Methods for making carboxylated cellulosic fibers

Abstract

Methods for making carboxylated cellulosic fibers using the N-halo hindered cyclic amine compounds. N-halo hindered cyclic amine compounds react with a secondary oxidizing agent to provide a primary oxidizing agent that reacts with cellulosic fibers to provide carboxylated cellulosic fibers.

1 . A method for making carboxylated cellulosic fibers, comprising: 
 reacting an N-halo hindered cyclic amine compound with secondary oxidizing agent to provide a primary oxidizing agent; and    contacting the primary oxidizing agent with cellulosic fibers to provide carboxylated cellulosic fibers.    
     
     
         2 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound comprises a cyclic amine compound that is fully alkylated at the carbon atoms adjacent to the amino nitrogen atom.  
     
     
         3 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound comprises a cyclic amine compound having from 4 to 8 atoms in the ring.  
     
     
         4 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound comprises a five-membered ring compound.  
     
     
         5 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound comprises a six-membered ring compound.  
     
     
         6 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; X is oxygen or sulfur; R 5  is at least one of hydrogen, C1-C12 straight-chain or branched alkyl or alkoxy, aryl, aryloxy, benzyl, 2-dioxanyl, dialkyl ether, alkyl polyether, or hydroxyalkyl; and A is at least one of chloro or bromo.  
       
     
     
         7 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; R 6  is at least one of C1-C6 straight-chain or branched alkyl; R 7  is at least one of hydrogen, C1-C8 straight-chain or branched alkyl, phenyl, carbamoyl, alkyl carbamoyl, phenyl carbamoyl, or C1-C8 acyl; and A is at least one of chloro or bromo.  
       
     
     
         8 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; X is at least one of oxygen, sulfur, NH, alkylamino, dialkylamino, NOH, or NOR 10 , wherein R 10  is a C1-C6 straight-chain or branched alkyl; and A is at least one of chloro or bromo.  
       
     
     
         9 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; X is at least one of oxygen, sulfur, N—R 10 , or N—C(═O)—R 10 , wherein R 10  is a C1-C6 straight-chain or branched alkyl; and A is at least one of chloro or bromo.  
       
     
     
         10 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; and A is at least one of chloro or bromo.  
       
     
     
         11 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; X is at least one of methylene, oxygen, sulfur, or alkylamino; R 8  and R 9  are independently at least one of C1-C6 straight-chain or branched alkyl groups, or R 8  and R 9  taken together can form a five- or six-membered ring; and A is at least one of chloro or bromo.  
       
     
     
         12 . The method of  claim 1 , wherein the N-halo hindered cyclic amine compound has the structure:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; X is at least one of methylene, oxygen, sulfur, NH, N—R 10 , or N—C(═O)—R 10 , wherein R 10  is a C1-C6 straight-chain or branched alkyl; and A is at least one of chloro or bromo.  
       
     
     
         13 . The method of  claim 1 , wherein the primary oxidizing agent is at least one of chlorine dioxide, a peracid, hydrogen peroxide, ozone, or a hypohalite.  
     
     
         14 . The method of  claim 13 , wherein the hypohalite comprises sodium hypochlorite.  
     
     
         15 . The method of  claim 1 , wherein the carboxylated fibers comprises C-6 carboxyl groups.  
     
     
         16 . The method of  claim 1  further comprising stabilizing the carboxylated fibers.  
     
     
         17 . The method of  claim 16 , wherein stabilizing the carboxylated fibers comprises treating the carboxylated fibers with a reducing agent.  
     
     
         18 . The method of  claim 17 , wherein the reducing agent is at least one of sodium borohydride, lithium borohydride, or sodium cyanoborohydride.  
     
     
         19 . The method of  claim 16 , wherein stabilizing the carboxylated fibers comprises treating the carboxylated fibers with an oxidizing agent.  
     
     
         20 . The method of  claim 19 , wherein the oxidizing agent is at least one of sodium chlorite, chlorine dioxide, or hydrogen peroxide.  
     
     
         21 . A method for making stable carboxylated cellulosic fibers, comprising: 
 reacting an N-halo hindered cyclic amine compound with secondary oxidizing agent to provide a primary oxidizing agent;    contacting the primary oxidizing agent with cellulosic fibers to provide carboxylated cellulosic fibers; and    treating the carboxylated cellulosic fibers with a stabilizing agent to provide stabilized carboxylated cellulosic fibers.    
     
     
         22 . The method of  claim 21 , wherein the N-halo hindered cyclic amine compound is an N-chloro-2,2,6,6-tetramethyl-4-piperidone ketal.  
     
     
         23 . The method of  claim 21 , wherein the N-halo hindered cyclic amine compound is N-chloro-2,2,6,6-tetramethyl-4-piperidone ethylene glycol ketal.  
     
     
         24 . The method of  claim 21 , wherein the secondary oxidizing agent is at least one of chlorine dioxide, a peracid, hydrogen peroxide, or ozone.  
     
     
         25 . The method of  claim 21 , wherein the stabilizing agent is a chlorite.  
     
     
         26 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein X is oxygen or sulfur;  
         R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl;  
         R 5  is at least one of hydrogen, C1-C12 straight-chain or branched alkyl or alkoxy, aryl, aryloxy, benzyl, 2-dioxanyl, dialkyl ether, alkyl polyether, or hydroxyalkyl; and  
         A is at least one of chloro or bromo.  
       
     
     
         27 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl;  
         R 6  is at least one of C1-C6 straight-chain or branched alkyl;  
         R 7  is at least one of hydrogen, C1-C8 straight-chain or branched alkyl, phenyl, carbamoyl, alkyl carbamoyl, phenyl carbamoyl, or C1-C8 acyl; and  
         A is at least one of chloro or bromo.  
       
     
     
         28 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein X is at least one of oxygen, sulfur, NH, alkylamino, dialkylamino, NOH, or NOR 10 , wherein R 10  is a C1-C6 straight-chain or branched alkyl;  
         R 1 -R 4  are independently at least one of C1 —C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; and  
         A is at least one of chloro or bromo.  
       
     
     
         29 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein X is at least one of oxygen, sulfur, N—R 10 , or N—C(═O)—R 10 , wherein R 10  is a C1-C6 straight-chain or branched alkyl;  
         R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; and  
         A is at least one of chloro or bromo.  
       
     
     
         30 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; and  
         A is at least one of chloro or bromo.  
       
     
     
         31 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein X is at least one of methylene, oxygen, sulfur, or alkylamino;  
         R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl;  
         R 8  and R 9  are independently at least one of C1-C6 straight-chain or branched alkyl groups, or R 8  and R 9  taken together can form a five- or six-membered ring; and  
         A is at least one of chloro or bromo.  
       
     
     
         32 . A compound having the formula:  
       
         
           
           
               
               
           
         
         wherein X is at least one of methylene, oxygen, sulfur, NH, N—R 10 , or N—C(═O)—R 10 , wherein R 10  is a C1-C6 straight-chain or branched alkyl;  
         R 1 -R 4  are independently at least one of C1-C6 straight-chain or branched alkyl, or R 1  and R 2  taken together can form a five- or six-carbon cycloalkyl, or R 3  and R 4  taken together can form a five- or six-carbon cycloalkyl; and  
         A is at least one of chloro or bromo.