US3852174A - Hydrophobic coatings and synthesis by electrochemical reduction of sulfonium compounds - Google Patents

Abstract

Nonpolymeric hydrophobic coatings are applied to solid electroconductive articles used as cathodes in an electrolysis system by subjecting a solution of a sulfonium salt in a predominantly aqueous electrolysis solvent to an electrical potential sufficient to reduce the sulfonium salt. Water is the preferred solvent. In example, iron is coated with a grease by the electrochemical reduction of p-dodecylbenzyldimethylsulfonium chloride in aqueous solution at a cathode potential (reducing potential) of -1.0 volts versus a standard calomel electrode; the grease being a mixture of p,p''-bis(dodecyl)bibenzyl and pdodecyltoluene.

Description

United States Patent [191 Settineri et al.

[ Dec. 3, 1974 [75] Inventors: William J. Settineri; Ritchie A.

Wessling, both of Midland, Mich.

[73] Assignee: The Dow Chemical Company,

Midland, Mich.

[22] Filed: Sept. 26, 1972 2 11 Appl. No.: 292,292

Related US Application Data [63] Continuation-impart of Serv No. 879,511, Nov. 24, 1969, abandoned, which is a continuation-in-part of Ser. Nos. 647,895, June 22, 1967, Pat. No. 3,480,525, and Ser. No. 647,896, June 22, 1967, Pat.

[52] US. Cl 204/73 R [51] Int. Cl. C07b 19/06, BOlk 1/00, C231 7/00 [58] Field of Search 204/73 R [56] References Cited UNITED STATES PATENTS 3,480,527 11/1969 Wessling et a1. 204/73 R Settineri et a1. 204/72 Wessling et a1 204/72 Primary ExaminerF. C. Edmundson Attorney, Agent, or Firm-L. Wayne White ABSTRACT Nonpolymeric hydrophobic coatings are applied to solid electroconductive articles used as cathodes in an electrolysis system by subjecting a solution of a sulfonium salt in a predominantly aqueous electrolysis solvent to an electrical potential sufficient to reduce the sulfonium salt. Water is the preferred solvent. ln example, iron is coated with a grease by the electrochemical reduction of p-dodecylbenzyldimethylsulfonium chloride in aqueous solution at a cathode potential (reducing potential) of 1.0 volts versus a standard calomel electrode; the grease being a mixture of p,p-bis(dodecyl)bibenzyl and p-dodecyltoluene.

26 Claims, No Drawings HYDROPHOBIC COATINGS AND SYNTHESIS BY ELECTROCHEMICAL REDUCTION OF SULFONIUM COMPOUNDS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of our copending U.S. Pat. Application, Ser. No. 879,511 filed Nov. 24, 1969, now abandoned which in turn is a continuation-in-part of our copending U.S. Patent Applications, Ser. Nos. 647,895 and 647,896, filed June 22, 1967, now U.S. Pat. Nos. 3,480,525 and 3,480,527, respectively.

BACKGROUND OF THE INVENTION Polarography is a well established means of quantitatively identifying various electroreducible components in a mixture, such as the identification of each metal in a mixture of metal salts. See, for example, Polarographic Techniques, by L. Meites, 2nd Ed., John Wiley and Sons, Inc. (1965).

Analytical polarographic techniques generally require a mercury or platinum cathode, mercury electrodes being by far the most common, and extremely well controlled electrical potentials. See L. Meites, Controlled-Potential Electrolysis in A. Weissberger, Editor, Technique of Organic Chemistry, Vol. 1, 3rd Edition (lnterscience, N.Y., 1959 pp. 3281-3333, for a general summary.

The polarography of certain sulfonium s'alts is described by Colichman and Love, J. Org. Chem., 18, 40 (1953). However, the production of any useful material by the electroreduction of sulfonium salts was unknown until we discovered that p,p-dinitrobibenzyl compounds and poly(p-xylylene) could be-prepared by the electrochemical reduction of the appropriate sulfonium salts, described in our copending patent applica tions Ser. Nos. 647,896 and 647,895, which are now U.S. Pat. Nos. 3,480,527 and 3,480,525, respectively.

SUMMARY OF THE INVENTION This invention pertains to our further discoveries regarding the electrochemical reduction of organic sulfonium salts; said reduction requiring an electrolysis system comprising an anode, a cathode, an electrolysis solvent and a means for establishing and maintaining an electrical potential between said anode and cathode.

It has now been discovered that solid electroconductive articles can be easily coated with a uniform hydrophobic coating by using such electroconductive articles as the cathode in the above-described electrolysis system and subjecting a solution of an organic monosulfonium salt and an electrolysis solvent to an electrical potential sufficient to reduce said sulfonium salt. Thewear-resistant coating, or one can apply a decorative and/or colored coating to various articles (color being imparted by a chromophore(s) in the product), and other like uses. The major import of this aspect of the subject invention resides in coating metals, particularly iron and copper and their alloys with a protective and- /or lubricating coating by electrochemically reducing a sulfonium salt from an aqueous solution.

Another important aspect of this invention is that the coatings thus produced are due to and accompanied by the one-step electrochemical synthesis of many useful compounds. Such compounds may be recovered from the reaction mixture by washing the cathode with an appropriate solvent, scraping or wiping the cathode, by choosing an electrolysis solvent which dissolves both the sulfonium reactant and the product(s) thus produced or by any other convenient method.

Generally, the coating is a mixture of compounds. E.g., the electrolysis of benzyldimethylsulfonium chloride in aqueous solution produces (a) bibenzyl, (b) toluene and (c) dimethylsulfide. The product distribution of (a) to (b) within the mixture can be varied by the choice of sulfonium salt(s) and process conditions.

The electrochemical preparation of p,pdinitrobibenzyl compounds from p-nitrobenzyl sulfonium salts was described in our copending application (Ser. No. 647,896), which illustrates the coupling reaction. The synthesis was conducted in an aqueous or polar organic solvent using mercury, platinum or copper and other electroconductive materials, such as graphite, as the cathode.

The dimerization of p-nitrobenzyl sulfonium salts is facilitated by the p-nitro substituent group which has a relatively high Hammett 0' constant reflecting a high I (r values of the substituent groups. But, in view of the relation shown by Streitweiser, it was not surprising to discover that benzylic sulfonium salt did not follow such a reasonably linear relationship and that benzylic sulfonium salts bearing para-substituents having a relatively low or even negative 0 value, such as dodecyl, could be electrochemically reduced and undergo a corresponding coupling reaction at surprisingly low cathode potentials (reducing potentials) in corresponding solvents (particularly water). From'Streitweiser, one would have predicted that benzylic sulfonium salts having substituents with a low or negative oconst'ant would have required much higher cathode potentials, i.e., increasingly negative voltages, than was actually observed and in those instances where the substituent had a 0' constant as negative as dodecyl, for example, the electrolytic decomposition of water would have been expected on cathodes having a low hydrogen overvolt- 1 age, such as platinum. This was not observed to any substantial degree. A similar case of reduction is experienced for other sulfonium salts as described herein The'cathode may suitably be any article which is solid and electroconductive and may be metallic or nonmetallic in nature. Illustrative of suitable cathodes are (a) articles of metals having a hydrogen overvoltage less than mercury, such as those having a relatively low hydrogen overvoltage (e.g., iron, nickel and platinum) and those having a relatively high hydrogen overvoltage (e.g.,.lead, copper and tin), and metal alloys, such as steel, brass, and the like, and articles bearing a conductive metal coating, such as chromeor copperplated iron or steel articles, aluminumor chromeplated plastic articles, and the like, and (b) nonmetallic articles, made from carbon, graphite and the like and other electrical semiconductors, such as gallium, germanium, and the like. It is known that most metals are electroconductive and have a resistivity of less than about ohm-cm. at 300 K. and that most electrical semiconductors have a resistivity of less than about 10 ohm-cm. at 300 K. Conductor metals are the preferred class of materialsto be coated, particularly iron, copper, nickel, aluminum, tin, zinc, lead and alloys thereof, based on the extensive commercial use of such metals. The most preferred metals being iron, copper or alloys of iron or copper.

The shape and size of the article to be coated is relatively unimportant. E.g., needles, razor blades, transistors, diodes, tubes, wire, barrels, car bodies, pipelines, etc.', on up to a slab of rolled metal can be coated by the subject process. This fact makes the invention particularly useful since there -is a tremendous need for protective coatings, and a method of applying same, on articles which are subject to oxidation and degradation when exposed to the atmosphere, such as an unpainted car body, particularly temporary coatings which can be easily removed with a solvent. The process may be used to apply insulating coatings to electrical wire and parts. The subject process may be used to coat rough surfaces as well as smooth, although for practical reasons, smooth regular surfaces are preferred when the purpose is to prepare and recover the electrolysis product. B. THE SULFONIUM SALTS Suitable sulfonium salts have the formula ia a? n-C H wherein R R and R are hydrocarbon 0r hydroxy. halo-, nitroor cyano-substituted hydrocarbon groups having up to about 30 carbon atoms or more and are limited only by the solubility of the sulfonium salt in the electrolysis solvent, and A is an electrolytically acceptable anion, such as an anion of an inorganic or organic acid. Preferred salts are those wherein R and R are lower alkyl or hydroxy-alkyl of 1' to about 10 carbon atoms and R is an activated group; by activated" we mean a group having a methylene. carbon attached to the sulfonium sulfur and which is activated by being attached to an aromatic nucleus, a carbonyl group, an olefin or other like groups. Preferred R groups therefore include a benzyl group having the formula (v) CH2 wherein R is a hydrocarbon group, such as alkyl, aryl, aralkyl, alkaryl, cycloaliphatic alkenyl or a corresponding halo-substituted hydrocarbon group and n is an integer 0 to 5. Most preferably, R and R are alkyl groups of one to about four carbon atoms and R is a benzyl group having the formula 'wherein R is hydrogen, alkyl (particularly alkyl of 4 to 18 carbon atoms) or alkenyl (particularly vinyl or allyl); an allyl group (CH #IHCH an ester or amide group wherein R is alkyl, aryl, etc.) and other like groups. Examples of suitable such sulfonium salts include those of the Formula IV wherein:

Table I a a CH CH C1 n-cglt n-CnH Br 0 5 C H Br n-.G1;H OH n-QuH OH F can on c n on c1 ri -emu? M 311 (:1 CH CH atzggyl CH C 11 N0 Table I Continued cH (-ca SQ on Dian -O c a swa 3 or s-c a and the like As above, the electrolysis process-results in a mixture of products which may be represented by R R R -H and R -SR (R naturally could be replaced 5 with R and R If R, through R are each low molecular weight groups (one to about five carbon atoms), then the product is generally a mixture of gases or liquids having a specific gravity less than one-hence,

such sulfonium salts are not particularly useful in ap- I plying a protective or lubricating coating per se, but they are operable in the process for synthesizing certain compounds. Furthermore, the volatility of the R S-R by-product when R and R are of low molecular weights can be used to advantage when a sulfide is not desirable in the end product; and the converse when R SR is a desirable component, such as tolylnte (cHFcm-cu-r cH 'hs which is hydrophobic and can be subsequently cured to give a hard coating.

C. THE SOLVENT Suitable electrolysis solvents are compounds which dissolve the sulfonium salts and are inert to the product formed. Suitable solvents therefore include water,

polar organic solvents, such as tetrahydrofuran, dimethylformamide, dioxane, acetonitrile, propionitrile, dimethylsulfoxide, hexamethyl phosphoramide, lower alkanols, such as methanol, ethanol, isopropanol and 'butanol, organic acids, mixtures of the above organic solvents, mixtures of the above organic solvents and water, and the like. Preferred solvents when a coating is desired are those which dissolve the salt but which do not dissolve, delaminate or otherwise adversely affect the coating formed; such solvents arepredominantly water. Water is the most preferred solvent in coating applications, said preference being based on' its excellent solvating properties for most sulfonium salts (and supporting electrolytes, if used), its ready availability, ease of handling, etc.

D. VOLTAGE The voltage and current requirement through the electrolytic media depend on the particular sulfonium salt to be reduced; however, any voltage and amperage sufficient to reduce said salt is suitable so long as the electrolysis solvent is not correspondingly or preferentially reduced since degradation of the solvent may cause irregularities in the desired hydrophobic coating. Voltage levels which reduce both the sulfonium salt and solvent are operable but not preferred. The electrical potential (reducing voltage) may be applied and maintained at a constant value by continuously decreasing the applied voltage, as described by Meites above, or a potential may be supplied from a constant energy source, such as a battery. In the latter instance,

the measured electrical potential at the cathode would decrease to a more negative value as the cathode is coated. Both methods of applying the electrical potential have many advantages, however, we currently prefer the controlled voltage technique since little, if any, gassing is generally observed. E. SUPPORTING ELECTROLYTES The subject process may optionally include a supporting electrolyte, such as salts of strong acids, in the electrolysis solvent media. Examples of such supporting electrolytes include NaCl, KCl, NaNO Na- SO and the like. The use of such salts does not hinder the formation of the desired coating so long as the electrical potential is insufficient to reduce the metal cations. Use of such salts may be advantageous in assisting'the flow of current through the reaction mixture and thereby hasten the desired reaction. However, the use of supporting electrolytes is not required and is undesirable when the supporting electrolyte may corrode the electrode. E.g., KCl entrained in the coating of steel article may eventually cause corrosion. .ELQED ERA PROCESS NDIT QNS The subject process may be conducted as a batch or continuous process, i.e., the electrolyte media, comprising an electrolysis solvent and organic sulfonium salt, may be continuously rejuvenated by adding in (a) more sulfonium salt or (b) a reactant, such as benzyl chloride, which reacts with the sulfide ly-Product to form the sulfonium salt in situ. Additionally, the cathode may be a single item to be coated or a series of such items which can be removed en masse or individually. The concentration of the sulfonium salt in the electrolysis solvent is not critical. However, a sufficient.

9 surface. This drift does in some instances result in hydrogen bubbles being evolved (gassing) when water is ferred in some instances to minimize the formation of hydrogen gas.

SPECIFIC EMBODIMENTS The following examples further illustrate the invention:

Unless otherwise stated, the electroylysis solvent is water, the cathode potential is expressed in volts in comparison with a saturated calomel electrode (SCE),

and the anode is a carbon or graphite rod.

Example l I Preparation and Coating of Bibenzyl on a Platinum Cathode The technique of controlled-potential electrolysis is explained in detail in Meites, Controlled Potential Electrolysis in A. Weissberger Editor, Technique of Organic Chemistry, Vol. 1, 3rd. Edition (lnterscience, New York, 1959, pages 328l3333). This technique and a three-compartment glass electrolysis cell as described by Meites was employed for the electroreduction. A platinum cathode and graphite anode were used, and a magnetic stirring bar was used to agitate the catholyte. The cathode compartment contained 7.7 X 10 moles of benzyldimethylsulfonium tosylate (m.p. l24-125C.) and approximately 200 ml. of 0.2 N tetraethylammonium bromide (TEAB) in dimethylformamide (DMF). The central and anode compartments contained only 0.2 N TEAB in DMF solution. The reducing potential-at the platinum cathode was maintained at l .1 volts versus the SCE. The reduction was carried out at room temperature and the cathode compartrnent was continuously flushed with nitrogen. Initial current was 42 milliamperes (ma) and this dropped to about 0.2 ma. in the course of the reduction which was about 12 hours. The resulting DMF solution in the cathode compartment was analyzed for bibenzyl by vapor phase chromatography (VPC) and mass spectrometry. Measured yield of bibenzyl by VPC was percent of original sulfonium compound used.

In a similar experiment, water replaced DMF as the electrolysis solvent and bibenzyl coated the cathode. The coating was removable by washing the coated cathode with DMF or other organic solvents.

Similar results were obtained by using an aqueous solution of the tosylate and replacing the platinum cathode with a steel (ca. 1 in. surface). The reduction was carried out at -l .25 volts vs. SCE; current ranged from 20 ma. to 34 ma. over a 2 minute time interval. Bibenzyl coated the steel chip.

Example 2 g Preparation and Coating of p,p'-Dichlorobibenzyl This example utilizes the technique of uncontrolled potential electrolysis. In this technique, the applied potential (driving potential) is' set at a constant value and the cathode potential (reducing potential) is uncontrolled, i.e., it is allowed to drift to increasingly negative values as the sulfonium reactant is depleted and/or an electrically-resistant coating is formed on the cathode the electrolysis solvent. The electrolysis cell is a threecompartment glass cell in which the cathode compartment was separated from the anode compartment by a central compartment and porous glass frits. The anode was a carbon rod. The anode and central compartments were filled with a 0.5 N aqueous KCl solution.

The reaction temperature was 25C. The cathode com-- partment was filled with 200 ml. of a 0.5 N aqueous solution of p-chlorobenzyldimethylsulfonium chloride. A driving voltage of 3 to 5 volts was applied and the reduction occurred using various metals as cathodes (surface area E 1.5 in. The results are summarized in Table II.

ma. milliampercs In all examples,

In each instance, some gassing was observed and the crystalline coating was identified as p,pdichlorobibenzyl (m.p., 8995C.). Example 3 Preparation and Coating of 2,2,4,4'-Tetrachlorobibenzyl Using the uncontrolled potential technique and general procedure set forth in ExampleZ, except for the sulfonium salt and catholyte concentration, the following runs were made using a 0.3 N aqueous solution of 2,4-dichloi'obenzyldimethylsulfonium chloride and several types of cathodes. Unless otherwise noted, all cathodes had about 1 square inch of surface area; reaction times were four minutes.

' four wires (1.009" in diameter l inch long "wire 0.125" in diameter a 1 inch long In two similar experiments, except for the applied voltages, two steel cathodes were coated as follows:

Table IV Driving Initial Potential Current Initial Cathode No. (Volts) (ma.) Potential (Volts) l6 I I00 I7 30 400 6 No gassing was observed in Run 16 for 30 seconds, after which a small amount did occur. Run 17, gassing occurred immediately in large quantitiesa In four other similar runs, except that controlledpotential electrolysis technique replaced the uncontrolled electrolysis technique, various cathodes were coated as follows:

Table V Cathode Cathode Potential Current (ma.) Time No. Metal (Volts) Initial Final (min.)

l8 steel O.9 40 6.5 5 l9 platinum 0.7 20 5 5 20 copper .3 25 2 4 21 aluminum l.) 20 35 10 Some gassing was observed in Run 21 but not in 18-20.

In every instance above, 2,2,4,4'-tetrachlorobibenzyl coated the cathode surface; the product was a white crystalline solid; m.p., to C.

Example 4 Preparation and Coating of p,p-Difluorobibenzyl Using the uncontrolledpotential technique and general procedure set forth in Example 2, a 0.25 N aqueous solution of p-fluorobenzyldimethylsulfonium chloride (no KCl in catholyte) was electrolyzed under the following conditions: I

Table VI Initial Cathode Initial Cathode Potential Current Time No. Metal (Volts) (mat) (min.)

1 steel -096 l0 l5 '2 copper l.l 10 15 In both instances, the cathode was coated with p,pdifluorobibenzyl and no gassing was observed. Example 5 Preparation and Coating of p,p'-Dinitrobibenzyl An aqueous solution 0.04 N in p-nitrobenzyldimethylsulfonium chloride and 0.5 N in KC] was placed in a beaker equipped .with a carbon rod anode and a copper or platinum cathode. An electrical potential was applied such that the cathode potential was between 0.6 and -O.8 volts vs SCE. A yellow crystalline compound coated the surface of the cathode. The compound was identified as p,p-dinitrobibenzyl. Example 6 I 7 Preparation and Coating of p,p'-Bis(t-Amyl)- Bibenzyl I Using the controlled-potential electrolysis technique as in Example 1, the electrolysis cell was filled with a 0.3 N aqueous KC] solution and the catholyte was additionally made 0.1 N in p-t-amylbenzyldimethylsulfonium chloride. A carbon anode and steel cathode (l in?) was used. The solution was electrolyzed for 2 min. at 25C. under a cathode potential of l .3 volts during which time the current decayed from 40 to 2 ma. The powdery white coating was identified as a mixture containing a major proportion of p,p-bis(t-amyl)bibenzyl and a minor amount of p-t-amyltoluene. Example 7 Preparation and Coating of p,p-Bis(Dodecyl) Bibenzyl Using the uncontrolled potential technique and general procedure as set forth in Example 2, except that no supporting electrolyte was used in the catholyte, a 0.215 N aqueous solution of palkylbenzyldimethylsulfonium chloride was electrolyzed for minuets under the following conditions:

Catholyte was 0.5 N in KCl "Reaction time was 15 min.

In each instance, the cathode was coated with a mixture of p,p-bis(alkyl)bibenzyl and p-alkyltoluene, The alkyl substituent was a mixture of C to C alkyl groups with an average of C The product therefore contained a random mixture of bis(C to C substituted bibenzyl and p-(C to C )-toluene, e.g., 12 2S' 6 4 2 2 6 4 12 25a 12 2s s- H CH CH C H C H etc. The coating afforded excellent rust protection for the steel and iron cathodes no rust was. observed on the coated portion even after 2 days in Water while severe rusting was observed on the uncoated portion (portion held above the catholyte during electrolysis). Example 8 Preparation and Coating of p,p-Divinylbenzyl Using the uncontrolled potential technique and the general procedure set forth in Example 2, except for the sulfonium salt and c'atholyte concentration, a 0.3 N aqueous solution of p-vinylbenzyldimethylsulfonium nitrate was electrolyzed for 45 minutes under the following conditions:

Table Vlll Cathode Cathode Potential lnitial No. Material (Volts) Current (ma.) Gassing 1 steel 'l.1 15 no 2 stainless 1.3 20 yes steel 3 phosph ated l .4 15 yes steel 4 iron wire -l.2 15 no 5 platinum -l.0 15 very little I 6 copper --l.() 15 no 7 aluminum 1 .9 15 yes 8 aluminum* 1.5 15 yes 9 molybdenum l.4 15 yes 10 tin l.5 yes 1 l zinc l .5 no i2 silver wire -l.5. 7 15 no 13 lead l.0 15 no 14 magnesium -l.9 l0 yes 15 titanium -l .5 17 yes 16 graphite l .3 15 no Freshly polished with steel wool other aluminum cathode-merely cleaned with solvent,

More gassing was observed on magnesium than for any other metal.

In each instance the coating was identified as p,p divinylbibenzyl. The coated cathodes were subsequently removed and heated at C. for 12 hours. The coating thus obtained was a hard, clear, seemingly col orless polymer film which provided amazingly good rust protection for the steel and iron articles and good protection against oxidation for metals, such as copper, even when stored in an air oven for 48 hours at C.

In this experiment, as in substantially all of the examples presented herein, the coating was noted to give. similar protection to the edges, corners and rough surfaces as well asto the smooth flat surfaces. The uncured coating was easily removed by washing the surface with CCl Example 9 Preparation and Coating of a,a'-Dimethylbibenzyl Using the controlled-potential electrolysis technique and procedures as set forth in Example 1, ml. of 0.5 N tetraethylammonium tosylate (TEAT) in dimethylformamide (DMF) containing 0.0099 moles of a-methylbenzyldimethylammonium tosylate (mp, l 10l 13C.) was electrolyzed at a cathode potential of l.2 volts for 24 hours at 25C. during which time the current decayed from 62 to 0.2 ma. The center and anode compartments contained 0.5 N TEAT in DMF and the anode was graphite. The DMF soluble product was identified as a,a'-dimethylbibenzyl; product yield was 90 percent. Similar results are obtained by replacing DMF with water or ethanol-water mixtures except that the product coats the cathode. A lead cathode was used.

Example 10 Preparation and Coating of n-Octane Using the uncontrolled potential technique and general procedure set forth in Example 2, except for the sulfonium salt and catholyte concentration, a 0.1 N aqueous solution of n-octyldimet hylsulfonium nitrate was electrolyzed using a steel cathode. Several runs were conducted at cathode potentials between O.5 and 1.1 volts and in each instance the current quickly decayed to zero. The cathode potential also drifted in each instance to more negative values, indicating good cathode coverage by a resistant coating. At cathode potentials of l .3 to l.5 volts, the current remained essentially constant at 15 ma; slight gassing was observed. The cathode was withdrawn and the oily coating analyzed by mass spectroscopy; n-octane was identified as the major product. Similar results were obtained by using a lead cathode, Example 11 Using the uncontrolled potential technique and general procedure set forth'inExample 2, except for the sulfonium salt and catholyte concentration, a 0.2 N aqueous solution of (no KCl in catholyte) was electrolyzed in three separate runs using various cathodes (surface area of each was ca. 1.5 inf).

' Table 1X Several runs were made using various cathodes and 2 minute reaction times. The results are tabulated in Table X:

Table X Initial Cathode lnitial Cathode Current No. Material Potential (Volts) (ma.) Gassing 1 steel l.05 yes 2 lead l.2 no 3 platinum ().5 15 yes 4 copper ().7 15 yes The oily coatings thus produced were found to be a mixture of p-hydroxyphenyl n-butyl sulfide and the coupled product (HOC H.,S+CH Gil -r Similar results are obtained using other sulfonium salts, other solvents, other materials as cathodes and at voltages and amperages as described herein.

The coatings as illustrated above and those produced by using other sulfonium reactants as described herein are useful as protective or lubricating coatings, as electrical insulators, and other like uses.

Example 13 Using the controlled-potential electrolysis technique and general procedure set forth in Example 1, a 0.5 N aqueous KCl solution containing triphenylsulfonium chloride (10 g./200 ml.) was electrolyzedusing various metal cathodes. The results are summarized in Table XI.

Table X1 Cathode Cathode Initial No. Metal Potential (Volts) Current (ma.) Gassing '1 steel 1 .4 16 yes 2 platinum l.45 7.6 yes 3 copper 1.8 14 yes The products were biphenyl and phenyl sulfide. Example 14 Using the uncontrolled potential and general procedure set forth in Example 2, 0.6 N aqueous solution (no KCI) of a resistivity of less than about 10 ohm-cm. at 300 K. and being used as a cathode in a system comprising an anode, a cathode, an aqueous electrolysis solvent which is predominantly water and a means for applying and maintaining an electrical potential between said anode and cathode, said process comprising subjecting a solution of an organic monosulfonium salt in said aqueous electrolysis solvent to an electrical potential sufficient to reduce said salt; said hydrophobic coating being substantially insoluble in said electrolysis solvent.

2. The process defined in claim 1 wherein said electrolysis solvent is water.

3. The process defined in claim 1 wherein said cath- 4 ode is a conductor metal having a resistivity of less than R1 AG 5 wherein R R and R are hydrocarbon or halo-, hy-

droxyor cyano-substituted hydrocarbon groups having up to 30 carbon atoms, and A is an electrolytically acceptable anion. v

6. The process defined in claim 5 wherein R and R are each lower alkyl or hydroxyalkyl of one to four car bon atoms.

7. The process defined in claim 6 wherein R has the formula wherein n is an integer from O to 5, and R is an alkyl, aryl, aralkyl, alkaryl, cycloalkyl or alkenyl group or corresponding halo-substituted group. ,8. The process defined in claim 7 wherein n is l and R is alkyl, alkenyl, or an ester or amide group of the formula defined by claim 5.

14. The coatedproduct according to claim 9, the

coating of which is subsequently cured.

15. The process as defined in claim 1 wherein said electrical potential is maintained at a substantially constant value.

16. A process for preparing a compound of the for-' rnula R H or R R comprising subjecting an or-' garric sulfonium salt in an electrolysis solvent to an electrical potential sufficient to reduce said sulfonium salt; said salt having the formula 23. The process defined in claim 1 wherein said solution is stirred during the process.

24. The process defined in claim 3 wherein said cathode is iron, steel, copper, platinum, silver, aluminum,

Q 5 molybdenumflin, zinc, lead, magnesium or titanium, R1 S B2 A and wherein said organic monosulfonium salt is i benzyldimethylsulfonium tosylate, 4- R chlorobenzyldimethylsulfonium chloride, 2,4- dichlorobenzyldimethylsulfonium chloride, 4- 1o fluorobenzyldimethylsulfonium chloride, 4- wherein R R and R are hydrocarbon or halo-, hynitrobenzyldimethylsulfonium chloride, 4-tdroxyor cyano-substituted hydrocarbon groups havamylbenzyldimethylsulfoniurn chloride, 4- ing up to 30 carbon atoms; said process being conalkylbenzyldimethylsulfonium chloride wherein said ducted in an electrolysis system comprising an anode, alkyl substituent is from a C to C alkyl group, 4- a cathode, an electrolysis solvent and a means for ap- 15 vinylbenzyldimethylsulfonium nitrate, plying and maintaining an electrical potential between a-methylbenzyldimethylsulfonium tosylate, said anode and cathode. n-octyldimethylsulfonium nitrate,

e '7 1 e w e e w e29 G E 6-GE 3%W I E 17. The process defined in claim 9 wherein R isvinyl or ailyl.

18. The process defined in claim 17 wherein the hydrophobic coating thus obtained is subsequently cured.

19. The coated product produced by the process as defined by claim 18.

20. The process defined by claim 3 wherein said cathode is iron, copper, nickel, aluminum, tin, zinc, lead, or an alloy thereof.

21. The process defined in claim 4 wherein said cathode is iron or an alloy thereof.

22. The process defined in claim wherein R is an activated hydrocarbon or halo-, hydroxyor cyanosubstituted hydrocarbon group, and R and R are alkyl or hydroxyalkyl groups of from 1 to carbon atoms.

triphenylsulfonium chloride or UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,852,174 DATED December 3, 1974 |NVENTOR(S) 3 William J. Settineri and Ritchie A. Wessling it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 38: "not" should be most.

Column 2, line 48: o"constant should be 0' constant.

Column 11, line 65: "along" should be long.

Signed and Sealed this twenty-ninth Day of July 1975 [SEAL] A ttes I:

RUTH C. MASON C. MARSHALL DANN Alresring Officer ('ummr'ssr'mu'r ujlure'nm and Trademarks

Claims (26)

1. A PROCESS FOR APPLYING A NONPOLYMERIC HYDROPHOBIC COATING TO A SOLID ELECTROCONDUCTIVE ARTICLE HAVING A RESISTIVITY OF LESS THAN ABOUT 10**8 OHM-CM. AT 300*K. AND BEING USED AS A CATHODE IN A SYSTEM COMPRISING AN ANODE, A CATHODE, AN AQUEOUS ELECTROLYSIS SOLVENT WHICH IS PREDOMINANTLY WATER AND A MEANS FOR APPLYING AND MAINTAINING AN ELECTRICAL POTENTIAL BETWEEN SAID ANODE AND CATHODE, SAID PROCESS COMPRISING SUBJECTING A SOLUTION OF AN ORGANIC MONOSULFONIUM SALT IN SAID AQUEOUS ELECTROLYSIS SOLVENT TO AN ELECTRICAL POTENTIAL SUFFICIENT TO REDUCE SAID SALT; SAID HYDROPHOBIC COATING BEING SUBSTANTIALLY INSOLUBLE IN SAID ELECTROLYSIS SOLVENT.

2. The process defined in claim 1 wherein said electrolysis solvent is water.

3. The process defined in claim 1 wherein said cathode is a conductor metal having a resistivity of less than about 10 2 ohm-cm. at 300* K.

4. The process defined in claim 3 wherein said cathode is iron, copper, or an alloy thereof.

5. The process defined in claim 1 wherein said sulfonium salt has the formula

6. The process defined in claim 5 wherein R2 and R3 are each lower alkyl or hydroxyalkyl of one to four carbon atoms.

7. The process defined in claim 6 wherein R1 has the formula

8. The process defined in claim 7 wherein n is 1 and R4 is alkyl, alkenyl, or an ester or amide group of the formula

9. The process defined in claim 8 wherein R4 is alkyl of 4 to 18 carbon atoms or vinyl or allyl.

10. The process defined in claim 5 wherein said electrolysis solvent is water.

11. The coated product produced by the process as defined by claim 1.

12. The coated metal product produced by the process as defined by claim 3.

13. The coated product produced by the process as defined by claim 5.

14. The coated product according to claim 9, the coating of which is subsequently cured.

15. The process as defined in claim 1 wherein said electrical potential is maintained at a substantially constant value.

16. A process for preparing a compound of the formula R1-H or R1-R1 comprising subjecting an organic sulfonium salt in an electrolysis solvent to an electrical potential sufficient to reduce said sulfonium salt; said salt having the formula

17. The process defined in claim 9 wherein R4 is vinyl or allyl.

18. The process defined in claim 17 wherein the hydrophobic coating thus obtained is subsequently cured.

19. The coated product produced by the process as defined by claim 18.

20. The process defined by claim 3 wherein said cathode is iron, copper, nickel, aluminum, tin, zinc, lead, or an alloy thereof.

21. The process defined in claim 4 wherein said cathode is iron or an alloy thereof.

22. The process defined in claim 5 wherein R1 is an activated hydrocarbon or halo-, hydroxy- or cyano-substituted hydrocarbon group, and R2 and R3 are alkyl or hydroxyalkyl groups of from 1 to 10 carbon atoms.

23. The process defined in claim 1 wherein said solution is stirred during the process.

24. The process defined in claim 3 wherein said cathode is iron, steel, copper, platinum, silver, aluminum, molybdenum, tin, zinc, lead, magnesium or titanium; and wherein said organic monosulfonium salt is benzyldimethylsulfonium tosylate, 4-chlorobenzyldimethylsulfonium chloride, 2,4-dichlorobenzyldimethylsulfonium chloride, 4-fluorobenzyldimethylsulfonium chloride, 4-nitrobenzyldimethylsulfonium chloride, 4-t-amylbenzyldimethylsulfonium chloride, 4-alkylBenzyldimethylsulfonium chloride wherein said alkyl substituent is from a C8 to C18 alkyl group, 4-vinylbenzyldimethylsulfonium nitrate, Alpha -methylbenzyldimethylsulfonium tosylate, n-octyldimethylsulfonium nitrate,

25. The process defined by claim 1 with the provision that said organic monosulfonium salt is not a nitrobenzyl dialkyl or dihydroxyalkyl sulfonium salt or a nitrobenzyl alkyl hydroxyalkyl sulfonium salt.

26. The product produced by the process defined by claim 25.