Alkylated naphthalenes as synthetic lubricant base stocks

Abstract

This invention relates to alkylated methylnaphthalenes and their utility in lubricant base stocks. In particular, the alkylated methylnaphthalenes of the present invention have unexpectedly superior thermal and oxidative properties and may be used to improve the performance characteristics of other lubricant base oils.

What is claimed is:  
     
         1 . A method for improving the oxidative stability of a lubricant having an RBOT of ≦ about 200 minutes comprising adding to said lubricant a base oil comprising a compound of formula (I):  
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  are H, methyl, ethyl, propyl, or butyl;  
         R 3  and R 4  are an alkyl group having from about 6 to about 24 carbon atoms;  
         x is from 0 to about 2; and  
         y is from 0 to about 4;  
         with the proviso that at least one of R 1  and R 2  is other than H, and at least one of x and y is other than 0;  
         and wherein the base oil has a RBOT value of greater than about 200 minutes.  
       
     
     
         2 . The method of  claim 1 , wherein said base oil comprises at least 20 wt % of a compound of formula (I) or mixtures thereof.  
     
     
         3 . The method of  claim 1 , wherein said base oil comprises at least 50 wt % of a compound of formula (I) or mixtures thereof.  
     
     
         4 . The method of  claim 1 , wherein said lubricant comprises at least 2 wt % of said base oil.  
     
     
         5 . The method of  claim 1 , wherein R 1  is H and R 2  is methyl.  
     
     
         6 . The method of  claim 1 , wherein R 2  is H and R 1  is methyl.  
     
     
         7 . The method of  claim 1 , wherein the sum of x and y is one, R 1  is H and R 2  is methyl.  
     
     
         8 . The method of  claim 1 , wherein the sum of x and y is one, R 1  is methyl and R 2  is H.  
     
     
         9 . The method  claim 1 , wherein the sum of x and y is one.  
     
     
         10 . The method of  claim 1 , wherein the sum of x and y is greater than 1.  
     
     
         11 . The method of  claim 1 , wherein said base oil has an RBOT value of about 500 to about 1500 minutes.  
     
     
         12 . The method of  claim 5 , wherein said base oil has an RBOT value of about 500 to about 1500 minutes.  
     
     
         13 . A synthetic base oil comprising a mixture of monoalkylated and polyalkylated naphthalenes wherein the improvement comprises said synthetic base oil containing at least 20 wt % of an alkylated naphthalene selected from the group consisting of a compound or mixture of compounds of the following formula (I):  
       
         
           
           
               
               
           
         
         wherein R 1  and R 2  are H, methyl, ethyl, n-propyl, n-butyl, or t-butyl;  
         R 3  and R 4  are an alkyl group having from about 6 to about 24 carbon atoms;  
         x is from 0 to about 2; and  
         y is from 0 to about 4;  
         with the proviso that at least one of R 1  and R 2  is other than H, and at least one of x and y is other than 0.  
       
     
     
         14 . The synthetic base oil of  13  wherein at least one of R 1  and R 2  is hydrogen.  
     
     
         15 . The synthetic base oil of  claim 14  wherein at least one of R 1  and R 2  is methyl.