Continuous production of DMAEA quaternary salts
The invention provides a method of continuously producing high quality quaternized N,N-dialkylaminoethyl (meth)acrylates (DMAEA.MCQ) that has a long shelf life and which is stable in water. The method involves placing starting materials into a continuously stirred tank reactor in the presence of less than 6% water. This low amount of water causes two liquid phases to form and prevents unwanted side reactions. The denser liquid phase contains DMAEA.MCQ and the lighter phase contains the starting materials. Liquid from the denser phase is removed from a position where little of the lighter phase has been mixed in. The removed liquid then has any last traces of the starting materials reacted into DMAEA.MCQ and strips away any starting materials with a gas flow. The resulting liquid is high purity DMAEA.MCQ. Water can then safely be added to ease in the transport and use of the produced DMAEA.MCQ.
1. A method of continuously producing QAP comprising the steps of:
continuously feeding reactants into a CSTR, the reactants comprising TAS, water, and an alkylating agent;
maintaining conditions in the CSTR such that the pressure in the CSTR remains at 30-100 psi and also such that two distinct liquid phases form, a dense phase comprising more than 80% QAP and less than 20% water, and a light phase, present at greater than about 5 wt.% of the reaction mixture, comprising TAS, and alkylating agent, the dense phase being positioned below the light phase;
not allowing the water content of the CSTR to exceed 16% of the reactants continuously added to the CSTR; and
separating TAS from QAP within the CSTR while the TAS is reacting with the alkylating agent by continuously removing dense phase liquid from the CSTR, wherein the reactants are fed into the reactor from above the light phase, wherein the reactants form the QAP in the light phase, wherein the produced QAP migrates down into the dense phase, wherein at least a portion of the dense phase undergoes lower shear forces than the shear forces present in the light phase, and wherein the removed dense phase comprises more ppm of QAP than ppm of impurities, said impurities comprising unquaternized amines and acrylic acid, wherein the produced QAP has less than 300 ppm of TAS within it.
2. The method of claim 1 wherein the TAS is selected from the group consisting of DMAEA, any n,n-dialkylaminoalkyl (meth)acrylates, (meth)acrylamides, and any combination thereof.
3. The method of claim 1 wherein QAP produced is DMAEA.MCQ.
4. The method of claim 1 in which the alkylating group is selected from the group consisting of: methyl chloride, benzyl chloride, cetyl chloride, dimethyls sulfate, and any other commonly known alkylating agent, and any combination thereof.
5. The method of claim 1 in which the dense second phase is removed from the CSTR from the bottom of the CSTR.
6. The method of claim 1 in which additional reaction of residual TAS in the removed dense phase liquid is facilitated by reacting it in a plug flow reactor.
7. The method of claim 1 in which additional reaction of residual TAS in the removed dense phase liquid is facilitated by adding additional alkylating agent.
8. The method of claim 1 in which the alkylating agent is removed by purging the dense phase liquid with a gas flow.
9. The method of claim 1 in which the alkylating agent is removed by passing it through a stripping column.
10. The method of claim 1 in which the alkylating agent is removed by passing it into the top of a stripping column and passing a gas into the bottom of the stripping column, the gas selected from the list consisting of air, nitrogen, and any combination thereof.
11. The method of claim 1 in which the temperature in the CSTR is maintained at between 40-60 ° C.
12. The method of claim 1 in which the residence time in the CSTR ranges between 30-120 minutes.
13. The method of claim 1 in which the ratio of light first phase to dense phase is maintained at between 1:1 and 1:20.
14. The method of claim 1 in which the dense phase liquid is removed from the bottom of the CSTR at a location in which shear induced mixing of TAS and QAP is low relative to other locations within the CSTR.
15. The method of claim 1 further comprising the step of adding BHT and copper to the produced QAP.
16. The method of claim 15 further comprising the step of adding MEHQ to the produced QAP.
17. The method of claim 1 further comprising the steps of:
facilitating the reaction of any residual TAS in the dense phase liquid;
stripping the alkylating agent from the dense phase liquid; and
adding water to the dense phase liquid to obtain desired physical properties.