Synthesis of onium hydroxides from onium salts

A process for preparing an onium hydroxide from a corresponding onium salt comprising:

• (A) providing an electrochemical cell comprising a cathode, an anode, a cation selective membrane and a bipolar membrane, the bipolar membrane having an anion selective side facing the anode and a cation selective side facing the cathode, wherein the cation selective membrane is positioned between the cathode and the bipolar membrane, and the bipolar membrane is positioned between the cation selective membrane and the anode, thereby defining a feed compartment between the cation selective membrane and the bipolar membrane, a recovery compartment between the cation selective membrane and the cathode, and a water compartment between the bipolar membrane and the anode;
• (B) charging a solution comprising the onium salt to the feed compartment;
• (C) charging a liquid electrolyte to the other compartments;
• (D) passing a current through the electrochemical cell to produce the onium hydroxide in the recovery compartment;
• and
• (E) recovering the onium hydroxide from the recovery compartment.

A process for purifying an onium hydroxide solution comprising:

• (A) providing an electrochemical cell comprising a cathode, an anode, a cation selective and a bipolar membrane, the bipolar membrane having an anion selective side facing the anode and a cation selective side facing the cathode, wherein the cation selective membrane is positioned between the cathode and the bipolar membrane, and the bipolar membrane is positioned between the cation selective membrane and the anode, thereby defining a feed compartment between the cation selective membrane and the bipolar membrane, a recovery compartment between the cation selective membrane and the cathode, and a water compartment between the bipolar membrane and the anode;
• (B) charging the onium hydroxide solution to the feed compartment;
• (C) charging a liquid electrolyte to the other compartments;
• (D) passing a current through the electrochemical cell to regenerate onium hydroxide in the recovery compartment;
• and
• (E) recovering a purified onium hydroxide solution from the recovery compartment.

A process for preparing tetramethylammonium hydroxide from a tetramethylammonium salt and for purifying tetramethylammonium hydroxide comprising:

• (A) providing an electrochemical cell comprising a cathode, an anode, a divider and a bipolar membrane, the bipolar membrane having an anion selective side facing the anode and a cation selective side facing the cathode, wherein the divider is positioned between the cathode and the bipolar membrane, and the bipolar membrane is positioned between the divider and the anode, thereby defining a feed compartment between the divider and the bipolar membrane, a recovery compartment between the divider and the cathode, and a water compartment between the bipolar membrane and the anode;
• (B) charging a solution comprising at least one of the tetramethylammonium salt and the tetramethylammonium hydroxide to be purified to the feed compartment;
• (C) charging a liquid electrolyte to the other compartments;
• (D) passing a current through the electrochemical cell to produce the tetramethylammonium hydroxide in the recovery compartment;
• and
• (E) recovering the tetramethylammonium hydroxide from the recovery compartment.