US2955016A

US2955016A - Modification of keratins with sulphones and related compounds

Info

Publication number: US2955016A
Application number: US616112A
Authority: US
Inventors: Joseph E Moore
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-10-15
Filing date: 1956-10-15
Publication date: 1960-10-04
Anticipated expiration: 1977-10-04

Description

States of America 'as represented bythe Secretary of Agriculture 7 No Drawing. Filed Oct. 15, 1956, Ser. No. 616,112

' s Claims. (01. 8-128) (Granted under Title 35, U.S. Code (1952), see. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the chemical modification of keratinrnaterials, particularly wool in the form of fibers, threads, yarns, fabrics, or wool waste. The invention is also applicable to other types of keratinous materials, as for example, various types of animalhair such as camel hair, mohair, horsehair, cattle hair, hog bristles, human hair; and additional keratins such as chicken feathers, turkey feathers, duck feathers, fur, animal hoofs, horn, synthetic keratin fibers, and so forth."

Moreparticularly this invention concerns the treatment of keratinous materials wherein the normal disulphide cross-linkages in the keratin molecule are replaced by different and novel cross-linkages derived from unsaturated sulphones, sulphoxides, or phosphine oxides whereby the properties of the keratinous-material are altered in an advantageous direction. The invention is concerned not only with the; processes whereby such chemical alterations are produced but also with the novel modified keratins produced by such chemical action. Further objects, features, and advantages of be evident from the following dc,-

wherein the Xs represent the polypeptide chains.

It is also known in the art that the disulphide linkages in a typical keratin fiber, such as wool, are the cause of certain disadvantageous properties exhibited by the fiber. Thus the disulphide linkages are readily attacked and disrupted by various agencies such as chemical reagents (particularly lalkalis, oxidizing agents, reducing agents), ultra-violet light, insects, enzymes, microprganisms, and so forth. When the disulphide bonds are disrupted the fiber is greatly weakened, thus when it is subjected .to tensile forces the individual polypeptide chains may be pulled apart since the disulphide bonds which normally hold the polypeptide chains together are no longer present or at least the number of them is reduced.

Patented Get. 4, less It has been shown in the prior art that the properties of keratins, particularly wool, can be enhanced by the process of alkylation. In this procedure, the wool is treated with a reducing agent to disrupt the disulphide linkages thus converting the -SS bond into two thiol (-SH) bonds, one attached to each polypeptide chain. The wool is then reacted with an alkylating agent such as 1,2-dibromoethane whereby the polypeptide chains are re-linked, this time through a bond. It has also been shown that the reduction and alkylation can be performed essentially simultaneously by applying a solution containing both a reducing agent and the alkylating agent to the wool.

In these known alkylating procedures the cross-linking reagent is invariably an organic dihalide such as ethylene dichloride, ethylene dibromide, methylene dichloride, trimethylene dibromide, and so forth. The use of these reagents brings about several disadvantages. In the first place most of these .dihalides, particularly those of practical importance are volatile and toxic liquids. In using these reagents losses occur by vaporization of the reagent and the iumes are dangerous from a standpoint of the health of the operators in the plant. Another point, is that the dihalides require the use of alkaline conditions for the formation of the desired S-alkylene-S- linkages. it is evident that these reagents couple with the thiol (-SH) groups by the elimination of a hydrohalic acid in accordance with the equation:

2X-SH+BrC H Br X-SCH;SX+2HBr Therefore to cause the reaction to go in the desired direction a base must be present to combine with the eliminated hydrohalic acid to remove it from the field of action. The use of strongly alkaline conditions although expedient is actually undesirableas it is well known that alkaline reagents cause a weakening of keratin fibers and causes them to melt and decrease in hand.

It has now been found that more advantageous results are attained when there is used as the cross-linking reagent compounds of an entirely different character than those used heretofore. The cross-linking reagents used in accordance with this invention are organic compounds which contain at least two olefinic unsaturated groups, these groups being linked to a sulphone, sulphoxide, or phosphine oxide radical. Representatives examples of the cross-linking reagents within the purview of this invention are given below by way of illustration and not limitation:

A. UNSATURATED SULPHONES These compounds may be represented by the formula:

0 RC=C C=CR i. i l) i i wherein the Rs stand for hydrogen or organic radicals of the aliphatic, cycloaliphatic or aroma-tic types. A typical example of R as an aliphatic hydrocarbon radical is methyl; other radicals in this area are ethyl, propyl, isopropyl, butyl', etc. Atypical example of R as an aromatic hydrocarbon radical is phenyl; other aromatic radicals are tolyl, xylyl, naphthyl, ethylphenyl, cumenyl, cyclohexylphenyl, etc. A typical example of R as a cycloaliphatic radical is cyclohexyl; other radicals in this category are methylcyclohexyl, phenylcyclohexyl, etc. Other radicals which may be used for R in the above formula are benzyl, phenylethyl, cyclohexylmethyl, cyclohexylethyl, phenylcyclohexy-l, benzylphenyl, and so forth.

R need not necessarily be a hydrocarbon radical but may contain substituent groups, for example, carboxyl COOH SOzH

e O ONH:

' 60M @NH-C O-R e (In the above formulas, R is hydrogen or a hydrocarbon radical.)

It is of course understood that the various Rs need not be identical radicals. Thus some of the Rs may be hydrogem the others may be difierent organic radicals. The invention thus includes sulphones which have an asymmetrical configuration as Well as those of a symmetrical configuration. s

Listed below are examples of individual compounds which come within the ambit of the invention. 'The nomenclature used is based on fundamental 'vinyl groups 'phone, bis(Z-phenylvinyl) attached to the sulphone radical and the carbon atoms are numbered as follows:

For example, thecompound 1-methyl-2-butylvinyl-1- ethy1-2,2'-diphenylvinyl sulphone has the. formula:

o4Hr-'-o=o-so r-o=0(OtH5)i V H CH3; CgHs v 7 Examples of individual unsaturated sul phones Divinyl sulphone, l-methylvinyl-vinyl sulphone, l-ethylvinyl-vinyl sulphone, l-propylvinyl-vinyl sulphone, 1-1sopropylvinyl-vinyl sulphone, l-butylvinyl-vinyl sulphone,

2-methylvinyl-viny1 sulphone, 2-ethylvinyl-vinyl sulphone, v

Z-propylvinyl-vinyl sulphone, 2-isopropylvinyl-vinyl sulphone, Z-butylvinyl-vinyl sulphone, 1,2-dimethylvinylvinyl sulphone, 1,2-diethylvinyl vinyl sulphone, 1',2-dipropylvinyl-vinyl sulphone, 1,2-diisopropylvinylavinyl sulphone, 1,2-dibutylvinylviny1 sulphone, 2,2-dimethylvinylvinyl sulphone, 2,2-diethylvinyl-vinyl sulphone; 2,2-dipropylvinyl-vinyl sulphone, 2,2-diisopropylvinyl-viny1 sulphone, 2,2-dibutylvinyl-vinyl' sulphone, 1,2,2-trimethy1- vinyl-vinyl sulphone, 1,2,2-triethy1vinyl-vinyl sulphone, 1,2,2-tripropylvinyl-vinyl sulphone, 1,2,2-triisopropylvinyl-vinyl sulphone, I,2,2tributylvinylvinyl sulphone, bis(l-methylvinyl) sulphone, bis(l-ethylvinyl) sulphone, bis(l -propylviny1) sulphone, bis(l -isopropylvinyl) sulphone, bis(l-butylvinyl) sulphone, bis(2- methylvinyl) sulphone, bis(2-ethylvinyl) sulphone, bis(Z-propylvinyl) sulphone, bis(2-isopropylvinyl) sulphone, bis(Z-butylvinyl) sulphone, bis(1,2-dimethylvinyl) sulphone, bis( 1,2-diethylvinyl) sulphone, bis( 1,2-dipropylvinyl) sulphone, bis(l,2-diisopropylvinyl) sulphone, bis( 1 ,Z-dibutylvinyl) sulphone, bis(2 ,2-dimethylvinyl) sulph ne, bis(2,2diethylvinyl) sulphone, bis(2,2-dipropylvinyl) sulphone, bis(2,2-diisopropylvinyl) sulphone, bis- (2,2-dibutylvinyl) sulphone, bis(l,2,2-trimethylviny1) sulphone, bis(1,2,2-triethylvinyl) sulphone, bis( 1,2,2-tripropylvinyl) sulphone, bis(1,2,2-triisopropylvinyl) sulphone, bis(1,2,2-tributylvinyl) sulphone, l-methyl-Z-ethylvinyl-vinyl sulphone, 1-methyl-2-propylvinyl-viny1 sulphone, 1-methyl-2-isopropylvinyl-vinyl sulphone, 1- methyl-Z-butylvinyl-vinyl sulphone, l-ethyl-Z-methylvinylvinyl sulphone, 1-propyl-2-rnethylvinylavinyl sulphone, 1- isopropyl-Z-methylvinyl-vinyl sulphone, l-butyl-2-methylvinyl-vinyl sulphone, 1-methy1-2,Z-diethylvinyl-vinyl sulphone, 1-propyl-2,Z-diethylvinyl-vinyl sulphone, l-isopropyl-LZ-diethylvinyl-vinyl sulphone, 1-butyl-2,2-diethylvinyl-vinyl sulphone, bis( l-methyl-Z-ethylVinyl) sulphone, bis(l-methyl-2-propylvinyl) sulphone, bis( l-methyl-Z-isopropylvinyl) sulphone, bis(l-methyl-Z-butylvinyl) sulphone, bis(l-ethyl-Z-methylVinyl) sulphone, bis(l-propyl- Z-methylvinyl) sulphone, bis(l isopropyl-Z-methylvinyl) sulphone, 'bis(l-butyl-Z-methylvinyl) sulphone, bis(lmethyl-2,2-diethylvinyl) sulphone," bis(l-methyl-2,2-dipropylvinyl) sulphone, bis(1-methyl-2,2-diisopropylvinyl) sulphone, bis(1-methyl-2,2-dibutylvinyl) sulphone, lmethylvinyl-2'-ethylvinyl sulphone, 2-methylvinyl-2'- ethylvinyl sulphone, 1,Z-dimethylvinyl-Z'-ethylvinyl sulphone, 2,2'- dimethylvinyl-2-ethylvinyl sulphone, 1,2,2-trimethylvinyl-2'-ethylvinyl sulphone, l-phenylvinyl-vinyl sulphone, 2-phenylviny1-vinyl sulphone, 1,2-diphenylvinylvinylsulphone, 2,2-diphenylvinyl-vinyl sulphone, 1,2,2- triphenylvinyl-vinyl sulphone, bis(l-phenylvinyl) sulsulphone, bis(l,2-diphenylvinyl) sulphone, bis(2,2-diphenylvinyl) sulphone, bis- (l,2,2-triphenylvinyl) sulphone, .2-phenylvinyl-2-ethylvinyl sulphone, 2-phenylviny1-2"-cyclohexylvinylsulphone, 2 -.phenylvinyl-2-benzylvinyl sulphone, 2-phenylvinyl-Z- ethoxyethylvinyl sulphone, 2-phenylvinyl-2'-phenoxyethylvinyl sulphone, 2-cyclohexylvinyl-vinyl sulphone, 2-cyclohexylvinyl-2'-ethylvinyl sulphone, 2-cycIoheXylvinyl-2'- benzylvinyl sulphone, Z-cyclohexylvinyl-Z'-ethoxyethylvinyl sulphone, 2-cyclohexylvinyl-2"-phenoxyethylvinyl B. UNSATURATED SULPHOXIDES These compounds may be represented by the formula ll RO=(IJSC=(IJR wherein R has the meaning as above described and exemplified.

C. UNSATURATED PHOSPHINE OXIDES These compounds may be represented by the formula 6 ret-rt R R RR R wherein R has the meaning as above described and exemplified and wherein R represents an organic radical for example methyl, ethyl, propyl isopropyl, butyl, phenyl, tolyl, benzyl, phenylethyl, cyclohexyl, methylcyclohexyl, phenoxyethyl, ethoxyethyl, hydroxyethyl, hydroxyphenyl, hydroxycyclohexyl, vinyl, methylvinyl, phenylvinyl, cyclohexylvinyl, benzylvinyl, and so forth.

The cross-linking reagents of this invention react by an addition of the thiol groups of the reduced protein molecule to the unsaturated (vinyl) groups of the crosslinking agent. These unsaturated groups are activated,

' and hence highly reactive, because of their adjacency to the sulphone, sulphoxide, or phosphine oxide group. The following equation illustrates the type of reaction involved In the above equation, X represents the polypeptide chain of the protein molecule.

It is evident from the above equation that the bridging or cross-linking of the peptide moieties occurs by addition of the constituents of the thiol (SH) groups to the activated, olefinic double bonds of the divinyl sulphone. A similar type of reaction will take place with the other cross-linking agents contemplated by this invention. It is evident that where the cross-linking agent has three olefinic groups (trivinyl phosphine oxide, for instance) the agent will take up three -SX groups.

In some instances, cross-linking may additionally occur through reaction of free aminogroups, hydroxyl groups, or amide groupsin the protein molecule with the unsaturated groups of the cross-linking agent. Such reaction is illustrated by the following equation:

In the above equation, X represents the polypeptide chain of the protein molecule. By cross-linking the peptide chains of keratin fibers with the novel agents fibers .which have marked advantages over. the natural or original fiber. Thus the modified fiber has an increased resistance to shrinkage and felting when subjected to laundering or other procedures wherein the fiber is contacted with aqueous, especially aqueous-alkaline fluids. The modified fiber is increased in resistance to biological degradation as by insects, bacteria, molds, and enzymes. The modified fiber has increased stability toward other potentially deleterious agencies as for example sunlight, ultra-violet light, reagents such as alkalis, acids, reducing agents, and oxidizing agents used in dyeing and other textile-treating procedures. It is obvious that to attain a maximum stabilizing efiect on the fiber, a considerable proportion, i.e., over 25% of the disulphide linkages present in the original or natural fiber should be replaced by the sulphone, sulphoxide, or phosphine oxide crosslinkages. Where partial modification isdesired the conditions of reaction, for example, the temperature, concentration of reagents, time of reaction, etc., may be varied as desired to attain any degree of replacement of disulphide linkages by the described cross-linkages. Thus by such variation of reaction conditions, the uptake of sulphone (or sulphoxide or phosphine oxide) by the fibers may be varied, for example, from about 1% to about 25%, with corresponding variation in the properties of the modified fibers. The properties of the modified fiber will also depend to a lesser extent on the type of compound chosen as the cross-linking agent. Whether or not any particular cross-linking agent is suitable for the desired type of modification of the original fiber can be determined by conducting a pilot reaction with the selected cross-linking agent and noting the characteristics of the modified fiber by conducting conventional tests thereon.

The treatment of the fiber or other keratinous material to replace the disulphide bonds by the novel sulphone, sulp-hoxide or phosphine oxide linkages is preferably carried out in what may be termed a two-step process. This procedure involves two separate phases as follows: First, the keratin is treated with a reducing agent in known manner to split each disulphide bond into thiol radicals or other radicals which behave in subsequent reaction similar to thiol radicals. The reduced keratin is then reacted with the cross-linking agent to establish the new bonds between the polypeptide chains.

Regarding the two-step process briefly noted above, the keratin is first reacted with a reducing agent. As this agent one may use various sulphur-containing, reductive, disulphide-splitting agents such as sodium sulphide, sodium sulphite, sodium bisulphite, other water-soluble salts of sulphurous or hydrosulphuric acid, or preferably organic compounds containing thiol groups. Examples of the latter are thioglycolic acid, sodium thioglycolate, beta-mercapto ethanol, 1,2-dithioglycerol, 'butyl mercaptan, and so forth. In general the reduction is carried out by immersing the keratin material in water containing an amount of the reducing agent in excess of that stoichiometrically calculated to reduce all the disulphide linkages in the amount of keratin material used. Where the reducing agent has limited solubility in water, a wetting and dispersing agent such as a long chain alkyl benzene sulphonate or long chain alkyl sodium sulphate may be added to keep the reducing agent in suspension and to promote better contact between the keratin and the reducing agent. Such conditions as temperature and time of reaction may be varied depending on such factors as the type of keratin being treated, the eificacy of the reducing agent chosen, the degree of splitting of disulphide bonds desired and so forth. In general the temperature may vary from about 20 C. to about C. Where the keratin material is a fiber such as wool or fur or hair, itis preferred to limit the upper range of temperature to about 60 C. thus to avoid degradation polypeptide chains or other undesirable side-reactions. Where refractory 'keratins such as cattle hoof or horn are being treated,

higher temperatures such as available in conducting the process under superatrnospheric pressure, maybe necessary to obtain the desired reduction of disulphide bonds. The reaction is discontinued when the desired proportion of disulphide bonds has been split. It is to be noted that splitting of the disulphide bonds results in a drastic weakening of thefiber so that the extent of the reduction can easily be followed by conducting tensile strength measurements from time to time on the fiber undergoing reaction. In general the time of reaction may vary from 30 minutes to 24 hours or more depending on the nature of the keratin material, the temperature of reaction, the eflicacy of the reducing agent, etc. The medium in the reduction may contain an alkaline agent such as sodium hydroxide, potassium hydroxide, sodium carbonate, borax, or the like to promote the splitting reaction. Wherealkaline material is used the pH of the medium should be below about pH 9 to avoid splitting of polypeptide chains. Generally it is preferred to use slightly acid or neutral conditions (about pH 7) to avoid any possibility of peptide degradation.

After the reduction step has been completed, the reduced keratin material is thoroughly washed to remove all excess reducing agent. Agents such as organic thiols if left in the keratin mass would react with the crosslinking agent applied in the next step. Solvents such as alcohol, acetone, benzene, etc. may be used as necessary to remove residual reducing agent.

The washed, reduced keratin is then immersed in a solution of the cross-linking agent in an amount of one-half moi of the agent for each thiol groupin the reduced kera- Usually,-an excess of the cross-linking agent is used to ensure complete reaction. Where the cross-linking agent is soluble in water, water may be used as a solvent for the cross-linking agent. In other'cases it may be necessary to use an inert solvent in which the agent is soluble,.for example, ethanol, propanol, butanol, benzene, dioxane, ether, petroleum ether, gasoline, hexane, etc. Where water is used as the medium, the cross-linking agent may be dispersed in the aqueous medium by the use of a wetting and dispersing agent such as a long chain alkylbenzene sodium sulphonate, long chain alkyl sodium sulphate, or the like. The temperature of the reaction may be varied from about to 100 C. Where the material being processed is a fiber such as wool, hair, fur, etc. it is preferred to use a temperature no higher thanabout 60 C.-whereby to avoid degradation of the polypeptide chains. The time of reaction will vary depending on thetemperature of reaction, the reactivity of the cross-linking agent selected and the degree of modification desired. In general the reaction may take anywhere from 30 minutes to 24 hours or more. In most cases with cross-linking agents wherein all or most of the Rs are hydrogen the creation of the new cross links will proceed more rapidly than where the agents have many organic substituents on the vinyl groups. The extent of the cross-linking reaction can be followed by conducting tensile strength or similar physical tests on the fiber from time to time sincethe establishment of the cross links between polypeptide chains will result keratin materials in which at lease some of the di-sulphide linkages of the keratin molecule have been disrupted and replaced by linkages of the type represented by where X represents the portion of the keratin molecule to which the disrupted disulphide linkage is. attached, It is an integer from 2 to 3, and M represents a compound originally containing two to three olefinic unsaturated groups, each of said groups being directly linked to a radical selected from the class consisting of the sulphone, sulphoxide, and phosphine oxide radicals, and wherein in the chemically modified keratin, the olefinic groups are satisfied by addition of an -SX and, a H radical per olefinic group.

The products of the invention, wherein the keratin is converted to linkages of the type represented by XS SX wherein the Xs represent portions of the wool molecule to which the disrupted disulpln'de linkages are attached and M represents a compound originally containing two olefinic unsaturated groups, each of said groups being directly attached to a sulphone radical, and wherein in the chemically modified wool, the olefinic groups are satisfied by addition of an SX and a H radical per olefinic group.

The invention is further demonstrated by the following example:

A lot of 8 /2 oz. white flannel wool cloth was thorough ly cleaned by successive extraction with ether, alcohol, and water. The extracted wool was dried and cut into squares of approximately 2 grams dry weight.

The wool samples were then reduced by soaking them for one hour at 50 C. in a 0.35 M solution of Z-mercaptoethanol in water, using 30 ml. per gram of wool. The reduced cloth samples were then washed thoroughly in running water. 7

The reduced Wool was then immersed in a solution of divinyl sulphone in 0.1 M sodium borate buffer solution using 50 ml. per gram of wool... The concentration of the sulphone was 2 millimoles in 50 ml. of the aqueous buffer. After agitating the wool in the sulphone solution for' 30 minutes at room temperature, the wool was washed in running water and dried.

The treated wool and samples of the original wool were subjected to various tests described below as a measure of the effectiveness of the chemical modification.

Alkali solubility, determined by immersing the wool in 0.1 N sodium hydroxide for one hour at 65 C. according to the method of Harris'and Smith (American Dyestuif Reporter, vol. 25, p. 542, 1936). The 'loss in weight was determined after thorough washing with water.

Solubility in ammonia after treatment with peracet-ic acid-carried out according to Alexander et a1 (Biochem. Journal, vol. 52, p. 177, 1952). Samples of the flannel weighing near 0.5 gram were" immersed in ml. of 1.6% peracetic acid for 25 hours. After washing the samples were treated for 24 hours with 100 ml. of 0.3 M ammonia. The loss in weight was determined after thorough washing with water. 0

Degree of supercontraction+determined by measuring the length of the fiber before and after being immersed in 5% sodium bisulphite at 100C. for 1 hour. The supercontraction is the percentage proportion of (a) the decrease in length after treatment with the sodium bisulphite to (b) the original length of the fiber. This property of the wool is an index of cross-linking of the protein molecule; the less the contraction after treatment with bisulphite', the greater is the degree of crosslinkinglf The results obtained are tabulated below:

Having thus described the invention, what is claimed is:

1. A method of chemically modifying a keratin which comprises reducing the keratin by reacting it with a sulphurcontaining, reductive, disulphide-splitting agent capable of converting the S-S bond of the keratin into two thiol (-SI-I) groups, at a pH of about to 7, then reacting the reduced keratin at a temperature about from 20 to 100 C. with a compound containing two to three olefinic unsaturated groups, each of said groups being directly linked to a radical selected from the class consisting of the sulphone, sulphoxide, and phosphine oxide radicals.

2. A method of chemically modifying wool which comprises reducing wool by reacting it with a sulphur-containing, reductive, disulphide-splitting agent capable of converting the --S-S bond of the wool into two thiol (-SH) groups, at a pH of about 5 to 7, then reacting 10 the reduced wool at a temperature about from 20 to C. with a sulphone of the formula:

rrre R R R R wherein the Rs represent radicals of the class consisting of hydrogen and hydrocarbon radicals.

3. The process of claim 2 wherein the sulphone is divinyl sulphone.

Alexander et al.: Wool, Its Chemistry and Physics," Reinhold Pub. Corp, N.Y., 1954, p. 254.

'Olcott et al.: Chemical Reviews, August 1947, p. 187.

Grant et al.: Jour. of Biol. Chem. pp. 485-493, pub. June 28, 1946.

Claims

1. METHOD OF CHEMICALLY MODIFYING A KERATIN WHICH COMPRISES REDUCING THE KERATIN BY REACTING IT WITH A SULPHUR-CONTAINING, REDUCTIVE, DISULPHIDE-SPLITTING AGENT CAPABLE OF CONVERTING THE -S-S- BOND OF THE KERATIN INTO TWO THIOL (-SH) GROUPS, AT A PH OF ABOUT 5 TO 7, THEN REACTING THE REDUCED KERATIN AT A TEMPERATURE ABOUT FROM 20 TO 100* C. WITH A COMPOUND CONTAINING TWO TO THREE OLEFINIC UNSATURATED GROUPS, EACH OF SAID GROUPS BEING DIRECTLY LINKED TO A RADICAL SELECTED FROM THE CLASS CONSISTING OF THE SULPHONE, SULPHOXIDE, AND PHOSPHINE OXIDE RADICALS.