Method for making base oil with enhanced color stability

Abstract

A method for making a base oil having enhanced color stability and the base oil prepared therefrom are disclosed. The method comprises adding a phenyl benzotriazole compound to a base oil composition to form a color-stabilized base oil composition. In some cases, the phenyl benzotriazole compound has the structural formula (I): wherein, R and R′ are independently one or more substituents selected from hydrogen, substituted and unsubstituted alkyl, substituted and unsubstituted cycloalkyl, substituted and unsubstituted alkoxy, substituted and unsubstituted carboxyl, or a combination thereof, with the proviso that at least one of R and R′ is a non-hydrogen substituent.

What is claimed is: 
     
         1 . A method for improving the color stability of a base oil, the method comprising
 adding a phenyl benzotriazole compound to a base oil composition to form a color-stabilized base oil composition.   
     
     
         2 . The method of  claim 1 , wherein the color stability improvement is characterized by a reduction in the change in Saybolt color value over time for the color-stabilized base oil composition during exposure to UV radiation as compared with the change in Saybolt color value over the same time period and under the same UV exposure conditions for the same base oil composition that is not color-stabilized by the addition of the phenyl benzotriazole compound. 
     
     
         3 . The method of  claim 2 , wherein the change in Saybolt color value over a time period of 24 hrs for the color-stabilized base oil composition during exposure to UV radiation is less than about 50%, or 40% or 30%, or 20%, or 10%, or 5% of the change in Saybolt color value over the same time period and under the same UV exposure conditions for the same base oil composition that is not color-stabilized by the addition of the phenyl benzotriazole compound. 
     
     
         4 . The method of  claim 1 , wherein the phenyl benzotriazole compound has the structural formula (I): 
       
         
           
           
               
               
           
         
       
       wherein,
 R and R′ are independently one or more substituents selected from hydrogen, substituted and unsubstituted alkyl, substituted and unsubstituted cycloalkyl, substituted and unsubstituted alkoxy, substituted and unsubstituted carboxyl, or a combination thereof, with the proviso that at least one of R and R′ is a non-hydrogen substituent. 
 
     
     
         5 . The method of  claim 4 , wherein R and R′ are independently one or more substituents selected from hydrogen, substituted and unsubstituted C 1 -C 20 -alkyl, substituted and unsubstituted C 1 -C 20 -cycloalkyl, substituted and unsubstituted C 1 -C 20 -alkoxy, substituted and unsubstituted C 1 -C 20 -carboxyl, and combinations thereof. 
     
     
         6 . The method of  claim 4 , wherein R and R′ are independently one or more substituents selected from substituted and unsubstituted C 1 -C 20 -alkyl groups. 
     
     
         7 . The method of  claim 4 , wherein R and R′ are independently one or more substituents that are substituted with one or more substituents independently selected from C 1-6 -alkyl, hydroxyl, C 1-6 -alkoxy, C 1-6 -carboxyl, or a combination thereof. 
     
     
         8 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from
 2-(2-Hydroxy-5-methylphenyl)benzotriazole, 2-(2-Hydroxy-5-ethylphenyl)benzotriazole,   2-(2-Hydroxy-5-propylphenyl)benzotriazole, 2-(2-Hydroxy-5-butylphenyl)benzotriazole,   2-(2-Hydroxy-5-pentylphenyl)benzotriazole, 2-(2-Hydroxy-5-hexylphenyl)benzotriazole,   2-(2-Hydroxy-5-heptylphenyl)benzotriazole, 2-(2-Hydroxy-5-octylphenyl)benzotriazole,   2-(2-Hydroxy-5-nonylphenyl)benzotriazole, 2-(2-Hydroxy-5-decylphenyl)benzotriazole,   2-(2-Hydroxy-5-undecylphenyl)benzotriazole, 2-(2-Hydroxy-5-dodecylphenyl)benzotriazole, or a combination thereof.   
     
     
         9 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from
 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-methylphenol, 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-ethylphenol,   2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-propylphenol, 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-butylphenol,   2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-pentylphenol, 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-hexylphenol,   2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-heptyl phenol, 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-octyl phenol,   2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-nonylphenol, 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-decylphenol,   2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-undecylphenol, 2-(2H-Benzotriazol-2-yl)-6-dodecyl-4-dodecylphenol, or a combination thereof.   
     
     
         10 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from
 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-methylphenol, 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-ethylphenol,   2-(2H-Benzotriazol-2-yl)-6-undecyl-4-propylphenol, 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-butylphenol,   2-(2H-Benzotriazol-2-yl)-6-undecyl-4-pentylphenol, 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-hexylphenol,   2-(2H-Benzotriazol-2-yl)-6-undecyl-4-heptylphenol, 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-octylphenol,   2-(2H-Benzotriazol-2-yl)-6-undecyl-4-nonylphenol, 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-decylphenol,   2-(2H-Benzotriazol-2-yl)-6-undecyl-4-undecylphenol, 2-(2H-Benzotriazol-2-yl)-6-undecyl-4-dodecylphenol, or a combination thereof.   
     
     
         11 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from
 2-(2H-Benzotriazol-2-yl)-6-decyl-4-methylphenol, 2-(2H-Benzotriazol-2-yl)-6-decyl-4-ethylphenol,   2-(2H-Benzotriazol-2-yl)-6-decyl-4-propylphenol, 2-(2H-Benzotriazol-2-yl)-6-decyl-4-butylphenol,   2-(2H-Benzotriazol-2-yl)-6-decyl-4-pentyl phenol, 2-(2H-Benzotriazol-2-yl)-6-decyl-4-hexyl phenol,   2-(2H-Benzotriazol-2-yl)-6-decyl-4-heptylphenol, 2-(2H-Benzotriazol-2-yl)-6-decyl-4-octylphenol,   2-(2H-Benzotriazol-2-yl)-6-decyl-4-nonylphenol, 2-(2H-Benzotriazol-2-yl)-6-decyl-4-decylphenol,   2-(2H-Benzotriazol-2-yl)-6-decyl-4-undecylphenol, 2-(2H-Benzotriazol-2-yl)-6-decyl-4-dodecylphenol, or a combination thereof.   
     
     
         12 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from
 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-methylphenol, 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-ethylphenol,   2-(2H-Benzotriazol-2-yl)-6-nonyl-4-propylphenol, 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-butylphenol,   2-(2H-Benzotriazol-2-yl)-6-nonyl-4-pentylphenol, 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-hexylphenol,   2-(2H-Benzotriazol-2-yl)-6-nonyl-4-heptylphenol, 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-octylphenol,   2-(2H-Benzotriazol-2-yl)-6-nonyl-4-nonylphenol, 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-decylphenol,   2-(2H-Benzotriazol-2-yl)-6-nonyl-4-undecylphenol, 2-(2H-Benzotriazol-2-yl)-6-nonyl-4-dodecylphenol, or a combination thereof.   
     
     
         13 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from 2-(2H-Benzotriazol-2-yl)-4,6-di-tert-propylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-methylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-ethylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-propylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-butylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-pentylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-hexylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-heptylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-octylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-nonylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-decylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-undecylphenol, 2-(2H-Benzotriazol-2-yl)-6-tert-propyl-4-dodecylphenol, or a combination thereof. 
     
     
         14 . The method of  claim 4 , wherein the phenyl benzotriazole compound is selected from 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-methylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-ethylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-propylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-butylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-pentylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-hexylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-heptylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-octylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-nonylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-decylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-undecylphenol, 2-(2H-Benzotriazol-2-yl)-4-tert-propyl-6-dodecylphenol, or a combination thereof. 
     
     
         15 . The method of  claim 1 , wherein the base oil is Group I or II base oil. 
     
     
         16 . A color-stabilized base oil composition made according to the method of  claim 1 , the color-stabilized base oil composition having improved color stability by comparison to the base oil composition that is not color-stabilized by the addition of the phenyl benzotriazole compound. 
     
     
         17 . The color-stabilized base oil composition of  claim 16 , wherein the color stability improvement is characterized by a reduction in the change in Saybolt color value over time for the color-stabilized base oil composition during exposure to UV radiation as compared with the change in Saybolt color value over the same time period and under the same UV exposure conditions for the same base oil composition that is not color-stabilized by the addition of the phenyl benzotriazole compound. 
     
     
         18 . The color-stabilized base oil composition of  claim 17 , wherein the change in Saybolt color value over a time period of 24 hrs for the color-stabilized base oil composition during exposure to UV radiation is less than about 50%, or 40% or 30%, or 20%, or 10%, or 5% of the change in Saybolt color value over the same time period and under the same UV exposure conditions for the same base oil composition that is not color-stabilized by the addition of the phenyl benzotriazole compound. 
     
     
         19 . A color-stabilized base oil composition made according to the method of  claim 4 , the color-stabilized base oil composition having improved color stability by comparison to the base oil composition that is not color-stabilized by the addition of the phenyl benzotriazole compound having the structural formula (I).