MXPA97004385A - Carbon materials that are reacted with diazo - Google Patents

Abstract

The present invention relates to a process for preparing a carbon product having an organic group bonded to a carbon material, comprising the steps of: reacting at least one diazonium salt with a carbon material selected from a carbon powder. graphite, a graphite fiber, a carbon fiber, a canvas or canvas of coal, a product of glassy coal and a product of activated carbon in the absence of an externally applied electric current, sufficient to reduce diazon salt

Description

CARBON MATERIALS THAT ARE REACTED WITH DIAZONIUM SALTS FIELD OF THE INVENTION The invention relates to a process for the preparation of coal products. The process involves reacting a diazonium salt with a carbon material to give a carbon product having an organic group attached to the carbon material. The carbon material is selected from graphite powder, graphite fiber, carbon fiber, canvas or carbon cloth or glass carbon product and an activated carbon product.

BACKGROUND OF THE INVENTION Carbon materials are used in a wide variety of industries and products. These carbon materials include, for example, graphite powder, graphite fibers, carbon fibers, carbon cloth or canvas, vitreous carbon products and activated carbon products. Many of the uses of these carbon materials are discussed below. Graphite powder, in addition to being used as "mines" for pencils, has many uses in a variety of fields, including electrical, chemical, metallurgical and rocket components. The electrodes formed from graphite are used in furnaces for the production of steel and in the electrolytic production of chlorine, chlorates, magnesium and sodium. Graphite is also used to make metallurgical molds and crucibles, containers for chemical reactions. In the field of rockets, graphite is used for the development of rocket engine nozzles and missile nose cones. Carbon fibers and graphite fibers are used similarly in a variety of applications. Short or sectioned fibers are normally used as reinforcements in injection molding as well as in automotive brakes, where their good resistance to abrasion is desired. High performance carbon or graphite fibers are used in structural compounds, particularly composite elements used by the aerospace field. These fibers also have a wide use in sporting goods such as fishing rods, golf clubs and tennis rackets. Tapetillos or carbon canvases are simple textile products formed from long fibers of graphite carbon. They are useful in areas such as electrostatic dissipation in carpets or furniture that are related to computers, electromagnetic fields of protection and in the electrostatic painting of electromotive parts molded by laminate. The low thermal conductivity is also used in the field of rocket components. Vitreous carbon is used in the manufacture of electrical articles such as electrodes and mechanical items such as crucibles. Activated carbon exhibits excellent adsorption properties and, therefore, is used to improve the color of chemical agents, oils and fats manufactured to control the color, odor and taste of water, and food beverages. These base adsorbent carbons are also useful in gas separation processes, in the recovery of solvent vapors, in air conditioning systems and in gas masks. Many efforts have been made in recent decades to modify the surface chemistry of carbon materials. While it is possible to deposit physically adsorbed material on the surface of a carbon material, permanently changing its surface chemistry is quite difficult. PCT Patent Application WO 92/13983 describes a process for modifying the surfaces of carbon-containing materials by electrochemically reducing the diazo salts. The process is reported to be applicable, in particular, to carbon plates and carbon fibers for expensive materials. The materials containing carbon modified by the process are also described. The electrochemical reduction of the diazonium salts containing functionalized aryl radicals to covalently modify the carbon surfaces is described in Delmar et al., J. Am. Chem. Soc. 1992, 114 5883-5884. According to WO 92/13983, the process for modifying the surface of a carbon-containing material consists in inserting an aromatic group to the surface of this material by electrochemically reducing the diazonium salt that includes this aromatic group. The carbon-containing material is placed in contact with a diazonium salt solution in an aprotic solvent and is negatively charged in relation to an anode, which is also in contact with the diazonium salt solution. The use of a protic solvent is reported to prevent the electrochemical process from producing the intended product as a result of the reduction of the diazonium triple bond to a hydrazine. Despite the technology, there is a need to modify the surface chemistry of the carbon materials and impart desired properties to them.

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a process for preparing a carbon product having an organic group attached to a carbon material selected from a graphite powder, a graphite fiber, a carbon fiber , a cloth or canvas of coal, a product of vitreous coal and an activated carbon product. One process comprises the step of reacting at least one diazonium salt as a carbon material in the absence of an externally applied electrical current sufficient to reduce the diazonium salt. Another process comprises the step of reacting a diazonium salt with a carbon material in a protic reaction medium. The following description establishes additional advantages and features of the invention. These functions will be apparent from the description or will be learned by practice of the invention as described. The objectives and other advantages may be captured and achieved by the processes, products and compositions particularly pointed out in this continuing description and the appended claims.

DETAILED DESCRIPTION Processes to prepare a coal product. A first embodiment of the invention provides processes for preparing a carbon product having an organic group attached to a carbon material. The carbon material is selected from a graphite powder, a graphite fiber, a carbon fiber, a canvas or carbon cloth, a glassy carbon product and an activated carbon product. One process involves the reaction of at least one diazonium salt with a carbon material in the absence of an externally applied stream sufficient to reduce the diazonium salt. That is, the reactions in the diazonium salt and the carbon material proceed without an external source of electrons sufficient to reduce the diazonium salt. Mixtures of different diazonium salts can be used in the process of the invention. This process can be carried out under a variety of reaction conditions and in any type of reaction media, including systems or suspensions of both protic and aprotic solvents. Another process reacts at least one diazonium salt with a carbon material in a protic reaction medium. The mixtures of the different diazonium salts can be used in this process of the invention. This process can also be carried out under a variety of reaction conditions. Preferably, in both processes, the diazonium salt is formed in eitu. If desired, in any of the processes, the carbon product can be isolated and dried by means known in the art. In addition, the resulting carbon product can be treated to remove impurities by known techniques. The different preferred embodiments of these processes are discussed below and shown in the example. The carbon materials used in the processes of this invention are carbon materials selected from a graphite powder, a graphite fiber, a carbon fiber, a carbon cloth or canvas, a glassy carbon product and a product of carbon. activated carbon. The resulting carbon product is useful in known applications for untreated carbon materials such as those discussed above. More particularly, the processes of this invention can be used to prepare carbon products having advantageous properties not associated with untreated carbon materials. The processes of the invention can be carried out under a wide variety of conditions and, in general, are not limited by any particular condition. The reaction conditions must be such that the particular diazonium salt is sufficiently stable to allow them to react with carbon materials. In this form, the processes can be carried out under reaction conditions where the diazonium salt has a short life. The reaction between the diazonium salt and the carbon material is presented, for example, in a wide variety of pH's and temperatures. The processes can be carried out at an acid, neutral and basic pH. Preferably, the pH range is from 1 to 9. The reaction temperature is preferably between 0CC to 100 ° C. The diazonium salts, as is known in this field, can be formed, for example, by the reaction of the primary amines with aqueous solutions of nitrous acid. A general discussion of diazonium salts and methods for their preparation is found in Morrison and Boyd, Organic Chemistry, 5 ed. , pp 973-983 (Allyn and Bacon, Inc., 1978) and March, Advanced Organic Chemistry: Reactions, Mechanisms, and Structures. 4 Ed., (Wiley, 1992). According to this invention, a diazonium salt is an organic compound having one or more diazonium groups. In the process of the invention, the diazonium salt can be prepared prior to the reaction with the carbon material or, more preferably, generated in situ using techniques known in the art. The in situ generation also allows the use of unstable diazonium salts such as alkyl diazonium salts and avoids the unnecessary handling or manipulation of the sodium salt. Particularly preferred processes of this invention, both nitrous acid and diazonium salt are generated in eitu. A d azonium salt, as is known in this field, can be generated by reacting a primary amine, a nitrite and an acid. The nitrite can be any metal nitrite, preferably lithium nitrite, sodium nitrite, potassium nitrite, or zinc nitrite, or any organic nitrite, such as, for example, isoamylnitrite or ethylnitrite. The acid can be any acid, inorganic or organic, which is effective in the generation of the diazonium salt. Preferred acids include nitric acid, HN03, hydrochloric acid HCl and sulfuric acid, H2SO4. The diazonium salt can also be generated by reacting the primary amine with an aqueous solution of dioxide and nitrogen. The aqueous solution of nitrogen dioxide, NO2 / H2O, provides the nitrous acid that is needed to generate the diazonium salt. The generation of diazonium salt in the presence of Excess HCl may be less preferred than other alternatives, since HCl is known for stainless steel. The generation of the diazonium salt with NO2 / H2O has the additional advantage of being less corrosive to stainless steel or to other metals commonly used for reaction vessels. The generation using H2S04 / NaN02 or HNO3 / NaN02 is also relatively non-corrosive. In general, when a diazonium salt is generated from a primary amine, a nitrite and an acid, two equivalents of acid are required based on the amine. In an in situ process, the diazonium salt can be generated using an acid equivalent. When the primary amine contains a strong acid group, adding a separate acid may not be necessary in the process of the invention. The acid group or groups of the primary amine may provide one of the equivalents of acid that is needed or both. When the primary amine contains a strong acid group, preferably zero to one equivalents of additional acid are added to a process of the invention in order to generate the diazonium salt in itself. An example of this primary amine is para-aminobenzenesulfonic acid (sulfanilic acid). In general, the diazonium salts are thermally unstable. Typically it is prepared in solution at low temperatures, for example 0 to 5 ° C, and used without salt isolation. The heating solutions of some diazonium salts can release nitrogens and form either the corresponding alcohols in acid medium or the free organic radicals in basic medium.

However, to achieve the process of the invention, the diazonium salt needs only to be stable enough to allow reaction with the carbon material. In this form, the processes of the present invention can be carried out with some diazonium salts which are otherwise considered as unstable and subject to decomposition. Some decomposition processes can compete with the reaction between the carbon material and the diazonium salt and can reduce the total number of organic groups bound to the carbon material. In addition, the reaction can be carried out at elevated temperatures, where many of the diazonium salts may be susceptible to decomposition. The elevated temperatures can also advantageously increase the solubility of the diazonium salt in the reaction medium and improve its handling during the process. However, elevated temperatures can result in some loss of the diazonium salt due to other decomposition processes. The processes of the invention can be achieved by adding the reactants to form the diazonium salt in situ in a mixture or suspension of the carbon material in the reaction medium, for example, water. In this way, a mixture or suspension to be used in the process of the invention can already contain one or more reagents for I 1 / p generate the diazonium salt and the process of the invention achieved by the addition of remaining reagents. The reactions to form a diazonium salt are compatible as a wide variety of functional groups commonly found in organic compounds. In this way, only the availability of the diazonium salt for the reaction with a carbon material limits the processes of the invention. The processes of this invention can be carried out in any reaction medium that allows the reaction between the diazonium salt and the carbon material to be carried out. Preferably, the reaction medium is a solvent-based system. The solvent can be a protic solvent, an aprotic solvent or a mixture of solvents. The protic solvents are solvents, such as water or methanol, which contain a hydrogen bound to an oxygen or nitrogen and thus are sufficiently acidic to form hydrogen bonds. The aprotic solvents are solvents that do not contain acid hydrogen. Aprotic solvents include, for example, solvents such as hexanes, tetrahydrofuran (THF), acetonitrile and benzonitrile. For a discussion of aprotic and protic solvents refer to Morrison and Boyd, Organic Chemistry. 5 Ed., Pp. 228-231, (Allyn and Bacon, Inc. 1987). The processes of this invention are preferably carried out in a protic reaction medium, that is, in a protic solvent alone or in a mixture of solvents containing at least one protic solvent. The preferred protic medium includes, without limitation, water, aqueous medium containing water and other solvents, alcohols and any medium containing an alcohol or mixtures of these media. In general, the processes of this invention produce inorganic byproducts, such as salts. In some end uses, such as those discussed below, these byproducts may be undesirable and problematic. Several of the possible ways to produce a carbon product according to a process of the invention, without the unwanted inorganic salts or byproducts, are the following: First, the diazonium salt can be purified before use, removing the non-organic by-products desired by means known in the art. Second, the diazonium salt can be generated with the use of an organic nitrite as the diazotizing agent by giving the corresponding alcohol in place of an inorganic salt. Third, when the diazonium salt is generated from an amine having an acidic group and aqueous N02, no inorganic salts are formed. Fourth; The inorganic by-products can be removed by washing with a suitable solvent. neither . > > •; / 'tm.

Other forms can be known by those with expertise in this field. In addition to the inorganic by-products, a process of the invention can also produce organic by-products. These can be removed, for example, by extraction with organic solvents. Other forms may be known to those with expertise in this field.

Carbon products. The reaction between the diazonium salt and a carbon material according to a process of this invention forms a carbon product having an organic group attached to the carbon material, selected from a graphite powder, a graphite fiber, a carbon fiber, a carbon cloth or canvas, a glassy carbon product and an activated carbon product. The diazonium salt may contain the organic group that is to be bonded to the carbon black. The organic group can be an aliphatic group, a cyclic organic group, an organic compound having an aliphatic portion and a cyclic portion. As discussed above, the diazonium salt employed in the processes of the invention can be derived from a primary amine having one of these groups and capable of forming, albeit transiently, a diazonium salt. The organic group can be substituted or unsubstituted, branched or unbranched. Aliphatic groups include, for example, groups derived from alkanes, alkenes, alcohols, ethers, aldehydes, ketones, carboxylic acids and carbohydrates. Cyclic organic groups include, without limitation, allyl cyclic hydrocarbon groups. (e.g., cycloalkyls, cycloalkenyls), heterocyclic hydrocarbon groups (e.g., pyrrolidinyl, pyrrolinyl, piperidinyl, orpholinyl, and the like), aryl groups (e.g., phenyl, naphthyl, anthracenyl, and the like), and heteroaryl groups ( imidazolyl, pyrazolyl, pyridinyl, thienyl, thiazolyl, furyl, indolyl and the like). As the steric hindrance of a substituted organic group increases, the number of organic groups bonded to the carbon material from the reaction between the diazonium salt and the carbon material can be decreased. When the organic group is substituted, it may contain any functional group compatible with the formation of a diazonium salt. Examples include, without limitation, OR, COR, COOR, OCOR, COONa, COOK, C00 ~ NR4 +, halogen, CN, NR2, Sn, S03H, S03Na, S03K, S03 ~ NR4 +, NR (COR), C0NR2, N02, P03H2, P03HNa, P03Na2, N = NR, NR3 + X ~, and PR3 + X_. R is independently hydrogen, alkyl -020 (branched and unbranched) or aryl. The integer n ranges from 1 to 8 and preferably from 2 to 4. The anion X is a halide or anion derived from a mineral or organic acid.

An example of an organic group is an aromatic group of the formula AyAr-, which corresponds to the primary amine of the formula AyArNH2. In this formula, the variables have the following meanings: Ar is an aromatic radical selected from the group consisting of phenyl, naphthyl, anthracenyl, phenanthrenyl, biphenyl, and pyridinyl; A is a substituent in the aromatic radical that is independently selected from a preferred functional group described above or A is a linear, branched or cyclic hydrocarbon radical (preferably containing up to 20 carbons), unsubstituted or substituted with one or more of those functional groups; and is an integer from 1 to 5 when Ar is phenyl, from L to 7 when Ar is naphthyl, from 1 to 9 when Ar is anthracenyl, phenanthrenyl or biphenyl or from 1 to 4 when Ar is pyridinyl. Another set of organic groups that can be attached to the carbon material are organic groups substituted with an ionic group or an ionizable group as a functional group. An ionizable group is one that is capable of forming an ionic group in the medium of use. The ionic group can be an anionic group or a cationic group and the ionizable group can form an anion or a cation. Ionizable functional groups that form anions include, for example, acidic groups or salts of . / '7 ?? acidic groups. The organic groups, therefore, include organic acid derivative groups. Preferably, when it contains an ionizable group forming an anion, for example a group having a) an aromatic group and b) at least one acidic group having a pKa of less than 11, with at least one salt of a group acidic having a pKa of less than 11 or a mixture of at least one acidic group having a pKa of less than 11 and at least one salt of the acidic group having a pKa of less than 11. The acidic group pKa it refers to pKa of the organic group as a whole, and not only to the acid substituent. More preferably, the pKa is less than 10 and much more preferably less than 9. Preferably, the aromatic group of the organic group is directly bonded to the carbon black. The aromatic group may also be substituted or unsubstituted, for example with alkyl groups. More preferably, the organic group is a phenyl or naphthyl group and the acid group is a sulfonic acid group, a sulfinic acid group, a phosphonic acid group or a carboxylic acid group. The examples of these acid groups and their salts are discussed above. More preferably, the organic group is a substituted or unsubstituted sulfophenyl group or a salt thereof; a substituted or unsubstituted (polysulfo) phenyl group or a salt thereof; a substituted or unsubstituted sulfonaphthyl group or a salt thereof; or a substituted or unsubstituted naphthyl or polysulfo group or a salt thereof. A preferred substituted sulfonyl group is the hydroxysulfophenyl group or a salt thereof. Specific organic groups having an ionizable functional group forming an anion (and their corresponding primary amines which are used in the process according to the invention) are p-sulphophenyl (p-sulphanilic acid), 4-hydroxy-3-sulfophenyl (2-hydroxy-5-amino-benzenesulfonic acid), and 2-sulfoethyl (2-aminoethanesulfonic acid). The amines represent examples of ionizable functional groups that form cationic groups. For example, the amines can be protonated to form ammonium groups in acidic medium. Preferably, an organic group having an amine substituent has a pKa of less than 5. The quaternary ammonium groups (-NR3 +) and the quaternary phosphonium groups (-PR3) also represent examples of cationic groups. Preferably, the organic group contains an aromatic group, such as for example a phenyl group or a naphthyl group and a quaternary ammonium or a quaternary phosphonium group. The aromatic group is preferably directly attached to the carbon medium. Quaternized cyclic amines and even quaternized aromatic amines can also be used i L_? In this manner, the N-substituted pyridinium compounds, such as N-methyl-pyridyl, can be used in this aspect, an advantage of carbon materials having a substituted attached organic group. with an ionic or ionizable group, is that the carbon product may have an increased water dispersibility in relation to the corresponding untreated carbon material, and, in addition, its water dispersibility, the carbon products having an organic group substituted with an ionic or ionizable group can also be dispersible in polar organic solvents such as dimethylsulfoxide (DMSO) and formamide.The dispersibility in water of a carbon product increases as the number of organic groups having an ionizable group bound to the carbon material increases , or a larger number of ionizable groups are linked to a given organic group, otherwise, by increasing the number of ionizable groups associated With the charcoal product you must increase its dispersibility in water. It can be seen that the water dispersibility of a carbon product containing an amine as the organic group bonded to the carbon material can be increased by acidifying the aqueous medium. As the water dispersibility of the carbon product depends to a certain degree on the? _o '! / I'. stabilization of the charge, it is preferred that the ionic strength of the aqueous medium is less than 0.1 molar. More preferably, the ionic strength is less than 0.01 molar. When this water dispersible coal product is prepared by a process of the invention, it is preferred that ionic or ionizable groups be ionized in the reaction medium. Alternatively, the carbon product can be dried by techniques used for conventional carbon materials. However, overdrying may cause the loss of the degree of dispersibility in water. The aromatic sulfides encompass another group of preferred organic groups. Carbon products having aromatic sulfide groups are particularly useful in rubber compositions or in other compositions having reactive olefinic groups. These aromatic sulfides can be represented by the formulas -Ar-Sn-Ar'- or -Ar-Sn-Ar "where Ar and Ar 'are independently arylene groups, Ar" is an aryl and n is 1 to 8. Preferred arylene groups they include phenylene groups, particularly p-phenyl groups. Preferred aryl groups include phenyl and naphthyl. The number of sulfurs present, defined by n, preferably ranges from 2 to 4. Particular preference is given to the aromatic sulfide groups which are bis-para- (C6H) -X2- (C6H4) - and para- (CgH4) - S2- (CßHs). The diazonium salts of those aromatic sulfide groups can conveniently be prepared from their corresponding primary amines, H2N-Ar-Sn-Ar '-NH2 or H2N-Ar-Sx-Ar ".

Uses of coal products The coal products of this invention can be applied in the same applications as the corresponding untreated carbon materials. The organic groups bonded to the carbon material can be used, however, to modify and improve the properties of a given carbon material for a particular use. The organic groups can also be selected to bind to a substrate where a given carbon material is used. This bonding can take the form of reaction with the substrate through a process, such as vulcanization, neutralization, complexation or polymerization. An example is a carbon material that has NH2 groups that are used in epoxy resin based materials. The following examples are intended to illustrate the invention and not to limit it. The methods described in "Absorption, Surface Area and Porosity"; S.J. Gregg, K.S.W. Sing (Academic Press 1982) were used to measure surface areas and pore volumes.

The surface area, the non-porous surface area and the pore volume of the activated carbon were determined as described on pages 90-97. The surface area of the carbon cloth or canvas was determined using step-like isotherms. As described on pages 84-86. The surface area of the graphite fibers was determined by BET techniques using ripton.

EXAMPLE 1 Preparation of Graphite Powder Product This example illustrates the preparation of a graphite powder product using a process of the present invention. A 2.0 g sample of a graphite powder having a surface area of 11.5 m 2 / g was stirred in 14 g of water. A solution of 0.11 g of 4-chlorobenzenediazonium hexafluorophosphate in 7 g of water was added and bubbles were added. After stirring for 20 minutes, the product was collected by filtration, subjected to Soxhlet extraction with tetrahydrofuran (THF) overnight, and dried in an oven. An analysis of the product showed that it contained 597 ppm of chlorine, compared to 23 ppm of chlorine for the untreated powder. Therefore, the product contained 0.85 chlorophenyl groups per square nanometer of surface area. The ESCA analysis showed that the product contained 1.4 atomic percent chlorine. No chlorine was detected on the surface of the unreacted powder by ESCA.

EXAMPLE 2 Preparation of Graphite Powder Product This example illustrates the preparation of a graphite powder product using a process of the present invention. A solution of 0.095 g of 4-nitrobenzenediazonium tetrafluoroborate in 10 g of water was added to a stirred suspension of 2.0 g of the graphite powder of Example 1 in 18 g of water. After stirring for 15 minutes, the product was dried in an oven at 125 ° C, subjected to Soxhlet extraction overnight (THF) and dried. The ESCA analysis showed an Nls signal at 406.1 eV and one at 400.5 eV with relative areas of 5.9: 1. The 406.1 eV signal was triggered by N02 products and the 400.5 eV signal was probably triggered by the azo groups. No signal was found at 403 eV that corresponded to the diazonium groups. The combined nitrogen content was 4.0 atomic percent. No nitrogen was detected in the powder unreacted by ESCA. This establishes that the nitrophenyl groups are bound to the graphite powder product.

EXAMPLE 3 Preparation of a graphite powder product This example illustrates the preparation of a graphite powder product using the process of the present invention. A solution of p-NH3C6H N2Cl was prepared by adding a cold solution of 0.028 g of NaN02 in 3 g of water to a solution of 0.16 ml of concentrated HCl, 0.043 g p-f nilendiamine and 5 g of water, which was stirred in an ice bath. The cold diazonium solution was added to a 2.0 g suspension of graphite powder.

Example 1 and 18 g of water that was stirred at room temperature. After stirring for one hour, the product was dried in an oven at 125 ° C, subjected to Soxhlet extraction overnight with THF, and dried.A ESCA analysis of the product gave a nitrogen concentration of 4.6 atomic percent No nitrogen was detected in the unreacted powder by ESCA analysis This establishes that the aminophenyl groups are attached to the graphite powder product.

EXAMPLE 4 Preparation of a graphite fiber product This example illustrates the preparation of a graphite fiber product using a process of the present invention. Graphite fibers have an area : > l / '' '' of 0.43 2 / g and a diameter of 8 microns, and dried under nitrogen at 165 ° C for two hours. The fibers were placed in a 0.1M solution of nitrobenzenediazonium tetrafluoroborate in anhydrous benzonitrile for two minutes. The fibers were removed, rinsed twice with anhydrous benzonitrile, subjected to Soxhlet extraction overnight (THF) and dried in an oven. The ESCA analysis showed a Nls signal at 406.1 eV and one at 400.5 eV with relative areas of 4.1: 1. The signal of 406.5 eV was caused by NO2 products and that of 400.5 eV was caused by nitrogen in the original sample and by the azo groups. No signal was found at 403 eV that corresponded to the diazonium groups. The combined nitrogen content was 2.4 atomic percent. The ESCA analysis of a sample prepared by the same method with 0.01M nitrobenzenediazonium tetrafluoroborate solution gave a nitrogen percentage of 0.9. The ESCA analysis of unreacted fibers gave 0.2 atomic percent nitrogen. This establishes that the two fiber products were linked to the nitrophenyl groups.

EXAMPLE 5 Preparation of a carbon fiber product This example illustrates the preparation of a 1 Unite / * 1"1! Graphite fiber product using a process of the present invention A solution of 0.095 g of tetrafluroborate 4-nitrobenzenediazonium in 10 g of water was added to a suspension with stirring, formed of 2.0 g of Graphite fiber of Example 4 in 100 g of water After stirring for 15 minutes, the fibers were removed from the solution, dried in an oven at 125 ° C, subjected to Soxhlet extraction overnight with THF and The ESCA analysis showed an Nls signal at 406.7 eV and another at 400.5 eV with relative areas of approximately 1: 1. The signal of 406.7 eV was caused by the N02 groups and the 400.5 eV signal was caused by the nitrogen in the sample and no a signal at 403 eV corresponding to the diazonium groups was found.The content in the combined nitrogen was 1.0 atomic percent compared to 0.2 atomic percent for the unreacted fiber. neither trophoyl are attached to the graphite fiber product.

EXAMPLE 6 Preparation of a graphite fiber product This example illustrates the preparation of a graphite powder product using the process of the present invention. A solution of p-NH3C6H4N2Cl2 was prepared by adding a cold solution of 0.028 g of i?: > .? / • i, NaN02 in 3 g of water to a solution of 0.16 ml of concentrated HCl, 0.043 g of p-phenylenediamine and 5 g of water, which was stirred in an ice bath. The cold diazonium solution was added to a suspension of 2.0 g of graphite fibers from Example 4 and 100 g of water which was stirred at room temperature. After stirring for 20 minutes, the fibers were removed from the solution, dried in an oven at 125 ° C, subjected to Soxhlet extraction overnight with THF, and dried. An ESCA analysis of the product gave a nitrogen concentration of 1.7 atomic percent, compared to 0.2 atomic percent nitrogen for the unreacted fibers. This establishes that the inophenyl groups bind to the graphite fiber product.

EXAMPLE 7 Preparation of a Graphite Fiber Product This example illustrates the preparation of a graphite fiber product using a process of the present invention. A solution of 4-chlorobenzenediazonium was prepared by adding a solution of 0.014 g of NaN 2 in 3 g of water to a stirred solution of 0.025 g 4-chloroaniline, 0.070 g of 90% nitric acid and 3 g of water. After stirring for 10 minutes, the diazonium solution was added to a stirred mixture of 1 g of graphite fibers of Example 4 and 50 g of water. After stirring pL.t).) / R '? Nx for 30 minutes, the fibers were removed from the solution, dried in an oven at 110 ° C, subjected to Soxhlet extraction overnight with THF and they dried. An ESCA analysis of the product gave a chlorine concentration of 0.4 atomic percent. No chlorine could be detected in the unreacted fibers by ESCA analysis. This establishes that the chlorophenyl groups are bound to the graphite fiber product.

EXAMPLE 8 Preparation of a graphite fiber product This example illustrates a preparation of a graphite fiber product using a process of the present invention. Approximately 0.2 g of the graphite fibers of Example 4 are added to a stirred solution of 0.025 g of 4-chloroaniline, 0.070 g of 90% nitric acid and 70 g of water. A solution of 0.014 g of NaN 2 in 2 g of water was added and the mixture was stirred for 30 minutes. 4-chlorobenzenediazonium nitrate was formed in situ, which was reacted with graphite fibers. The fibers were removed from the solution, dried in an oven at 110 ° C, subjected to Soxhlet extraction overnight with THF and dried. An ESCA analysis of the product gave a chlorine concentration of 0.4 atomic percent. Chlorine could not be detected in the unreacted fibers by the "ESA analysis." This states that the chlorophenyl groups bind to the graphite fiber product.

EXAMPLE 9 Preparation of a carbon cloth or canvas product This example illustrates the preparation of a carbon cloth or canvas product using a process of the present invention. A carbon cloth or canvas having a surface area of 5.3 2 / g was reacted with chlorobenzenediazoonium hexaflorophosphate by the method of Example 1. A sample of material that would be subjected to Soxhlet extraction with THF overnight and had dried , it contained 0.4 percent atomic by ESCA analysis, compared to 0.03 percent atomic chlorine in the unreacted cloth. This establishes that the chlorophenyl groups are bound to the canvas product or carbon cloth.

EXAMPLE 10 Preparation of a glassy carbon product This example illustrates the preparation of a glassy carbon product using a process of the present invention. A small piece of a charcoal, vitreous plate (approximately 0.5 g) was stirred in a solution of 0.047 g of tetrafluoroborate of p1.2o) / "> 1rn: -: 4-nitrobenzenediazonium in 30 g of water for 30 minutes The plate was removed, dried, subjected to Soxhlet extraction with THF overnight and dried.A ESCA analysis of the product gave a concentration of 2.4 atomic percent, compared to 0.6 atomic percent of nitrogen for the plate. of unreacted vitreous carbon This establishes that the nitrophenyl groups bind to the glassy carbon product.

EXAMPLE 11 Preparation of an activated carbon product This example illustrates the preparation of an activated carbon product using a process of the present invention. An activated carbon having a nitrogen BET surface area of 762 m 2 / g, a non-porous surface area 2 of 266 m / g and a pore volume of 0.20 ml / g was reacted with a chlorobenzenediazoonium hexaflorophosphate with the method of Example 1. A sample of this material that had been subjected to Soxhlet extraction with THF overnight and had dried, contained 0.43% chlorine, compared to 0.02% unreacted carbon. Therefore, the activated carbon product contained 0.12 mmol / g chlorophenyl groups, or 0.09 chlorophenyl groups per square meter. This establishes that the chlorophenyl groups bind to the activated carbon product.

EXAMPLE 12 Preparation of an activated carbon product This example illustrates the preparation of an activated carbon product using a process of the present invention. A solution of 1.66 g of 4-nitrobenzenediazonium tetrafluoroborate in 100 g of water was added to a stirred suspension of 7 g of activated carbon of Example 11 and 70 g of water. Bubbles were released. After stirring for 15 minutes, the mixture was dried in an oven at 125 ° C. The product was Soxhlet extracted with THF overnight and dried. The ESCA analysis showed a Nls signal at 406.1 eV and another at 400.9 eV with relative areas of 3.2: 1. The signal of 406.1 eV was caused by groups N02 and that of 400.9 eV was caused by nitrogen in the original sample and by azo groups. No signal was found at 403 eV corresponding to the diazonium groups. The combined nitrogen content was 5.6 atomic percent, compared to 0.3 atomic percent nitrogen for unreacted activated carbon. This establishes that the nitrophenyl groups bind to the activated carbon product.

EXAMPLE 13 Preparation of an activated carbon product This example illustrates the preparation of an activated carbon product using the process of the present invention. A solution of p-NH C6H4N2Cl2 was prepared by adding a cold solution of 0.483 g of aNÜ2 in 10 g of water to a solution of 2.87 ml of concentrated HCl, 0.758 g of p-phenylenediamine and 30 g of water, which was stirred in an ice bath. The cold diazonium solution was added to a suspension of 7.0 g of graphite fibers from Example 11 and 63 g of water which was stirred at room temperature. After stirring for 15 minutes, the product was dried at 125 ° C for one hour, subjected to Soxhlet extraction overnight with THF, and dried. An ESCA analysis of the product gave a nitrogen concentration of 3.5 atomic percent, compared with 0.3 atomic percent nitrogen for unreacted activated carbon. This establishes that aminophenyl groups bind to the activated carbon product.

Claims (19)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following REVIVALS is claimed as property: 1. A process for preparing a coal product having an organic group attached to a carbon material, comprising the steps of: reacting at least one diazonium salt with a carbon material selected from a graphite powder, a graphite fiber, a carbon fiber, a carbon cloth or canvas, a product of vitreous carbon and an activated carbon product in the absence of an externally applied electric current sufficient to reduce the diazonium salt.
2. 2. A process according to claim 1, wherein the step of reacting is carried out with an aprotic medium.
3. 3. A process according to claim 1, wherein the step of reacting is carried out with a protic medium.
4. 4. A process according to claim 1, wherein the diazonium salt is generated in situ.
5. 5. A process for preparing a carbon product having an organic group bonded to a carbon material, comprising the step of: reacting at least one diazonium salt with a carbon material selected from a graphite powder, a graphite fiber, a carbon fiber, a carbon cloth or canvas, a glassy carbon product and an activated carbon product in a protic reaction medium.
6. 6. A process according to claim 5, wherein the diazonium salt is generated in situ from a primary amine.
7. 7. A process according to claim 6, wherein the diazonium salt is generated in situ by reacting the primary amine, a nitrite and an acid.
8. 8. A process according to claim 7, wherein the nitrite is a metal nitrite and an acid equivalent is used.
9. 9. A process according to claim 6, wherein the diazonium salt is generated in situ by reacting the primary amine, a nitrite, and the primary amine contains a strong acid group.
10. 10. A process according to claim 6, wherein the diazonium salt is generated in situ by reacting the primary amine with an aqueous solution of nitrogen dioxide.
11. 11. A process according to claim 6, wherein the protic medium is an aqueous medium, and the primary amine is an amine of the formula AyArNH2, wherein: Ar is an aromatic radical selected from the group consisting of phenyl, naphthyl, anthracenyl , phenanthrenyl, biphenyl and pyridinyl; A is independently a substituent of the aromatic radical selected from: a functional group selected from the group consisting of OR, COR, COOR, OCOR, COONa, COOK, COO ~ NR4 +, halogen, CN, NR2, Sn, S03H, S03Na, S03K, S03 ~ NR4 +, NR (COR), CONR2, N02, P03H2, P03NHa, P03Na2, N = NR, NR3 + X ~, and a linear, cyclic or branched hydrocarbon radical, unsubstituted or substituted with one or more of those functional groups; R is independently hydrogen, 1-C20 alkyl or aryl; n is an integer from 1 to 8; X is a halide or an anion derived from a mineral or organic acid; and y is an integer from 1 to 5, where Ar is phenyl, 1 to 7 when Ar is naphthyl, 1 to 9 when Ar is anthracenyl, phenanthrenyl or biphenyl or 1 to 4 when Ar is pyridinyl.
12. 12. A process according to claim 5, wherein the diazonium salt is generated in itself.
13. 13. A process according to claim 5, wherein the diazonium salt is generated from a primary amine separately from the reaction step.
14. 14. A process according to claim 5, wherein the protic reaction medium is an aqueous medium. A process according to claim 5, wherein the organic group of the diazonium salt is substituted or unsubstituted and is selected from the group consisting of an aliphatic group, a cyclic organic group or an organic compound having an aliphatic portion and a cyclical portion. 16. A process according to claim 5, wherein the protic reaction medium is water. 17. A process according to claim 5, wherein the protic medium is an alcohol-based medium. 18. A coal product prepared according to the process of claim 1. 19. A coal product prepared according to the process of claim 5. •• L _ > ) ¡&>;,!