WO2001023343A2

WO2001023343A2 - Method of manufacturing alkylated phenylnaphthylamine compositions; and products

Info

Publication number: WO2001023343A2
Application number: PCT/US2000/024500
Authority: WO
Inventors: John Ta-Yuan Lai
Original assignee: Noveon Ip Holdings Corp.
Priority date: 1999-09-30
Filing date: 2000-09-07
Publication date: 2001-04-05
Also published as: CZ20021049A3; WO2001023343A3; CA2382802A1; AU7119300A; EP1216224A2; BR0014367A; MXPA02003261A

Abstract

A method for manufacturing an alkylated phenylnaphthylamine composition includes alkylating nonalkylated phenylnaphthylamine with olefin in the presence of clay catalyst without subsequent removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine. Suitable nonalkylated phenylnaphthylamines include N-phenyl-1-naphthylamine, its derivatives, and mixtures thereof. The alkylated phenylnaphthylamine compositions can be used in antioxidant and lubricant compositions.

Description

METHOD OF MANUFACTURING ALKYLATED PHENYLNAPHTHYLAMINE COMPOSITIONS;

AND PRODUCTS

Field of the Invention

This invention relates to methods of manufacturing alkylated phenylnaphthylamine compositions and the compositions formed thereby. In particular, the invention relates to methods of manufacturing alkylated phenylnaphthylamine compositions by the reaction of a phenylnaphthylamine reactant with at least one ole in in the presence of a clay catalyst.

Background of the Invention

Diarylamine antioxidants have been used to improve the oxidative stability of lubricants. Depletion of these antioxidants however, occurs during the use of such lubricants at high temperatures in the presence of oxygen. A lack of antioxidants can lead to oxidative degradation and a nonfunctional lubricant.

Diarylamine antioxidant compositions have been formed by alkylation of diarylamines, such as diphenylamines and phenylnaphthylamines. Preferred phenylnaphthylamine antioxidant compositions typically contain greater that 50% monoalkylated phenylnaphthylamine. Monoalkylated phenylnaphthylamine antioxidants are useful in synthetic ester lubricant stabilizer compositions as taught in PCT patent application publication No. WO95/16765. Obtaining these compositions typically requires a balance between forming monoalkylated phenylnaphthylamines as a result of, for example, reaction conditions and reactants that strongly promote alkylation and leaving nonalkylated phenylnaphthylamines as a result of, for example, reaction conditions and reactants that do not produce adequate alkylation. In addition, the reaction conditions are typically selected so that the monoalkylated phenylnaphthylamines do not crack back (e.g., by removal of the alkyl substituent) tononalkylated phenylnaphthylamines. The preference for monoalkylated phenylnaphthylamines in antioxidant compositions is related to their ability to form oligomers with dialkylated diphenylamine. Dialkylated phenylnaphthylamines can not, or are significantly less likely, to form oligomers. Monoalkylated phenylnaphthylamines are also preferred because nonalkylated phenylnaphthylamine can form cross-linked structures that can increase sludge during the aging of the lubricant.

Summary of the Invention

Generally, the present invention relates to alkylated phenylnaphthylamine compositions, antioxidant compositions, and lubricant compositions containing alkylated phenylnaphthylamine, as well as the formation of such compositions. One embodiment is a method for manufacturing an alkylated phenylnaphthylamine composition. The method includes alkylating nonalkylated phenylnaphthylamine with olefin in the presence of clay catalyst. Suitable phenylnaphthylamines include N-phenyl-1 - naphthylamine, its derivatives, and mixtures thereof. This method can be used to form alkylated phenylnaphthylamine compositions that include no more than 5 wt.% nonalkylated phenylnaphthylamines based on the combined weight of the nonalkylated phenylnaphthylamines, monoalkylated phenylnaphthylamines, and polyalkylated phenylnaphthylamines in the alkylated phenylnaphthylamine composition. This method can be used to form alkylated phenylnaphthylamine compositions that include no more than 5 wt.% polyalkylated phenylnaphthylamines based on the combined weight of the nonalkylated phenylnaphthylamines, monoalkylated phenylnaphthylamines, and polyalkylated phenylnaphthylamines in the alkylated phenylnaphthylamine composition.

This method can be used to form alkylated phenylnaphthylamine compositions that include no more than 10 wt.% polyalkylated phenylnaphthylamines and nonalkylated phenylnaphthylamines combined, based on the combined weight of the nonalkylated phenylnaphthylamines, monoalkylated phenylnaphthylamines, and polyalkylated phenylnaphthylamines in the alkylated phenylnaphthylamine composition. Another embodiment of the invention includes a method of manufacturing a lubricant composition. This method includes lubricant and an antioxidant composition. The antioxidant composition includes an alkylated phenylnaphthylamine composition formed by monoalkylation of a phenylnaphthylamine reactant without subsequent removal of nonalkylated phenylnaphthylamines and polyalkylated phenylnaphthylamines. For example, the alkylated phenylnaphthylamine composition can be formed by alkylating nonalkylated phenylnaphthylamines with olefin in the presence of clay catalyst

Another embodiment of the invention is a phenylnaphthylamine composition that is formed by monoalkylation of a phenylnaphthylamine reactant with olefin in the presence of clay catalyst. The phenylnaphthylamine composition is formed in such a manner that there is no need to remove nonalkylated phenylnaphthylamines or polyalkylated phenylnaphthylamines in order to form a suitable antioxidant composition.

Yet another embodiment of the present invention is a lubricant composition. This composition includes a lubricant and an antioxidant composition. The antioxidant composition includes an alkylated phenylnaphthylamine composition formed by monoalkylation of a phenylnaphthylamine reactant without subsequent removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine.

Detailed Description of the Preferred Embodiment The present invention is applicable to methods of forming phenylnaphthylamine compositions and the compositions formed thereby. In particular, the present invention is directed to methods of forming alkylated phenylnaphthylamine compositions by the reaction of a phenylnaphthylamine reactant with at least one olefin in the presence of a clay catalyst. While the present invention is not limited to the following aspects of the invention, an appreciation of the invention will be gained through a discussion provided below.

Reference herein to the weight percentage (wt.%) of any nonalkylated, monoalkylated, or polyalkylated phenylnaphthylamines in a composition is, unless otherwise specified, based on the total weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the particular composition (for example, in an alkylated phenylnaphthylamine composition or a reaction composition). The terms "monoalkylated," monoalkylation," "monoalkylates,"

"monoalkylate," and the like when used to refer to a chemical reaction, unless otherwise specified, is directed to a reaction in which at least 50 wt.% of the reaction product is phenylnaphthylamine alkylated to produce a single alkyl substituent. It will be recognized that there may be alkylation of some phenylnaphthylamine resulting in two or more alkyl substituents.

Reference herein to "monoalkylated phenylnaphthylamine," unless otherwise specified, refers to phenylnaphthylamine alkylated to produce a single alkyl substituent.

Reference herein to "polyalkylated phenylnaphthylamine," unless otherwise specified, refers to phenylnaphthylamine alkylated to produce two or more alkyl substituents.

Reference herein to "nonalkylated phenylnaphthylamine," unless otherwise specified, refers to phenylnaphthylamine reactant as well as any phenylnaphthylamine that does not have an alkyl substituent.

Components of the Reaction

Phenylnaphthylamine Reactant

A phenylnaphthylamine reactant is alkylated, preferably monoalkylated, to produce an alkylated phenylnaphthylamine composition. The phenylnaphthylamine reactant includes one or more phenylnaphthylamines. Suitable phenylnaphthylamines include N-phenyl- 1 -naphthylamine and N-phenyl- 1 -naphthylamine derivatives. Suitable derivatives include N-phenyl- 1 -naphthylamine substituted with, for example, halogen, hydroxyl, amino, amido, thio and alkoxy functional groups and the like. Preferably, the N-phenyl- 1 -naphthylamine derivatives are substituted N-phenyl- 1-naphthylamines where the substitution is not at the para position of the phenyl substituent and the derivatizing functional groups do not substantially interfere with alkylation of the phenylnaphthylamines. The phenylnaphthylamine reactant itself or a solution of the phenylnaphthylamine reactant is used in the alkylation reaction. Preferably, the initial phenylnaphthylamine reactant is essentially free (defined as no more than 5 wt.%) of impurities. One commercial source of suitable N-phenyl- 1 -naphthylamine is Aldrich Chemical Corp., Milwaukee, WI.

Olefins

Olefins are used to monoalkylate the phenylnaphthylamine reactant. The olefins typically alkylate one of the aromatic rings of the phenylnaphthylamine reactant, for example, the aromatic ring that is alkylated is believed to be the phenyl substituent of the phenylnaphthylamine. Preferably, the olefins of the present invention have only a single carbon-carbon double bond and have 4 to 18 carbon atoms.

Tertiary olefins and α-olefins are particularly suited for alkylation of the phenylnaphthylamine reactant. Tertiary olefins for use in forming alkylated phenylnaphthylamine compositions include compounds with terminal or internal unsaturation which are capable of forming a tertiary carbon cation, e.g. an olefin in which at least one olefinic carbon atom has two substituents that are alkyl or substituted alkyl. Substituted alkyl groups include, for example, C₂-C₁₂ groups substituted with, for example, halogen, hydroxyl, carboxyl, amino, thio, cyano, keto, nitro and alkoxy functional groups and the like. The α-olefins for use in forming alkylated phenylnaphthylamine compositions include compounds with terminal unsaturation. Suitable olefins for monoalkylation of phenylnaphthylamines include, for example, diisobutylene, propylene trimer and linear α-olefins. Diisobutylene

Diisobutylene can be prepared from isobutylene. Commercially, diisobutylene is typically a mixture of two isomers: 2,4,4-trimethyl-l -pentene and 2,4,4-trimethyl-2- pentene. The first isomer is both an α-olefin and a tertiary olefin, and is generally more reactive than the other isomer in the monoalkylation reaction. In at least some commercial diisobutylene, the majority of the diisobutylene, typically at least 60 wt. % of the diisobutylene, is the first isomer (2,4,4-trimethyl-l -pentene). One commercial source of suitable diisobutylene is Neochem Corp., Bayonne, NJ.

Propylene Trimer

Propylene trimer is a branched olefin, produced by the polymerization of propylene. Propylene trimer contains isomeric nonenes, including α-olefins and tertiary olefins. The alkylation of a phenylnaphthylamine reactant using propylene trimer affords nonylated phenylnaphthylamine compositions and a minority of other reaction products. Nonylated phenylnaphthylamine refers to all phenylnaphthylamines alkylated with any nonene isomer. Commercial sources of suitable propylene trimer are Sonoco, Inc., Philadelphia, PA, Exxon Chemicals, Houston, TX, and Texaco Chemicals, Universal City, CA.

Linear α-olefins

Suitable linear α-olefins for use in forming alkylated phenylnaphthylamine compositions include compounds with terminal unsaturation in which one carbon atom of the double bond is bonded to two hydrogens. Typically, linear α-olefins are formed from, for example, the oligomerization of ethylene. Suitable α-olefins include, but are not limited to, compounds having 6 to 18 carbon atoms. Among these compounds are linear α-olefins such as, for example, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1- hexadecene, and 1-octadecene. The α-olefins can be substituted by various functional groups. Suitable functional groups include those that do not substantially interfere with alkylation of the phenylnaphthylamines by the α-olefinic bond between the last and next to last carbon atoms. Examples of suitable functional groups include hydrogen, alkyl, alkoxy, ester, cyano, aryl, alkenyl, substituted alkyl, and substituted aryl groups.

Clay Catalyst

Suitable clay catalysts include aluminosilicate clays. Aluminosilicate clays are typically compounds of aluminum silicate with metal oxides such as, for example, aluminum oxide and silicon dioxide, or other radicals. The structure of such clays are commonly a hexagonal close packed array of oxygen ions (e.g. O^2") with an aluminum ion (e.g. Al³⁺) occupying two-thirds of the octahedral holes in the ordered array. Thus, aluminum III cations of the clay catalysts are typically bonded in an octahedral arrangement to oxygen anions. Repetition of these AlO₆ units in two dimensions forms an octahedral layer. Likewise a tetrahedral layer is formed from SiO₄ silicate units.

Clays are classified according to the relative number of tetrahedral and octahedral layers. Montmorillonite clays, for example, have an octahedral layer sandwiched between two tetrahedral layers.

The clays useful in the alkylation reaction of nonalkylated phenylnaphthylamine include, but are not limited to, those used for bleaching oils and waxes. These are often referred to as acid activated clays. Such acid activated clays are commonly prepared by the acid activation of sub-bentonites or bentonites. Sub-bentonites or bentonites are typically characterized by rapid slaking when in an air dried state and only a slight swelling when placed in water. These clays include the clay mineral montmorillonite. Acid activation can be achieved, for example, by digestion in strong mineral acids such as, for example, sulfuric or hydrochloric acid, followed by washing, filtering and calcination under high temperature. Preferably, clay catalysts include small particles that can be filtered and provide relatively large surface area per unit weight. Suitable commercially available clay catalysts include Filtrol™ and Retrol™ available from Engelhard Corp. (Iselin, NJ) and Fulcat™ 14, Fulmont™ 700C, Fulmont™ 237, and Fulcat™ 22B available from Laporte Inc. (Gonzales, TX). These clays can be acid activated or acid leached clays. Acid leaching is achieved by passage of a solvent through the clay to carry away acid with it. Acid activated clays are typically preferred.

The clay catalyst can contain some water. Removal of the water prior to use can result in lighter colored reaction products. Therefore, it may be desirable to use a low water content clay or to remove the water by heating the clay, optionally, with a nitrogen sweep or with vacuum stripping.

Clay (e.g. acid activated bentonite clay), when used as a catalyst for alkylating nonalkylated phenylnaphthylamine, typically results in proportionally more monoalkylated phenylnaphthylamines than other alkylation catalysts such as A1C1₃, BF₃, Et₂O, and SbCl₃. Consequently, use of clay catalysts typically results in lower amounts of nonalkylated phenylnaphthylamines and polyalkylated phenylnaphthylamines.

In this reaction, the use of clay catalysts can produce, if desired, alkylated phenylnaphthylamine compositions where greater that about 90 wt.% of the total reaction product is monoalkylated phenylnaphthylamines and less than about 5 wt.% of the total reaction product is polyalkylated phenylnaphthylamine and less than about 5 wt.% of the total reaction product is nonalkylated phenylnaphthylamine. This desirable composition of products is a result of the clay catalyst preferentially catalyzing the alkylation reaction of the nonalkylated phenylnaphthylamines rather than the further alkylation of monoalkyl phenylnaphthylamines. The tetrahedral and octahedral layers of clay are believed to offer less access to the reactive sites in the catalyst for the monoalkyl phenylnaphthylamine molecule due to the presence of the additional alkyl groups (for example, tertiary octyl groups when the alkylating agent is diisobutylene) than the nonalkylated phenylnaphthylamine molecules. The monoalkylated phenylnaphthylamines are converted to dialkylated or another polyalkylated phenylnaphthylamines at a slower rate with a clay catalyst than with other catalysts allowing the concentration of monoalkylated phenylnaphthylamines to increase in the reaction product. By specifying clay catalyst, the use of A1C1₃, ZnCl₃, SnCl₄, H₃PO₄, BF₃, or other alkylation catalysts is restricted to those amounts that would be effective to alkylate 10 mole percent of the nonalkylated phenylnaphthylamines under the conditions specified.

Solvent

Although solvents have been used in alkylation reactions to solvate components of the reaction, it is preferred to alkylate the phenylnaphthylamine reactant with little solvent (e.g. less than 5 wt. % solvent based on the total weight of the phenylnaphthylamine reactant, olefin and clay) or no solvent at all. If solvent is used, suitable solvents include, for example, mineral spirits, toluene, and heptane.

Reaction Conditions

Typically, the phenylnaphthylamine reactant, olefin and clay catalyst are combined together to form a reaction composition. It is believed that the alkylation reaction of nonalkylated phenylnaphthylamines with at least one olefin in the presence of a clay catalyst is or is similar to a Friedel-Crafts alkylation reaction. The reaction is believed to involve, at least in part, alkylation of the phenyl substituent of the phenylnaphthylamine with the olefinic functional group of an olefin.

Reactant Quantities

In the present invention the initial mole ratios of reactants can be influenced by a variety of factors. For example, such factors include steric bulk of the reactants, reactivity of the reactants, the desired product, stability of the reactants, the possibility of side products and cost. For the alkylation reaction of the phenylnaphthylamine reactant with diisobutylene in the presence of clay, suitable mole ratios of the initial reactants (i.e., diisobutylene:phenylnaphthylamine reactant) are typically at least 2:1 to provide sufficient diisobutylene to alkylate a majority of the phenylnaphthylamine reactant in a reasonable time. If less that a 2: 1 mole ratio of diisobutylene :phenylnaphthylamine reactant is used, alkylation of the nonalkylated phenylnaphthylamines will occur, but at a slower rate. The initial mole ratio of diisobutylene:phenylnaphthylamine reactant is typically 3.5:1 or less to control the formation of polyalkylated N-phenyl- 1- naphthylamines. Preferred mole ratios of the initial reactants (i.e., diisobutylene:phenylnaphthylamine reactant) include those in the range of, for example,

2.5:1 to 3:1.

For the alkylation of the phenylnaphthylamine reactant with propylene trimer to produce monononylated phenylnaphthylamine compositions, suitable mole ratios of the initial reactants (propylene trimer:phenylnaphthylamine reactant) are at least 4:1 to provide sufficient nonene to alkylate a majority of the phenylnaphthylamine reactant.

The initial mole ratio of propylene trimer phenylnaphthylamine reactant is typically 6:1 or less to control the formation of polyalkylated phenylnaphthylamines. Suitable mole ratios of the initial reactants (i.e., propylene trimeπphenylnaphthylamine reactant) include those in the range of, for example, 4.5:1 to 5.5:1. For linear α-olefins, suitable initial mole ratios of the reactants

(α-olefin:phenylnaphthylamine reactant) are at least 1.5:1 to provide sufficient α-olefin to alkylate a majority of the phenylnaphthylamine reactant. The initial mole ratio of α-olefin:phenylnaphthylamine reactant is typically 3 : 1 or less to control the formation of polyalkylated phenylnaphthylamines. Suitable mole ratios of the initial reactants (i.e., α- olefin phenylnaphthylamine reactant) include those in the range of, for example, 2: 1 to

2.5:1.

The reaction mixture can be formed by combining the phenylnaphthylamine reactant, clay catalyst, and olefin at the same time. The reaction mixture may further be formed by the later addition of any one of the three reactants to the other two. The addition of the olefin or the phenylnaphthylamine reactant can be metered (e.g., added at a constant or varying rate), added as a single amount or in multiple batches, or by another addition method. The alkylated phenylnaphthylamine compositions are typically formed in batches, but the methods described herein can also be used in continuous processes.

When determining the amount of clay catalyst to add to the reaction mixture a variety of factors can be considered. Such factors include, for example, the desired reaction rate, the difficulty in removing the catalyst from the reaction product, and the desired reaction composition. The clay catalyst can be used in alkylation reactions in amounts starting from, for example, about 0.5 wt.%, based on the total weight of the phenylnaphthylamine reactant, clay catalyst and olefin, and may be up to about 7 wt.%, based on the total weight of the phenylnaphthylamine reactant, clay catalyst and olefin. Typically, the amount of clay is in the range of about 2 wt.% to about 6 wt.%, based on the total weight of the phenylnaphthylamine reactant, clay catalyst and olefin. Unreacted olefin contaminants can be removed from the reaction product by distillation and the clay catalyst can be removed by filtration or other known separation methods.

Reaction Temperatures Reaction temperatures are selected in view of factors such as, for example, the specific reactants, reaction rate, reaction time, and/or reaction composition. It will be understood that, during the reaction, the temperature of the reaction composition may increase above or decrease below the reaction temperature. Techniques such as, for example, cooling jackets, cooling baths, or decreasing the metering rate of the reactants can be used to eliminate or reduce these temperature excursions, if desired.

When the alkylation olefin is propylene trimer or diisobutylene, the reaction temperatures is typically no less than 110 °C to allow for alkylation of a majority of the phenylnaphthylamine reactant. Reaction temperatures are typically no more than 160 °C to avoid degradation of the reactants and reactant products (for example, cracking of the octyl groups when diisobutylene is utilized as the alkylating agent). Higher temperatures can be used if product or reactant degradation (for example, cracking) is not a concern. Preferable reaction temperatures are in the range of, for example, 120 °C to 150 °C. When the alkylation olefin is a linear α-olefin, the reaction temperatures is typically no less than 130 °C to allow for alkylation of a majority of the phenylnaphthylamines. Reaction temperatures are typically no more than 250 °C to avoid degradation of the reactants and the production of side products. Preferable reaction temperatures are in the range of, for example, 150 °C to 200 °C. In addition to temperature, the pressure in the reaction vessel can be monitored and, in some instances, controlled. The alkylation reaction can be carried out in an autoclave if high pressures, due to, for example, the vapor pressure of the olefin, are anticipated. The reaction can typically be run in air or in an inert (e.g. N₂ or noble gas) atmosphere. The amount of polyalkylated phenylnaphthylamine and nonalkylated phenylnaphthylamine present in the final antioxidant composition can be influenced by various conditions. For example, the reaction temperature and amount of clay catalyst present in the reaction composition can alter the ratios of product components. Reaction time can also influence the composition of the product. The total reaction time to obtain a desired product composition may depend on the reaction temperature and the amount of clay catalyst.

Reaction Time

Total reaction times are variable and depend on a variety of factors. Such factors include, for example, the reactants, temperature, pressure, the desired product composition, the amount of clay catalyst and the ratio of reactants. Total reaction times when the alkylation olefin is diisobutylene are often about 2 hours or more to allow for alkylation of a majority of the phenylnaphthylamines. Suitable reaction times are in the range of, for example, about 3 to 7 hours, but can range from 2 to 10 hours depending on the product composition desired. When propylene trimer or a linear α-olefin is used as the alkylating agent, total reaction times are often about 4 hours or more to allow for alkylation of a majority of the phenylnaphthylamine reactant. Total reaction times are typically 4 to 6 hours and can range from 2 to 10 hours depending on the product composition desired. The reaction time may be less if high reaction temperatures are used. These reaction times are typically useful for preparing reaction products with greater that 90%> monoalkylated phenylnaphthylamines. The times can be adjusted to obtain compositions with less monoalkylated phenylnaphthylamine.

Heat Stabilizing Agents

Heat stabilizing agents can be employed during workup to avoid changes in the color of the product due to decomposition. Suitable heat stabilizing agents include, for example, free radical scavengers such as hydroquinones, hindered phenols, phosphites, and sulfides.

Product Composition

Depending on reaction conditions and reactants, the final alkylated phenylnaphthylamine composition can be a liquid or solid. An alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.%, preferably no more than 3 wt.%, and more preferably no more than 2 wt.% nonalkylated phenylnaphthylamine (see, for example, Examples 1,4 and 5), based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

Depending on reaction conditions and reactants, an alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.%, preferably no more than 3 wt.%, and more preferably no more than 2 wt.% polyalkylated phenylnaphthylamine (see, for example, Examples 2 and 3), based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition. Depending on reaction conditions and reactants, an alkylated phenylnaphthylamine composition can be formed that contains no more than 10 wt.%, preferably no more than 6 wt.%, and more preferably no more than 4 wt.% of polyalkylated phenylnaphthylamine and nonalkylated phenylnaphthylamine combined (see, for example, Examples 2 and 3), based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

Using previously disclosed synthetic methods, purification techniques had to be employed to produce an alkylated phenylnaphthylamine composition with low amounts of starting phenylnaphthylamine or polyalkylated phenylnaphthylamine so as to be an effective antioxidant in lubricants. Previously disclosed methods employed to reduce the amounts of undesired components in a phenylnaphthylamine composition included adding a second alkylating agent that is more reactive that the first to scavenge the unreacted phenylnaphthylamine, utilizing long reaction times or high reaction temperatures to convert dialkylated product to monoalkylated product, and purification of the final reaction product mixture via, for example, distillation, recrystallization, or chromatography. These methods either require the use of excess reagents, extra synthetic steps, and/or final purification steps to remove unreacted starting material or undesired byproducts, such as polyalkylated phenylnaphthylamine.

In contrast, reacting the phenylnaphthylamines in the presence of a clay catalyst can be used to produce a phenylnaphthylamine composition containing high percentages of the desired monoalkylated phenylnaphthylamine product and low percentages of other undesirable products, as discussed above. The alkylated phenylnaphthylamine composition of the present invention is suitable for use as an antioxidant without the need of extra steps to remove nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine.

The alkylated phenylnaphthylamine compositions of this disclosure are useful as antioxidants to stabilize natural source and synthetic source oils and polymers from oxidative degradation during processing reactions and in their final use as lubricants or articles. They are useful for this purpose without subsequent removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine. They may be used in combination with other antioxidants and additives.

Lubricating fluids can be formed using the alkylated phenylnaphthylamine compositions as an antioxidant or in an antioxidant composition. The lubricating fluids usually contain at least 0.2 wt.% antioxidants, based on the total weight of the lubricating fluid, to provide sufficient protection from oxidation. The amount of antioxidant is often no more than about 2 wt.%, based on the total weight of the lubricating fluid. Typically, the amount of antioxidant is in the range of 0.5 wt.% to 1 wt.% of the total weight of the lubricating fluid.

The lubricating fluids are typically based on a lubricant such as motor, engine, turbine, or other lubricating oils and lubricating greases. The lubricating fluids may include other additives, such as, for example, friction modifiers, detergents, viscosity improvers, corrosion inhibitors, and other antioxidants. The use and types of these additives are known. Examples of suitable detergents include metal sulphonates and metal phenates. Examples of suitable viscosity improvers include polymers, such as polymethacrylates, polyacrylates, polybutenes, and polyvinyl pyrrolidones. Examples of suitable corrosion inhibitors include alkylated benzotriazoles. Examples of other antioxidants are hindered phenols, or alkylated diphenylamines. Examples Example 1

In a one Liter reactor, 240.9 grams of N-phenyl- 1 -naphthylamine, 369.6 grams of diisobutylene (Neochem Corp., Bayonne, NJ), and 30.5 grams of Filtrol™ F20 XLM clay (Engelhard Corp., Iselin, New Jersey) were combined and heated at 140° C for 5.5 hours. After completion of the reaction, a majority of excess diisobutylene was removed at 120° C and at least 80 mm Hg. The resulting product was then filtered to remove the clay. A heat stabilizing agent (0.05%) was added to the filtrate and the filtrate was heated to 170° C at 2 mm Hg for one hour to afford the desired product. This second heating step was employed to remove additional diisobutylene without cracking the monoalkylated phenylnaphthylamine or production of byproducts which could result from heating at high temperatures in the presence of the clay catalyst.

The alkylated phenylnaphthylamine reaction product was a red oil with 2.57% nonalkylated phenylnaphthylamine and 96.24% mono-t-octylphenylnaphthylamine as determined by liquid chromatography.

This example demonstrates that an alkylated phenylnaphthylamine composition can be formed by the alkylation of phenylnaphthylamine with olefin in the presence of clay catalyst. This example further demonstrates that an alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.% nonalkylated phenylnaphthylamine, no more than 5 wt.% polyalkylated phenylnaphthylamine, and no more than 10 wt.% nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine combined, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition. Example 2

The same conditions as those described in Example 1 were used except that 152.7 grams of N-phenyl- 1 -naphthylamine, 403.2 grams of diisobutylene (Neochem Corp., Bayonne, NJ) and 22.4 grams of Filtrol™ 20 XLM clay were added to the reactor. The reactants were mixed and heated to 125° C for 4 hours. The reaction product was worked up according to the same procedure as described in Example 1 to afford the desired product as a red oil with 1.8% nonalkylated phenylnaphthylamine, 95.1% mono-t- octylphenylnaphthylamine 1.4% monoalkylated phenylnaphthylamine isomer and 0.9% dialkylated phenylnaphthylamine as determined by liquid chromatography. This example demonstrates that an alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.% nonalkylated phenylnaphthylamine, no more than 5 wt.% polyalkylated phenylnaphthylamine, and no more than 10 wt.% nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine combined, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

Example 3

In a 100 ml reactor, 21.9 grams of N-phenyl- 1 -naphthylamine and 4.27 grams of Filtrol™ F20 XLM clay (from Engelhard Corp., Iselin, New Jersey) were mixed and heated to remove water. The reactor was flushed with nitrogen followed by addition of 63.5 grams of propylene trimer (Sonoco, Inc., Philadelphia, PA), heated to 150° C. The reaction mixture was then refluxed for 5 hours at 142 °C. The reaction mixture was allowed to cool and filtered to remove the clay. The yellow filtrate was combined with 0.05%) of a heat stabilizing agent and allowed to stand overnight. The reaction mixture was then placed under vacuum, at approximately 2 mm Hg, to remove excess propylene trimer. The alkylated phenylnaphthylamine reaction product was a light colored oil with 2.05%) nonalkylated phenylnaphthylamine, 1.0% polyalkylated phenylnaphthylamine and at least 95% monononyl phenylnaphthylamine isomers as determined by gas chromatography. This example demonstrates the alkylation of nonalkylated phenylnaphthylamine with olefin in the presence of 2 wt.% to 5 wt.% clay catalyst, based on the total weight of the nonalkylated phenylnaphthylamine, clay catalyst and olefin. This example further demonstrates that an alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.% nonalkylated phenylnaphthylamine, no more than 5 wt.% polyalkylated phenylnaphthylamine, and no more than 10 wt.% nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine combined, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

Example 4 The same conditions as those described in Example 3 were used except that 21.9 grams of phenylnaphthylamine, 3.55 grams of Filtrol™ F20 XLM clay and 49.1 grams of 1-tetradecene was added to the reactor and the temperature was maintained at 190 °C. The crude reaction mixture was worked up as described in Example 3 to afford the alkylated phenylnaphthylamine product as a yellow oil with 1.41% nonalkylated phenylnaphthylamine and 94.54% monotetradecylphenylnaphthylamine as determined by gas chromatography.

This example demonstrates an alkylated phenylnaphthylamine antioxidant composition formed by monoalkylation of a phenylnaphthylamine reactant without subsequent removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine. This example further demonstrates that an alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.% nonalkylated phenylnaphthylamine, no more than 5 wt.% polyalkylated phenylnaphthylamine, and no more than 10 wt.% nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine combined, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

Example 5

The same conditions as those described in Example 4 were used except that 10.95 grams of phenylnaphthylamine, 1.39 grams of Filtrol™ F20 XLM clay and 16.8 grams of 1 -decene were used. The crude reaction mixture was worked up, according to the procedure described in Example 3, to afford an orange oil with 2.86% nonalkylated phenylnaphthylamine and 96.27%) monodecylphenylnaphthylamine as determined by gas chromatography.

This example demonstrates the alkylation or nonalkylated phenylnaphthylamine with olefin in the presence of clay catalyst where the initial mole ratio of olefin to nonalkylated phenylnaphthylamine is in the range of 1.5: 1 to 5: 1. This example further demonstrates that an alkylated phenylnaphthylamine composition can be formed that contains no more than 5 wt.% nonalkylated phenylnaphthylamine, no more than 5 wt.% polyalkylated phenylnaphthylamine, and no more than 10 wt.% nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine combined, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

The present invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification.

Claims

WHAT IS CLAIMED IS:

1. A method of manufacturing an alkylated phenylnaphthylamine composition comprising a step of: alkylating nonalkylated phenylnaphthylamine with olefin in the presence of clay catalyst.

2. The method of claim 1 , wherein the step of alkylating comprises alkylating N-phenyl- 1 -naphthylamine with olefin in the presence of clay catalyst.

3. The method of claim 1, wherein the step of alkylating comprises alkylating nonalkylated phenylnaphthylamine to generate the alkylated phenylnaphthylamine composition having no more than 5 wt.% nonalkylated phenylnaphthylamine and no more than 5 wt.% polyalkylated phenylnaphthylamine, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

4. The method of claim 1 , wherein the step of alkylating comprises alkylating nonalkylated phenylnaphthylamine to generate an alkylated phenylnaphthylamine composition having no more than 10 wt.% polyalkylated phenylnaphthylamine and nonalkylated phenylnaphthylamine combined, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

5. The method of claim 1 , wherein the step of alkylating comprises alkylating nonalkylated phenylnaphthylamine with at least one olefin selected from the group consisting of diisobutylenes, propylene trimers, linear α-olefins, and mixtures thereof.

6. The method of claim 1. wherein the step of alkylating comprises alkylating nonalkylated phenylnaphthylamine with at least one olefin having 4 to 18 carbon atoms.

7. The method of claim 1 , wherein the step of alkylating comprises heating nonalkylated phenylnaphthylamine, olefin and clay catalyst to a reaction temperature in a range of l l0 °C to 200 ^oC.

8. The method of claim 7, wherein the step of alkylating comprises heating nonalkylated phenylnaphthylamine, olefin and clay catalyst to a reaction temperature in a range of 120 °C to 150 °C.

9. The method of claim 1 , wherein the step of alkylating comprises alkylating phenylnaphthylamine with olefin in the presence of 2 wt.% to 5 wt.% clay catalyst, based on the total weight of the nonalkylated phenylnaphthylamine, clay catalyst and olefin.

10. The method of claim 1 , wherein the step of alkylating comprises alkylating with an initial mole ratio of olefin to nonalkylated phenylnaphthylamine in the range of 1.5:1 to 5:1

11. A method of manufacturing a lubricant composition, the method comprising a step of: combining lubricant and an antioxidant composition, the antioxidant composition comprising an alkylated phenylnaphthylamine composition formed by monoalkylation of a phenylnaphthylamine reactant without subsequent removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine.

12. The method of claim 11 , further comprising forming the alkylated phenylnaphthylamine composition by monoalkylation of a phenylnaphthylamine reactant, wherein the alkylated phenylnaphthylamine composition has no more than 5 wt.% nonalkylated phenylnaphthylamine and no more than 5 wt.% polyalkylated phenylnaphthylamine, based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine.

13. The method of claim 11 , further comprising forming the alkylated phenylnaphthylamine composition by alkylating nonalkylated phenylnaphthylamine with olefin in the presence of clay catalyst.

14. An alkylated phenylnaphthylamine composition comprising alkylated phenylnaphthylamine formed by monoalkylation of a phenylnaphthylamine reactant with olefin in the presence of clay catalyst without removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine.

15. The alkylated phenylnaphthylamine composition of claim 14, wherein the alkylated phenylnaphthylamine composition comprises no more than 5 wt.% nonalkylated phenylnaphthylamine and no more than 5 wt.% polyalkylated phenylnaphthylamine based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the alkylated phenylnaphthylamine composition.

16. A lubricant composition comprising:

(a) lubricant; and

(b) an antioxidant composition comprising an alkylated phenylnaphthylamine composition formed by monoalkylation of a phenylnaphthylamine reactant without subsequent removal of nonalkylated phenylnaphthylamine and polyalkylated phenylnaphthylamine.

17. The lubricant composition of claim 16, wherein the lubricant composition comprises no more than 5 wt.% nonalkylated phenylnaphthylamine and no more than 5 wt.%) polyalkylated phenylnaphthylamine based on the combined weight of the nonalkylated phenylnaphthylamine, monoalkylated phenylnaphthylamine, and polyalkylated phenylnaphthylamine in the lubricant composition.

18. The lubricant composition of claim 16, wherein the alkylated phenylnaphthylamine composition is formed by alkylating nonalkylated phenylnaphthylamine with olefin in the presence of clay catalyst.

19. The lubricant composition of claim 16, wherein the amount of antioxidant composition is present in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the lubricant composition.

20. The lubricant composition of claim 16, wherein the amount of antioxidant composition is present in an amount of 0.5 wt.% to 1 wt.%, based on the total weight of the lubricant composition.