,hercfore used. B . s l ~ b t i l i sn-as selcctecl as being the most mercury-tolcraiit organism, and the method was similar to tllat described by Race (1). Hanks of )-aril,
Vol. 41, No. 4
I
I
/ 28
14
42
56
Period of Incubation, U&ys
Figure 5 .
- -.
Fungicidal Efficiency on Wool
-
-X0-----0 ----------x0- -0 - --- --- -
Lntreated - . 0 I%m> I mercuric Fixtan 0.0005' q IIg
0 . 0 0 1 % Hg 0 a 005 W Hg PhentI mercuric acetate 0.000570 Hg 0.001% ~g 0.005VoHng-
n4
April 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
P
Ioc
80
/6
i", c
:: 40
s
I 20
56
42 Period of Incubation, Days
Figure 6.
io
Fungicidal Efficiency on Cotton (Quantitative Tests)
- - -- -
Untreated * Phenyl mercuric a x t a n 0,0001 % Hg 0.0002 % H g 0 . 0 0 0 5 % Hg 0 001 yo Hg Phenyl mercuric acetate 0 . 0 0 0 l y ~Hg 0.0002q0 Hg 0 . 0 0 0 5 % Hg 0,OOlY'Hge
--
---
-0 ------ -- -- -- o -------------- 0- ---------0
X
84
825
I n this way the wool, although kept in an atmosphere a t 100% relative humidity, had a regain of only about 30% a t equilibrium. After incubation a t 25" C. for 84 days, proteolysis appeared to be confined exclusively to fungal attack. Candles were removed periodically; the wool was washed gently but thoroughly with distilled water, dried a t 40" C., and conditioned before tensile strength was determined. Figure 5 shows the results. A general white mycelium appeared on the untreated yarn after 24-hour incubation, but not until after 30 days mas any growth visible to the naked eye on the yarn containing 0.0005% mercury. No visible growth, either microscopic or macroscopic, appeared on yarn containing 0.001 or 0.005qlo mercury during the 84-day incubation. Therefore, inhibition of fungal attack on wool occurs a t a lower concentration of mercury than that required for inhibition of bacterial attack. The fungicidal efficiency of phenyl mercuric Fixtan and pure phenyl mercuric acetate was the same; less than 0.001% mercury was adequate t o prevent fungal growth under optimum conditions.
0
X
0
lytic fission of cross linkages b(3tween the peptide chains of the fibers rather than by bacterial proteolysis. The yarns with lower mercury content gave visual evidence of bacterial attack under the microscope. Degradation of wool under the conditions of the quantitative tests a-as considerably slower than in the qualitative tests. The later results indicate: ( a ) For complete inhibition of attack by B. subtilis, a n amount of phenyl mercuric Fixtan (or of phenyl mercuric acetate) equivalent to a t least 0.005% mercury on the weight of the fiber is required when conditions approach optimum for bacterial proteolysis. ( b ) The bactericidal activity of phenyl mercuric Fixtan is slightly less than that of pure phenyl mercuric acetate a t the lowest concentrations of mercury and equal to that of pure phenyl mercuric acetate a t the highest concentrations of mercury. FUNGICIDAL EFFICIENCY ON WOOL
Horse dung was used as inoculum in quantitative assays of fungicidal efficiency. It was harvested from a field and freed from partially digested vegetable matter by filtering a n aqueous sludge through coarse muslin. T o prevent attack by the proteolytic bacteria in horse dung, the lower p H and temperature ranges of proteolytic fungi were utilized. Large Berkefeld filter candles (10 X 2 inches) were coated with the aqueous sludge of horse dung, which had been adjusted to p H 5.5, and were then partially dried by storage a t 37' C. for 48 hours (Figure 4). Yarns, untreated and treated with phenyl mercuric Fixtan and with pure phenyl mercuric acetate so as to contain 0.0005, O.OOl%, or 0.005% mercury on the conditioned weight, were air-dried and wound on the candles; four candles were used for each type of yarn. The level of water in the filter jackets was maintained a t 0.25 inch-that is, below the top of the metal cap of the candle.
FUNGICIDAL EFFICIEIVCY ON COTTON
SINGLE PURE CULTURE TEST. Qualitative tests indicated that the concentration of phenyl . - niercuric Fixtan required for inhibition of attack of cotton by cellulose-decomposing fungi is lower than that required for inhibition of attack of wool by proteolytic organisms. Cotton yarn (24/3s) was thoroughly scoured with soap and sodium carbonate and washed to neutrality in distilled water. Ten-gram hanks were treated with various solutions of phenyl mercuric Fixtan or phenyl mercuric acetate (both a t p H 5.8) so that they contained 0.0001, 0.0002, 0.0005, or 0.001% mcrcury, calculated on the conditioned weight of the cotton. Chuetomium globosum, a prolific and active cellulose-decomposing fungus, was the test organism. The inoculum was prepared by adding sterilized glass beads to a young, actively sporulating culture of the fungus in weak malt-agar in a sterilized flask and shaking vigorously until a uniform suspension of spores was obtained. An aliquot (5 ml.) of the inoculum was transferred by spraying from a small atomizer to each hank of yarn. Wicks of glass tape were sewed to each hank t o absorb a culture medium of dipotassium hydrogen phosphate, magnesium sulfate ammonium nitrate, and sodium chloride contained in large glass jars. The inoculated hanks were suspended from glass hooks in the lids of the jars which were incubated a t 28' C. After 2-day incubation, a sporulating mycelium was visible on the unproofed hanks, and by the twenty-fifth day they had fallen in almost complete disintegration from their hooks. The treated yarns were reinoculated with spores of the fungus every tenth day, and a slight growth was visible on yarns containing 0.0001yo mercury toward the end of the second week of incubation; this growth spread rapidly and covered the whole of the cotton before the end of the incubation period. Sparse colonies of fungal growth developed on yarns containing 0.0002% mercury during the sixth week, but they were extremely slow in developing. No visible growth occurred on yarns containing 0.0005 and O . O O l ~ o mer-
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
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T h e results given in Table V1 suggest that, although it is possible t o inhibit growth of cellulose-decomposing organiqms by concentrations of phenyl mercurial only slightly in excess of 0.00057Gmercury, certain species which do not decompose cellulose are more mercury tolerant. A . niger and P. brezz-conpacturn w r c inore prevalent on the incubated yarns containing 0.005 and 0.01yGmercury. Independent qualitative tests showed that A . rtiger, under optimum conditions of temperature, humidity, and nutritive requirements, developed slomly on cotton impregnated u i t h either phenyl mercuric acetate or phenyl mercuric Fixtan in a concentration equivalent to 0.017% mercury, and P . brevi-cornp a c t u m produced sparse green colonies on cotton impregnated with either mercurial in a concentration equivalent to 0.012% mercury. Seither fungus degraded the cellulose, even after incubation for 12 weeks, and neither fungxs developed on cotton impregnated a i t h 0.02% mercury FILTER CANDLE TESTS ON COTTON
01113' in rare instances are cellulosic materials subject to corn-
Period of Incubation, Days
Figure 7 . Bactericidal Efficiency on Cotton (Quantitative Tests) Untreated 0 * Phenyl mercuric Fixtan OaOOl% Hg 0
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----0 ----c --------------T;Preatedwith phenyl mercuric Fixtan is free from risks. "LITERATURE CITED
(1) Race, in "Symposium on Fibrous Proteins," Soo. of Dyers and Colourists, p. 80 (1946). . (2) Race and Rome, J . Soc. Dyers Colourists, 62,19 (1946). RECEIVED February 1, 1948.
Pyrolysis of 2-Pentene and Trimethvlethvlene J
H. J. HEPP AND F. E. FREY
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Phillips Petroleum Company, Bartlesuille, Okla.
Trimethylethylene and 2-pentene were cracked in quartz by a flow method at temperatures in the range 778' t o 850" C. in the presence of varying amounts of steam. Butadiene was the major product from 2-pentene, the yield ranging from .33 to 55 moles per 100 moles of 2pentene reacted, depending upon conversion, temperature, and dilution. Pentadiene was also formed in amounts of the order of 10 moles per 100 moles reacted. Ethane and butene appeared to be primary reaction products along with butadiene, ethylene, and propylene. Isoprene was the major product from trimethylethylene, the best yield obtained being 38.3 moles per 100 moles reacted. Butadiene yields of approximately 10 moles per 100 moles reacted were also obtained. Butylenes were formed in substantial amounts of the order of 40 moles.
T
HE pyrolytic reactions of the amylenes are of interest both
from the standpoint of reaction mechanism studies and diolefin production. Diolefin yields are favored by high temperature, and with the notable exception of the work of Gorin et al., temperatures employed by previous investigators were too low for maximum diolefin yields. Norris and Reuter (7') pyrolyzed 2-pentene and trimethylethylene a t 575 " to 650" C. and found trimethylebhylene to be substantially more stable than 2-pentene. Subsequent investigators have confirmed this finding. 2-Pentene yielded approximately 12% by weight of butadiene and approximately the same
,amount of butenes. Trimethylethylene yielded isobutylene, but butadiene was not found. Mikhailov and Arbuzov ( 5 )pyrolyzed 2-pentene in the presence of steam a t 550" and 700" C., and obtained butadiene yields as high as 15.6%. Recently Gorin, Oblad, and Schmuck ( 2 ) reported butadiene yields of 50 to 55 moles per 100 moles of 2-pentene reacted, and isoprene yields of 42 to 54 moles per 100 moles of trimethylethylene reacted, by pyrolyzing the amylenes a t 800' C. in the presence of sufficient nitrogen to reduce the partial pressure to 0.1 t o 0.2 atmosphere. The present investigation was undertaken t o determine the influence of high temperature and pressures in the range 1 t o 0.1 atmosphere on the pyrolysis products, and t o obtain kinetic data. APPARATUS AND PROCEDURE
Figure 1 is a diagram of the apparatus. Because of the short heating times employed, i t was considered impractical to use a tube furnace. Accordingly, a salt bath was constructed. A 9-inch length of 3-inch pipe was used as a container for the salt and was heated by a coil of Chromel resistance wire wrap ed about a close-fitting alundum core contained in a housing filed with Sil-0-Cel. The salt bath container projected about 2 inches above the housing in order t o prevent migration of salt into the Chromel windings. The reaction coils were made of 2-3 foot lengths of 1 t o 2-inm. i.d. quartz tubing. This tubing was formed into a coil and immersed to a depth of 5 inches in the salt bath. Sodium chioride alone or mixtures of equal quantities of sodium and
