WO2009002761A1 - A method for making n-2,3-dibromopropyl-4,5-dibromohexahydrophthalimide - Google Patents

Abstract

The present invention relates to process technology suitable for producing, on a commercial scale, N-2,3-dibromopropyl-4,5-dibromohexahydrophthalimide formula (1).

Description

A METHOD FOR MAKING

N-2,3-DlBROMOPROPYL-4,5-DlBROMOHEXAHYDROPHTHALIMIDE

FILED OF THE INVENTION

[0001] The present invention relates to process technology suitable for producing, on a commercial scale, N-2,3-dibromopropyl-4,5-dibromohexahydrophthalimide. BACKGROUND OF THE INVENTION

[0002] Over the years a number of brominated flame retardants have been developed for use in the polymer industry. These materials are blended into polymers that are used in a number of consumer goods such as the plastic cases of computers, insulation, television consoles, etc. Generally, however, even with the availability of a wide range of flame retardants, the polymer industry has increasingly demanded more and better flame retardants. Thus, there is continually a need in the art for flame retardant compositions and methods of making them. [0003] This invention provides process technology that is suitable for producing N-2,3- dibromopropyl-4,5-dibromohexahydrophthalimide ("tetraBr-THPAI") on a commercial scale with good performance characteristics. The process technology of this invention not only makes possible the production of tetraBr-THPAI in good yields under practical reaction conditions, but can also minimize, or in some embodiments avoid, the co-production of reactive impurities in the final product. The minimization, or in some embodiments elimination, of reactive impurities in the final tetraBr-THPAI product is one desirable feature of the present invention because these reactive impurities can adversely impact the performance of the tetraBr-THPAI product. For example, these impurities can release hydrogen bromide ("HBr") at lower temperatures than the tetraBr-THPAI product, which can lead to polymer degradation during the processing of the polymer and flame retardant. SUMMARY OF THE INVENTION [0004] In one embodiment, the present invention relates to a process comprising:

A) heating a mixture containing cis-l,2,3,6-tetrahydrophthalimide ("THPI"), a base, preferably a metal carbonate, an allyl-containing species such as an allyl halide, an organic solvent which is preferably inert in the subsequent bromination step, and optionally a phase transfer catalyst, e.g. quaternary alkyl and/or aryl ammonium phase transfer catalysts, crown ethers, substituted amines, and combinations thereof, to one or more temperatures in the range of from about 3O⁰C to about 300⁰C thereby forming a reaction mass containing N-allyl-cis-l,2,3,6-tetrahydrophthalimide ("THPAI");

B) purifying the reaction mass thereby producing a purified THPAI reaction mass; C) brominating the purified THPAI reaction mass at one or more temperatures in the range of from about -4O⁰C to about HO⁰C thereby forming a first product reaction mass containing tetraBr-THPAI and one or more brominated byproducts; and,

D) removing at least a portion, preferably substantially all, of any residual free bromine from the first product reaction mass thereby forming a second product reaction mass;

E) optionally, treating the second product reaction mass to selectively convert at least a portion, preferably substantially all, of any reactive brominated byproducts into less reactive species thereby forming a third product reaction mass;

F) isolating at least a portion, preferably substantially all, of the tetraBr-THPAI product in the third product reaction mass through i) crystallization, ii) precipitation, iii) solvent evaporation such as through the use a devolatization extruder, or any combination of i)-iii); and optionally

G) washing and drying the isolated tetraBr-THPAI product if it was isolated through crystallization or precipitation.

[0005] In preferred embodiments, especially when the tetraBr-THPAI product in the third reaction mass is isolated through i) crystallization, and/or ii) precipitation in step F), optional step G) is also used. [0006] In a second embodiment, the present invention relates to a process comprising:

A) heating in a reactor a mixture containing THPI, sodium carbonate, allyl chloride, an organic solvent, preferably monochlorobenzene ("MCB"), and tetrabutylammonium bromide ("TBAB") phase transfer catalyst to one or more temperatures in the range of from about 6O⁰C to 25O⁰C wherein the pressure of the reactor is maintained at one or more pressures up to the pressure rating of the reactor thereby forming a reaction mass containing at least THPAI and one or more impurities;

B) purifying the reaction mass thereby producing a purified THPAI reaction mass;

C) brominating the purified THPAI reaction mass at one or more temperatures in the range of from about -4O⁰C to about HO⁰C thereby forming a first product reaction mass containing tetraBr-THPAI and one or more brominated byproducts;

D) removing at least a portion, preferably substantially all, of any residual free bromine from the first product reaction mass, preferably by contacting the first product reaction mass with aqueous sodium sulfite, sodium bisulfite, or sulfurous acid, thereby forming a second product reaction mass, in preferred embodiments comprising residual bromine, aqueous sodium sulfite, sodium bulfite, and/or sulfurous acid;

E) treating the second product reaction mass with aqueous sodium carbonate at one or more temperatures in the range of from about 1O⁰C to 12O⁰C to selectively convert at least a portion, preferably substantially all, of any reactive brominated byproducts into less reactive species thereby forming a third product reaction mass;

F) isolating at least a portion, preferably substantially all, of the tetraBr-THPAI product in the third reaction mass through i) crystallization, ii) precipitation, iii) solvent evaporation such as through the use a devolatization extruder, or any combination of i)-iii); and optionally,

G) washing and drying the isolated tetraBr-THPAI product if it was isolated through crystallization or precipitation,

[0007] In some embodiments, when conducting step B) of the present invention, described above, it is preferable to: 1) remove at least a portion, preferably substantially all, of any inorganic and organic salts from the reaction mass by dissolving the salts into water and then phase separating the THPAI-containing organic phase from the water-containing aqueous phase; 2) to wash the resultant THPAI-containing organic phase one or more times with water (separating the organic phase from the aqueous phase afterwards) to further remove at least a portion, preferably substantially all, of any salts remaining after 1), thereby forming the purified THPAI reaction mass; and/or 3) to remove at least a portion of, preferably substantial all, of any excess allyl-containing species from the purified THPAI reaction mass prior to step C), i.e. brominating the purified THPAI reaction mass; and/or optionally 4) to remove at least a portion, preferably substantially all, of any "heavies" from the purified THPAI reaction mass prior to step C), i.e. brominating the purified THPAI reaction mass. By heavies, it is meant reaction by-products having a boiling point higher than the THPAI. [0008] In some embodiments, when conducting A), only a portion of the allyl-containing species is fed with the other reactants prior to heating, and, once the reactor contents reach the desired temperature, in some embodiments one or more temperatures in the range of from about 30⁰C to about 300⁰C, the remaining portion of the allyl-containing species is fed in over time, preferably at a constant rate. It should be noted that the reaction(s) occurring in A) may be exothermic, and thus the heat removal capabilities of the reactor/vessel to which the allyl-containing species is being fed should be taken into account when feeding the allyl- containing species. For example, in some embodiments, feeding the allyl-containing species at a rapid rate may not be feasible due to limited heat removal capabilities of the reactor/vessel to which the allyl-containing species is being fed. In these embodiments, the rate at which the allyl-containing species is fed can be adjusted to assist with maintaining the temperature at one or more temperatures within the range discussed above. [0009] In some embodiments, when conducting B), the at least a portion of the excess allyl- containing species removed is removed by flashing or distillation, with or without a portion of the organic solvent, preferably after quenching and washing the reaction mass with water. [0010] In some embodiments, when conducting B), the at least a portion of heavies are removed by distilling or flashing at least a portion, preferably substantially all, of the organic solvent and THPAI overhead, preferably after quenching and washing the reaction mass with water and removal of at least a portion of any excess allyl-containing species from the purified THPAI reaction mass have been accomplished.

[0011] In some embodiments, when conducting B), and when the organic solvent is methyl chlorobenzene ("MCB"), the allyl-containing species is allyl chloride, the at least a portion of heavies removed can be separated by distilling or flashing substantially all of the MCB, THPAI, and any remaining allyl-chloride overhead, and at least a portion, preferably substantially all, of the allyl-chloride, if any is present, can then be removed from the overhead via flashing or distillation.

[0012] In some embodiments, when conducting E), the pH is kept at one or more pH's in the range of from about 3 to about 11 so that a portion of any byproducts react at an appreciable rate but the tetraBr-THPAI decomposition rate is small.

[0013] In another embodiment, the present invention relates to a process for forming a tetraBr-THPAI product from THPI, sodium carbonate, MCB, TBAB, and allyl chloride comprising:

A) introducing into a reactor THPI₅ sodium carbonate, MCB, TBAB, and a portion of the allyl chloride;

B) heating the reactor contents to one or more temperatures in the range of from about 8O⁰C to about 25O⁰C;

C) introducing into the reactor the remainder of the allyl chloride, preferably over time thereby forming a reaction mass

D) cooling the reaction mass to a temperature in the range of from about -10⁰C to about 100⁰C thereby forming a cooled reaction mass;

E) removing at least a portion, preferably substantially all, of any inorganic and organic salts from the cooled reaction mass by a) quenching the cooled reaction mass with water, b) recovering the organic phase from a) via phase separation; and optionally repeating one or more times the following: c) washing the organic phase recovered in b) with water and recovering the organic phase from c) via phase separation techniques;

F) removing at least a portion, preferably substantially all of any excess allyl chloride in the recovered organic phase from E) via flashing or distillation thereby producing a THPAI reaction mass;

G) brominating the THPAl reaction mass at one or more temperatures in the range of from about -4O⁰C to about 110⁰C thereby forming a first product reaction mass containing tetraBr-THPAI and one or more brominated byproducts;

H) removing at least a portion, preferably substantially all, of any residual free bromine from the first product reaction mass by contacting the first product reaction mass with aqueous sodium sulfite thereby forming a second product reaction mass containing residual bromine and aqueous sodium sulfite, sodium bisulfite, and/or sulfurous acid;

I) treating the second product reaction mass with aqueous sodium carbonate at one or more temperatures in the range of from about 3O⁰C to 100⁰C while maintaining the pH of the second product reaction mass at pH in the range of from about 4 to about 10.5, preferably in the range of from about 7 and about 9, thereby forming a third product reaction mass

H) isolating at least a portion, preferably substantially all, of the tetraBr-THPAI product in the third reaction mass via precipitation using one or more aliphatic hydrocarbons;

I) recovering at least a portion, preferably substantially all, of tetraBr-THPAI product via, for example, filtration; and

J) washing and drying the isolated tetraBr-THPAI product.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The inventors hereof believe, while not wishing to be bound by theory, that the production of tetraBr-THPAI products in the present invention can be described by the following two-step reaction scheme: Step 1, Alkylation:

cis-],2,3,6-tetrahydrophthalimide "THPAI" "THPI" + Base-HX

Step 2, Bromination: solvent

tetraBr-THPAI

Alkylation Reaction

[0015] In the practice of the present invention, a reaction mass containing N-allyl-cis-1 ,2,3,6- tetrahydrophthalimide ("THPAI") is formed by introducing into a reactor cis- 1,2,3,6- tetrahydrophthalimide ("THPI"), a base, an allyl-containing species such as an allyl halide, an organic solvent, and optionally a phase transfer catalyst, and the contents of the reactor are maintained at one or more temperatures in the range of from about 30⁰C to about 300⁰C. The reaction mass containing N-allyl-cis-1, 2,3,6-tetrahydrophthalimide ("THPAI") is principally formed by alkylation of the starting THPI with an allyl-containing species to which is attached a leaving group. While not wishing to be bound by theory, the inventors hereof believe that the general mechanism of the alkylation reaction likely involves 1) deprotonation or partial deprotonation of the acidic proton on the THPI by the base, e.g., the metal carbonate, and 2) the resultant species attacking the allyl-containing molecule to form THPAI plus the acid salt of the base. For the specific example where the base is sodium carbonate and the allyl-containing molecule is allyl chloride, the reaction would yield THPAI plus an equimolar mixture of sodium chloride and sodium bicarbonate. It should be noted that in the practice of the present invention it is useful to use a molar excess of base and allyl- containing species to drive the reaction to completion.

[0016] In the practice of the present invention it is also desirable to take steps and precautions to limit, preferably eliminate, water from the processes of the present invention even when using a non-nucleophilic base since the water and base will equilibrate to generate some amount of hydroxide ion, which is both basic and nucleophilic.

[0017] In the practice of the present invention the phase transfer catalyst increases reaction rates by solubilizing a greater portion of the base in the solution; in many cases the reaction rate is constrained because only a small portion of the base is present in solution. [0018] It should be noted that it is important in commercial operations to keep reaction rates high so that capital costs can be kept low (higher throughput for a given volume reactor). In balance with this is a desire to keep raw material costs low. For the alkylation reaction there is often a tradeoff when selecting which base to use and which allyl-containing species to use. Bases

[0019] The amount of base used in the practice of the present invention should generally be that amount of base capable of converting at least a portion, preferably substantially all, of the THPI to THPAI. Generally, the amount of base used is in the range of from about 0.45 to about 8.00 equivalents per equivalent of starting THPI, preferably in the range of from about 1.05 to 2.00 equivalents, more preferably in the range of from about 1.15 to 1.25 equivalents, all on the same basis. It should be noted that, while not wishing to be bound by theory, the inventors hereof believe that adding more than the stoichiometric requirement of base will oftentimes decrease reaction times but will also result in higher overall raw material costs, and this should be considered in some embodiments when selecting the amount of base to be used.

[0020] In the practice of the present invention it is desirable to choose a base that is non- nucleophilic or weakly nucleophilic. With nucleophilic bases, there is a potential competition between deprotonation of the THPI and ring opening of the imides (THPI and THPAI). The latter of these results in yield loss and may also lead to a poorer-performing product. [0021] Bases suitable for use herein can be selected from compounds such as, for example, potassium carbonate, sodium carbonate, and calcium carbonate, which are non-nucleophilic and have good basicity. Potassium carbonate is preferred from a reaction rate standpoint since it is a stronger base than sodium carbonate. However, sodium carbonate is preferred from an economic standpoint because it is cheaper than potassium carbonate. While not as effective from a reaction rate standpoint and somewhat less soluble than potassium carbonate, the rate of reaction when using sodium carbonate and/or sodium carbonate's solubility can be increased or enhanced through the use of a phase transfer catalyst.

[0022] From a process standpoint, calcium carbonate is the least preferred of the bases described above, even though it is cheaper than sodium carbonate. Some of the reasons, which can be overcome, why calcium carbonate is the least preferred include: (a) its use causes difficulties during the purification of the THPAI product; (b) it is nearly insoluble in water, and any solid calcium carbonate could lead to emulsions during the purification of the THPAI product; and (c) it is used in excess during the alkylation to drive the reaction to completion. To resolve the drawbacks of the use of calcium carbonate, the installation of filters or centrifuges can be used. Allyl-containinfi species

[0023] The amount of allyl-containing species used in the practice of the present invention is generally in the range of from about 0.80 equivalents to about 6.00 equivalents of allyl- containing species per equivalent of THPI, preferably in the range of from about 1.02 to about 1.50, and more preferably in the range of from about 1.10 to about 1.25, all on the same basis.

[0024] Allyl-containing species suitable for use herein can be selected from allyl halides, preferably allyl bromide or allyl chloride, allyl alcohol, allyl tosylate, and allyl mesylate. In preferred embodiments, the allyl-containing species is an allyl-halide. It should be noted that in regards to which allyl-containing species to use, there is a tradeoff between reactivity and pricing. For example, allyl bromide is more reactive but also more expensive than allyl chloride.

[0025] If the allyl-containing species is metered into the reactor, i.e. introduced into the reactor over time, it is preferred to first introduce at least a portion at ambient temperatures and then to introduce the remainder of the allyl-containing species once the reactor contents have reached the desired temperature. In these embodiments, it is preferred that the allyl- containing species is allyl chloride. Introducing the allyl-containing species in this manner is beneficial because i) the initial charge will help the reactor contents to reach reaction temperature more quickly and ii) the formation of byproducts derived from trace water in the solvent(s) and/or reactant(s) will be suppressed, in other words, if some fraction of the allyl- containing species is precharged, it presumably may act as a sacrificial agent to remove the water via conversion to allyl alcohol. As noted above, the presence of water can lead to the opening of the imide ring on the THPI during heatup which in turn leads to lower yields and/or product performance. It should be noted that allyl alcohol could also act as a nucleophile if deprotonated, but pre-charging some allyl chloride has been observed to provide for less impurities in the THPAI product. This may be due to allyl alcohol having a higher pK_athan water and thus being less reactive than water in attacking the imide ring. [0026] In some embodiments, substantially all of the allyl-containing species can be introduced into the reactor, and then the contents of the reactor vessel heated to the desired temperature or maintained at the desired temperature. It should be noted that proceeding in this manner is not always feasible, and consideration should be given to the heat removal capabilities of the reactor used. For example, if the heat removal capabilities of the reactor are not sufficient to maintain the temperature within the ranges discussed herein, operating the process of the present invention in this manner may not be advised, In these embodiments, one could charge as much of the allyl-containing species as possible without overcoming the heat removal capabilities of the reactor, and then introduce, piece wise or otherwise, the remainder of the allyl-containing species such that the temperature does not exceed the ranges discussed herein. Organic Solvent

[0027] The amount of organic solvent used in the practice of the present invention is generally in the range of from about 0.1 to about 20 volumes of organic solvent per volume of THPl charged, preferably in the range of from about 1.0 to about 10.0, more preferably in the range of from about 1.5 to about 2.5, on the same basis. More generally, when determining the amount of solvent to use consideration should be given to a) how thick the reaction slurry is and b) to overall reactor sizing. In the former, if the reaction mass is too thick to be stirred effectively, additional solvent should be added. In the latter, too much solvent leads to larger reactors and thus to greater capital requirements. If the THPI is soluble in the reaction solvent, generally less solvent will be required. If the THPI is added as a melt when at temperature even less solvent may be required.

[0028] The choice of which solvent(s) to use in the conversion of THPI to THPAI is largely guided by simplification of the process so long as the solvent(s) can easily be recycled. Non- limiting examples of suitable organic solvents include chlorobenzene, bromobenzene, benzene, ethers such as methyl t-butyl ether, and esters such as ethyl acetate. Chlorobenzene has been found to be a good solvent because its use leads to few byproducts during the THPI to THPAI reaction and because it is relatively unreactive towards bromine for the conversion of THPAI to tetraBr-THPAI. This allows for a "one pot" process with no need to change the solvent used between the two chemical steps. Phase Transfer Catalyst

[0029] The amount of phase transfer catalyst used herein is dependent upon a number of factors including, but not limited to, a) the specific base being used, b) the allyl-containing species used, c) the reaction temperature, and d) the heat removal capabilities of the reactor/vessel used. In general, the amount of phase transfer catalyst used in the practice of the present invention is in the range of from about 0.001 equivalents to about 1.00 equivalents of phase transfer catalyst per equivalent of THPI used, preferably in the range of from about 0.005 to about 0.020, more preferably in the range of from about 0.008 to about 0.016, on the same basis. It should be noted that a phase transfer catalyst is generally used herein to increase the reaction rate of the alkylation reaction.

[0030] It is desirable to select the phase transfer catalyst used herein based upon an analysis of productivity and ease of operation versus cost. Non-limiting examples of suitable phase transfer catalysts include crown ethers as well as quaternary ammonium salts such as TBAB and benzyl triethylammonium chloride. It should be noted that amines may be used in place of a standard phase transfer catalyst if there is a molar excess of allyl -containing species and the reaction temperature is sufficiently high, In that case, a phase transfer catalyst is generated in situ. For example, if allyl chloride is used as the allyl-containing species and tributylamine is used as a "phase transfer catalyst", the two may react to form tributylallylammonium chloride in situ by about 130⁰C, which can then serve as the phase transfer catalyst. Reaction Conditions

[0031] It is desirable to maintain reaction temperature during the alkylation reaction, i.e. step A), because at higher temperatures, reaction rates are higher, which result in higher throughput for a given volume of reaction mass, but at higher temperatures there is also the potential to form more byproducts which will result in lower yields and may impact final product performance. Thus, it is desirable to maintain the temperature of the reactor contents at one or more temperatures in the range of from about 30⁰C to about 300⁰C, preferably at one or more temperatures in the range of from about 75⁰C to about 200⁰C, preferably at one or more temperatures in the range of from about 11O⁰C to about 15O⁰C. [0032] Reaction pressure is also preferably controlled, especially with sodium carbonate as the base. Thus, it is desirable to maintain the pressure of the reactor such that the reaction mass is at or below its boiling point but certainly not more than the pressure rating of the reactor. Should the alkylation reaction be conducted in a completely sealed reactor, the pressure in that reactor may rise over the course of the alkylation reaction. This may be due to byproduct generation. For example, if sodium carbonate is used as the base sodium bicarbonate can be in equilibrium with sodium carbonate, any water, and carbon dioxide gases. Empirically the alkylation reaction can take tens of hours to reach completion when conducted in this manner. If the product gases are allowed to escape during the alkylation reaction through the use of, for example, a backpressure regulator or similar device, the alkylation reaction can take only a few hours. The differing effective reaction rates may be due to the removal of at least a portion of any carbon dioxide generated from the "system", i.e. reactor, in the latter case. Removal of CO₂ would drive the equilibrium towards sodium carbonate and away from sodium bicarbonate. Such a shift in equilibrium can effectively increase the amount of sodium carbonate available for reaction. Another possibility is that the byproduct sodium bicarbonate is encapsulating the remaining sodium carbonate reactant when the reaction is conducted in a sealed reactor. This would effectively limit the rate of transfer of sodium carbonate into the liquid phase thus slowing down the overall reaction. By driving the sodium bicarbonate to sodium carbonate, this encapsulation effect can be eliminated or at least significantly reduced.

[0033] It should be noted that that when conducting the alkylation at large scale, for example in a commercial operation, it is important to balance heat generation with the ability to remove heat from the reactor. For example, the alkylation reaction is exothermic by about 190 kJ/gmol of THPI charged when allyl chloride is the alkylating agent and sodium carbonate is the base, and if all of the raw materials are precharged and heat removal capabilities are not sufficient, it is possible for an unsafe "runaway" reaction to develop within the reactor. To mitigate this chance it is often preferable to feed or meter in one of the reactants over a period of time. If allyl bromide or allyl chloride serves as the allyl- containing species, it is preferred to meter that material because both are liquids and are thus easier to handle. In contrast, it would be more difficult to meter in solid THPI (melting point 131⁰C) or solid sodium carbonate (melting point 851⁰C). It should be noted that the THPI could be added as a melt, but this would require additional equipment to store it at or above its melting point, and thus is within the scope of the present invention but is not preferred. Purification and workup of THPAI Reaction Mass

[0034] It is desirable, although not required, to remove at least a portion, preferably substantially all, of any inorganic and/or organic salts from the reaction mass thereby forming a purified THPAI reaction mass, sometimes referred to herein as the THPAI intermediate, following the alkylation reaction. Since the majority of these salts are typically soluble in water, this can be accomplished by quenching the reaction mass with water and then recovering the organic phase, i.e. the purified THPAI reaction mass, via phase separation techniques. It is desirable to conduct the quench at temperatures in the range of about -5⁰C to about 100⁰C so that the temperature is above the freezing point of the salt-containing aqueous phase but low enough so that there would not be substantial decomposition of the THPAI. If higher temperatures are contemplated, experiments should be conducted to verify that the THPAI will not decompose which in turn could lead to lower yields and/or poorer performance of the final product. For the specific example where sodium carbonate serves as the base and MCB as the solvent, there is some utility in conducting the quench step at temperatures in the range of about 40⁰C to about 60°C due to the higher solubility of the byproduct salts at these temperatures. Conducting the quenching at these temperatures helps to reduce the wastes in the process and it also allows the aqueous phase to be the denser of the two liquid phases present, which has the advantage of allowing the aqueous phase to be removed from the organic prior to doing any further purification. As a result, one less tank is required in the process as the THPAI-containing organic phase can be quenched and washed in a single vessel; if the organic phase were denser, the organic phase would need to be cut into another vessel prior to conducting any further purification steps such as the washing step. It should be noted that the quenching, and any further purification steps, discussed below, may be conducted at temperatures higher than about 6O⁰C for the specific system mentioned, but consideration should be given to minimize the decomposition of THPAI. [0035] After the first quenching, the recovered organic phase can be subjected to further purification steps such as water washing. For example, the organic phase recovered from the quenching of the reaction mass can be washed with water again and the organic phase from this water washing step can again be recovered via phase separation. This water washing of the organic phase can be conducted one or more times in the practice of the present invention until the desired amount of impurities are removed from the organic phase. It should be noted that it is within the scope of the present invention that the aqueous phase recovered via the phase separation during the washing of the organic phase and/or quenching of the reaction mass can be recovered and used as wash water and or quenching agents in further purification steps or production runs.

[0036] After quenching and optional washing, it is desirable to remove at least a portion, preferably substantially all, of any remaining allyl-containing species from the recovered organic phase. If allyl-containing species are allowed to proceed through the process, bromine utilizations will suffer, e.g. the allyl-containing species will react with bromine just like the THPAI will. Final product purity/performance may also suffer if excessive amounts of allyl-containing species remain because of additional impurities that can be generated. The method used to separate the allyl-containing reactant is dependent upon the specific reactants/reagents being used, but typically these allyl-containing species can be readily removed via flashing or distillation techniques, preferably flashing. For example, when allyl chloride and MCB are used, it is easy to remove the allyl chloride via a flash operation since the normal boiling point of allyl chloride is about 45⁰C while the normal boiling point of MCB is about 132⁰C. While a flash operation is desirable to remove the allyl-containing species, the removal may also be accomplished via distillation. Distillation offers the possibility of reducing the total volume of recycle involved but may result in higher initial capital outlays. To improve utilizations, the material that is flashed or distilled overhead can be recycled into the next alkylation reaction. If the material is recycled, care should be taken to minimize the amount of free phase water that is put back into the alkylation step; water from the quenching and washing steps forms an azeotrope with the allyl chloride/MCB mixture that goes overhead.

[0037] It should be noted that while the quenching and washing of the reaction mass is described herein as occurring before the removal of at least a portion of the allyl-containing species, these steps can be conducted in any order, but are preferably conducted as described. For example, the at least a portion of the allyl-containing species can be removed prior to the quenching of the reaction mass and optional further purification of the recovered organic phase. However, if done in this manner, experiments should be conducted to confirm that any residual water carried forward into the process, i.e. the bromination of the THPAI reaction mass, does not adversely affect THPAI product performance and/or yield. [0038] After quenching, optional washing, and removal of at least a portion of any allyl- containing species, further purification of the THPAI reaction mass may be done to separate the THPAI and any remaining solvent from process "heavies". Non-limiting examples of suitable techniques for achieving this are flashing, distillation, and the like while the method chosen is dependent upon the specific system. For example, if MCB and allyl chloride are used, MCB and THPAI may easily be separated from process heavies via a flash operation or distillation operation. It should be noted that it may be possible to separate the allyl choride, MCB, and THPAI from process heavies via flash or distillation prior to the quench and wash steps described above, and this is within the scope of the present invention, although not recommended. The concern with conducting the process in this order is that the bottoms removed will be so thick due to the solids present that processing at commercial scale will be difficult. These problems could be alleviated to some extent by adding a very low volatility "chaser solvent" to the reaction mass prior to flashing/distilling. Further, similar derivations of the particularly preferred embodiment, such as distilling or flashing off allyl chloride, MCB, and THPAI from process heavies followed by flashing or distilling off allyl chloride from the resultant mixture, may be contemplated, and are within the scope of the present invention, although not recommended for commercial scale operations. Bromination of THPAI Reaction Mass

[0039] Once the purified THPAI reaction mass has been obtained, it is brominated, either batch wise or continuously, usually with a slight excess, e.g. greater than about 2.0 molar equivalents bromine, to convert at least a portion, preferably substantially all, of the THPAI present in the THPAI reaction mass to tetraBr-THPAL It should be noted that even higher bromine levels of greater than about 2.16 bromine equivalents can be used. These higher bromine levels are preferred when MCB is used as a solvent because it is oftentimes difficult to induce crystallization of the tetraBr-THPAI in this embodiment even when the reaction mass is supersaturated with tetraBr-THPAI, and the addition of a larger excess of bromine increases the likelihood of crystallization.

[0040] It should be noted that the bromination reaction is exothermic, and it is desirable to meter in the bromine to match heat generation with heat removal capabilities. The bromine may be added in a number of ways including, but not limited to, as a neat liquid above the surface of the THPAI solution, as a neat liquid below the surface of the THPAI solution, as a solution in an unreactive solvent, such as chlorobenzene, either above or below the surface of the THPAI solution, as a neat vapor preferably below the surface of the THPAI solution, and as a component of a gaseous mixture preferably below the surface of the THPAI solution. For the latter, the components of the gaseous mixture should be selected such that they do not react with the bromine. One example of such a mixture would be bromine vapor in a nitrogen carrier gas. The addition of bromine is ideally done so that it is dispersed rapidly into the THPAI solution, for example atomized or as finely divided mist. This minimizes the potential to form locally high concentrations of bromine and/or hot spots, both of which may negatively impact product yields and purity/performance.

[0041] The temperature at which the bromination of the purified THPAI reaction mass is conducted is generally at one or more temperatures in the range of from about -4O⁰C to about 1 1O⁰C, preferably at one or more temperatures in the range of from about -5⁰C to about 1O⁰C. Brief excursions outside of this temperature range are possible and within the scope of the present invention, however, should there be a desire to operate outside of this range and especially on the higher side of these ranges, experiments should be conducted to determine the extent to which yields and final tetraBr-THPAI product purity/performance are affected. [0042] It should also be noted that it is preferred to add a free radical inhibitor such as, for example, butylated hydroxytoluene, to the purified THPAI reaction mass prior to bromination to suppress byproduct formation, which in turn will affect yields and may affect product purity and performance. Pyridine has been found to have some utility in this application. Workup of tetraBr-THPAI-Containing Product Mass

[0043] Following bromination of THPAI to tetraBr-THPAI, it is advantageous to remove at least a portion of any excess bromine from the reaction mass to reduce, preferably substantially eliminate, additional byproduct formation. Non-limiting examples of agents suitable for achieving the removal of at least a portion of excess bromine include reducing agents such as sodium sulfite, sodium formate, and hydrazine. Sodium sulfite reacts quickly with bromine and is relatively inexpensive so it is preferred in this invention. Due to ease of handling and increased reaction rate, it is further preferred to use an aqueous solution of sodium sulfite.

[0044] The removal of the at least a portion of excess bromine can be conducted at wide range of temperature, but it is typically conducted at one or more temperatures in the range of up to about 80⁰C. If MCB is used as a solvent, it is often desirable to add the sodium sulfite solution at a temperature in the range of from about 3O⁰C and about 40⁰C. [0045] It should be noted that in some circumstances the tetraBr-THPAI-containing product mass is typically a supersaturated solution of tetraBr-THPAI in MCB or as a thin slurry of tetraBr-THPAI in MCB even though solubility considerations alone dictate that more solids should be present. The addition of water (either neat or as a solution of sodium sulfite) can induce precipitation or additional precipitation depending upon the circumstances. If the sulfite solution is added below about 3O⁰C, the resultant slurry may be very thick which causes difficulty when stirring in commercial equipment; the increased solubility of tetraBr- THPAI above about 3O⁰C helps to keep the slurry reasonably thin. If it is desired to conduct the removal of the at least a portion of excess bromine at temperatures higher than about 8O⁰C, further experiments should be conducted to ensure that additional byproducts are not formed that deleteriously affect either yield or performance of the final tetraBr-THPAI product.

[0046] After at least a portion of any excess bromine has been removed, it is optional, but typically desirable and advantageous, to convert at least a portion, preferably substantially all, of any thermally unstable brominated by-product to a more stable species by the addition of a base. Non- limiting examples of suitable bases include sodium bicarbonate and potassium bicarbonate, preferably an aqueous solution of the base is used. In some embodiments the base is sodium carbonate, preferably aqueous sodium carbonate. The conversion of these brominated byproducts is desirable because some of these byproducts release hydrogen bromide at lower temperatures than tetraBr-THPAI. Since tetraBr-THPAI is typically processed with polymer at elevated temperatures, some of these impurities, if incorporated into the final tetraBr-THPAI product, may release HBr during that processing. The HBr may attack the polymer and reduce its molecular weight thereby adversely affecting the blended tetraBr-THPAI / polymer mix. If an aqueous base is used, it should be noted that phase separation can, and typically does occur, and the tetraBr-THPAI-containing organic phase can be recovered via ordinary phase separation techniques if so desired. In these embodiments, it is preferred to maintain the pH of the aqueous phase at one or more pH's in the range of from about 3 and to about 1 1 , preferably in the range of from about 7 and to about 10. It should be noted that at lower pH levels, the reactive brominated byproducts do not decompose as quickly as when higher pH's are used, but higher pH levels can cause the tetraBr-THPAI product to be attacked. The latter is especially a concern at elevated temperatures.

[0047] The removal of at least a portion of any brominated by-products is typically conducted at one or more temperatures chosen to consume the reactive byproducts but leave the tetraBr-THPAI largely unreacted. Generally, these temperatures are in the range of from about 1O⁰C to 12O⁰C and preferably at one or more temperatures in the range of from about 4O⁰C to 75⁰C.

[0048] It should be noted that up until this point of the process the tetraBr-THPAI product remains largely, and sometimes completely, in solution depending upon the solvent system chosen and the concentration of the tetraBr-THPAI in that solution. Thus, after at least a portion of any excess bromine and at least a portion of any brominated by-products have been removed, at least a portion, preferably substantially all, of the tetraBr-THPAI product can be isolated from the tetraBr-THPAI product-containing-reaction mass by i) crystallization, ii) precipitation, iii) solvent evaporation, or any combination of i)-iii).

[0049] In some embodiments, at least a portion of the tetraBr-THPAI product is recovered via crystallization and/or precipitation. In these embodiments, after at least a portion of any brominated by-products has been converted, one or more, typically one, antisolvent, i.e. a solvent that would facilitate the crystallization and/or precipitation of the tetraBr-THPAI product from solution, may be added to increase the yield of product. Non-limiting examples of antisolvents include aliphatic hydrocarbons such as petroleum ethers, cyclohexane, pentane, and heptane. Heptane or heptane-containing mixtures of hydrocarbons are preferred because 1) they are easy to separate from the MCB when solvent recycling is planned, 2) are not so volatile as to create special handling concerns, and 3) are and can increase the tetraBr- THPAI product yield by about 15% over a process that uses no antisolvent. It should be noted that if the solvent and antisolvent are to be recovered by distillation at the end of the process, it is advantageous if there is a large boiling point difference between the solvent and the antisolvent. Furthermore, the antisolvent chosen should not substantially react with the tetraBr-THPAI product.

[0050] The removal of at least a portion of excess bromine, optional conversion of at least a portion of any thermally unstable brominated by-products, and recovery of at least a portion of the tetraBr-THPAI product can be conducted either batch wise or continuously, independent of the bromination described above, i.e. if the bromination is conducted in a continuous manner, then these operations can still be conducted in a continuous or batchwise manner or vice versa. Further, each of these operations can itself be independently conducted in a batchwise or continuous manner from the others.

[0051] It should be noted that although the embodiment(s) described above depict the removal of at least a portion of any excess bromine followed by the removal of at least a portion of any brominated by-products, optionally followed by the addition of one or more antisolvent(s), the order of these can be changed depending upon the specific reagents being used if it benefits product quality, yield, and/or ease of operation. Furthermore, two or more of these steps may be combined into one if it is found to be advantageous. For example, if MCB is used as a solvent, aqueous sodium sulfite as the reducing agent, sodium carbonate as the base, and heptane as the antisolvent, it is advantageous to add a portion of the heptane after the sodium sulfite to aid in the precipitation of the product; the longer the product stays in a mix of chlorobenzene/heptane, the more likely it is to come out of solution as a powder. Although it would be advantageous, and within the scope of the present invention, to add the heptane even sooner, for example before at least portion of any excess bromine is removed or even before bromine is added to the THPAI solution, to realize these benefits, it is not advantageous because heptane may react with bromine, which would affect bromine utilizations and may affect product performance due to the introduction of new impurities. [0052] In some embodiments, the recovery of the at least a portion of the tetraBr-THPAI product is accompanied by the addition of tetraBr-THPAI product seed crystals to the tetraBr-THPAI product mass, if it benefits product quality, yield, and/or ease of operation. Ideally the seed crystals should be added at a point where the reaction mass is slightly saturated although adding them at other times may be contemplated.

[0053] After the tetraBr-THPAI product is precipitated and/or crystallized from the tetraBr- THPAI product mass, the tetraBr-THPAI product mass can be filtered to recover the tetraBr- THPAI product, which can be washed and dried. For washes in the MCB/heptanes solvent/antisolvent system, it is advantageous to wash with both water and heptanes. Water helps to reduce the levels of ionics (bromide, carbonate, bicarbonate, etc.) in the final product while heptanes help to increased final product purity by removing at least a portion of any remaining brominated byproducts.

[0054] In a particularly preferred embodiment, it is also advantageous to add water to the tetraBr-THPAI product containing reaction mass prior to filtration to further aid in reducing the level of ionics in the final tetraBr-THPAI product. This water may be added at any one of several different spots in the process including before addition of sodium sulfite, after addition of sodium sulfite, after addition of sodium carbonate, after addition of heptane antisolvent, etc.

[0055] Once filtered and washed, the tetraBr-THPAI product may be dried using one of several standard drying systems that exist commercially. Attention should be paid to the temperature at which the material is being dried especially when it is wet with water. If the temperature is too high, the water has the potential to react with the tetraBr-THPAI product or with impurities in the tetraBr-THPAI product to generate HBr. Such decomposition has the potential to adversely impact product performance. Generally the drying is conducted at one or more temperatures in the range of from about 1O⁰C to about 7O⁰C, preferably at one or more temperatures in the range of from about 30⁰C to about 50⁰C. Other Methods of Isolating tetraBr-THPAI Product

[0056] Although it is preferred that the tetraBr-THPAI product be recovered via crystallization/precipitation, additional methods of isolation may be contemplated including, but not limited to, solvent evaporation. The tetraBr-THPAI product may be recovered via solvent evaporation, through the stripping of the solvent overhead or more preferably through a devolitization extruder where overall retention times will be minimized. The latter is important because the removal process will likely need to be carried out at temperatures where tetraBr-THPAI may decompose; short retention times will minimize any decomposition.

[0057] It should be noted that the recovery of the tetraBr-THPAI product via solvent evaporation provides for higher overall yields on a mass basis, the purities of the tetraBr- THPAI product will generally be lower when compared to tetraBr-THPAI products recovered via crystallization/precipitation.

[0058] If the tetraBr-THPAI product is recovered from the tetraBr-THPAI product containing reaction mass via solvent evaporation, it is still desirable to practice the conversion of brominated byproducts mentioned above to improve the performance of the final product. In this embodiment, following conversion of the brominated byproducts, it is advantageous to phase separate any aqueous layer away from the organic layer to limit the incorporation of ionics into the final tetraBr-THPAI product. Furthermore if MCB is used as the solvent, it is advantageous to add a hydrocarbon such as heptane to the MCB-containing organic phase. Depending upon conditions, two organic phases may develop, one rich in hydrocarbon and brominated byproducts and one rich in MCB and tetraBr-THPAI. Phase separating away the hydrocarbon/byproducts-rich phase prior to evaporation of solvent helps to purify the final tetraBr-THPAI product. An additional benefit of this separation is that the form that the final product takes is oftentimes more of a solid than a highly viscous liquid; the byproducts that are removed in the heptane-rich phase seem to hinder the product from fully solidifying. [0059] The above description is directed to several embodiments of the present invention. Those skilled in the art will recognize that other means, which are equally effective, could be devised for carrying out the spirit of this invention. It should also be noted that preferred embodiments of the present invention contemplate that all ranges discussed herein include ranges from any lower amount to any higher amount.

[0060] The following example will illustrate the present invention, but are not meant to be limiting in any manner.

EXAMPLE Alleviation

[0061] Into a 1 liter Hastelloy C2000 autoclave equipped with dual pitched blade impellers, a thermowell, and a back pressure regulator set near 70 psig was charged:

1. 21Og of THPI (96%), 24g of fresh MCB,

2. 273g of recycled MCB containing 2.60 wt.% allyl chloride and 0.18 wt.% butyl chloride,

3. 14 Ig of recycled MCB containing 0.1 wt.% hydrocarbons as heptane,

4. 125g of fresh allyl chloride,

5. 184g ofNa2CO3, and

6. 5.6g TBAB

[0062] The mixture was heated to 130⁰C and maintained there for 6 hours. At the end of that time the autoclave was cooled in an ice water bath and sampled for conversion (normalized GC area % of 0.43 starting THPI, 95.84 THPAI, and 3.73 di-allyl species). The reaction mass was then quenched into water and washed with water to afford a solution of THPAI in MCB. Note that about 1 lOOg of water is required to completely dissolve the reaction salts at 5O⁰C.

[0063] 5 additional runs were conducted using similar charges and procedures to the one given above. The total mass of THPI charged in these six experiments was 1264g. Afterwards, all 6 solutions of THPAI in MCB were combined to yield 4172g solution. The assay on this material as determined by quantitative H-NMR was 34.7 wt.% which is equal to a 94.3% molar yield from THPI if the THPI had a purity of 96%.

[0064]41 11g of the solution were carried forward and flashed (in multiple experiments) at about -12.9 psig with an ending bottoms temperature of about 84⁰C to remove unreacted allyl chloride. 1266 grams of distillate was obtained along with 2836 grams of bottoms material. The bottoms material was found to contain 49.0 wt.% THPAI which corresponds to a 97.4% accountability during the flash. The material was used as is in a bromination as described below.

Bromination of THPAI reaction mass

[0065] 1. To a 12 L jacketed glass flask was charged 3,056 g of a crude THPAI in monochlorobenzene solution containing 27.5 GC wt% of THPAI. 7.0 g of pyridine was then added to the jacketed flask.

[0066] 2. Under a N₂ pad, the reactor contents were cooled to 2.8⁰C. After the reactor contents were cooled, 1,540 g of Br₂ was continuously fed while to the reactor over 5.7 hours while maintaining the reactor contents within the temperature range of from about 0.9 to 4.6⁰C.

[0067] 3. After the feeding of the Br₂ in 2. was complete, the resulting reaction mass was stirred for about 0.8 hours while maintaining the temperature of the reaction mass within the range of from about 0⁰C to about 5°C, and then an additional 27 g of Br₂ was fed continuously over a ten minute period to the reactor while maintaining the temperature of the reaction mass within the range of from about 2.9-5.1⁰C.

[0068] 4. The reaction mixture resulting from 3. was then heated to about 3O⁰C in 30 min. and held at about 32⁰C for about 30 min., resulting in an yellow-orange slurry. [0069] 5. 160 g of water and then 28Og of 10 wt% aqueous sodium sulfite were fed continuously to the reactor over a 42 minute period while maintaining the temperature of the reactor contents at about 3O⁰C, and then 700 g of an aqueous 5 wt% sodium carbonate solution was fed continuously over a 26 minute period.

[0070] 6. After 5., 1,140 g of heptane anti-solvent was fed continuously over a 32 minute period, and the reactor contents were heated to 43⁰C during the feeding. [0071] 7. 700 g of 5 wt% aqueous sodium carbonate was then fed continuously over a 35 minute period while the reactor contents were heated to 49⁰C in 15 min. and then to 51.3⁰C when the sodium carbonate feed was complete.

[0072] 8. The mixture resulting from 8. was then stirred for additional 1 hour and 10 min while maintaining the temperature of the reactor contents at about 52⁰C.

[0073] 9. The reactor contents were then cooled to 47.8⁰C in 10 minutes, and 2,0 g of

THPAI seed crystals were added. The reactor contents were then cooled to 40.1⁰C in 25 minutes, resulting in a thin slurry.

[0074] 10. After 9., the contents of the reactor were held at about 4O⁰C for 1 hour for crystallization/precipitation. After the one hour had elapsed, 1,000 g of heptane anti-solvent were continuously fed to the resultant thin slurry over a 0.7 hour period while maintaining the temperature of the reactor contents at about 4O⁰C.

[0075] 11. After 10., the reactor contents were cooled to 26⁰C in 1.2 hours. About 1.6 liters of the cooled reactor contents were removed from the reactor.

[0076] 12. After 11., about half of the remaining reactor contents were filtered on a 3 L coarse frit. The resulting wet cake was washed with 2,000 cc of water, and the washed wet cake (about 1230 grams) was dried in a vacuum oven at about 50⁰C to obtain a dry tetrabrom-

THPAI product (935 g), which had 0.2 ppm Fe & 83 ppm Na, as determined by ICP; 338 ppm bromide, 12 ppm chloride, and 145 ppm HBr as determined by QC; 98.0 wt% tetraBr-

THPAI purity by NMR and 96.4 wt% purity by LC.

[0077] 13. The remaining slurry was then filtered on the same frit, the resulting wet cake washed with 2,000 cc of water and then 750 g of heptane, and then the wet cake (1,173 g) was dried in the vacuum oven to obtain a dry tetrabrom-THPAI product (852.8 g), containing

0.9 ppm Fe and 60 ppm Na by ICP; 272 ppm bromide, 11 ppm chloride, and 129 ppm HBr by

QC; 97.6 wt% purity by NMR and 97.3 wt% purity by LC.

Claims

WHAT IS CLAIMED

1) A process comprising:

A) heating a mixture containing cis-l,2,3,6-tetrahydrophthalimide ("THPI"), a base, an allyl-containing species, an organic solvent, and optionally a phase transfer catalyst, to one or more temperatures in the range of from about 3O⁰C to about 300⁰C thereby forming a reaction mass containing N-allyl-cis-l,2,3,6-tetrahydrophthalimide ("THPAI");

B) purifying the reaction mass thereby producing a purified THPAI reaction mass;

C) brominating the purified THPAI reaction mass at one or more temperatures in the range of from about -4O⁰C to about HO⁰C thereby forming a first product reaction mass containing tetraBr-THPAI and one or more brominated byproducts; and,

D) removing at least a portion of any residual free bromine from the first product reaction mass thereby forming a second product reaction mass;

E) optionally, treating the second product reaction mass to selectively convert at least a portion of any reactive brominated byproducts into less reactive species thereby forming a third product reaction mass;

F) isolating at least a portion of the tetraBr-THPAI product in the third product reaction mass through i) crystallization, ii) precipitation, iii) solvent evaporation, or any combination of i)-iii); and optionally

G) washing and drying the isolated tetraBr-THPAI product if it was isolated through crystallization or precipitation.

2) The process according to claim 1 wherein said base is a metal carbonate; said allyl- containing species is an allyl halide; said phase transfer catalyst is selected from quaternary alkyl and/or aryl ammonium phase transfer catalysts, crown ethers, substituted amines, and combinations thereof.

3) The process according to claim 1 wherein said process includes E).

4) The process according to claim 1 wherein said process includes G).

5) The process according to any of claims 2 or 4 wherein the tetraBr-THPAI product in the third product reaction mass is isolated through i) crystallization, and/or ii) precipitation.

6) The process according to claim 1 wherein said at least a portion of any residual free bromine is removed from the first product reaction mass by contacting the first product reaction mass with aqueous sodium sulfite, sodium bisulfite, or sulfurous acid.

7) The process according to claim 1 wherein B) comprises: i) removing at least a portion of any inorganic and organic salts from the reaction mass by dissolving the salts into water and then phase separating the THPAI- containing organic phase from the water-containing aqueous phase; and ii) washing the resultant THPAI-containing organic phase one or more times with water, wherein after each washing, the organic phase is separated from the aqueous phase, thereby forming the purified THPAI reaction mass.

8) The process according to claim 7 wherein at least a portion of any excess allyl-containing species is removed from the purified THPAI reaction mass prior to C).

9) The process according to claim 8 wherein at least a portion of any reaction by-products having a boiling point higher than the THPAI are removed from the purified THPAI reaction mass prior to C).

10) The process according to claim 1 wherein when conducting A), only a portion of the allyl-containing species is fed with the other reactants prior to heating, and, once the reactor contents reach the desired temperature the remaining portion of the allyl- containing species is fed over time, optionally at a constant rate.

1 l)The process according to any of claims 1-4 or 5-10 wherein the allyl-containing species is allyl chloride; said base is potassium carbonate or sodium carbonate; and the organic solvent is selected from chlorobenzene, bromobenzene, benzene, ethers, and esters.

12) The process according to any of claims 1 or 7-9 wherein when conducting B), the at least a portion of the excess allyl-containing species removed is removed by flashing or distillation, with or without a portion of the organic solvent.

13) The process according to claim 9 wherein when conducting B), the at least a portion of any reaction by-products having a boiling point higher than the THPAI are removed from the purified THPAI reaction mass by distilling or flashing at least a portion of the organic solvent and THPAI overhead, optionally after quenching and washing the reaction mass with water and removal of at least a portion of any excess allyl-containing species from the purified THPAI reaction mass.

14) The process according to claim 1 wherein C), D), E), F)₅ and G), if present, are conducted in a continuous manner.

15) The process according to claim 1 wherein C), D), E), F), and G), if present, are conducted in a batch-wise manner.

16) The process according to claim 1 wherein a) the amount of base used is in the range of from about 0.45 to about 8.00 equivalents per equivalent of THPI, in the range of from about 1.05 to 2.00 equivalents of THPI, or in the range of from about 1.15 to 1.25 equivalents of THPI; b) the amount of allyl-containing species used is in the range of from about 0.80 equivalents to about 6.00 equivalents of allyl-containing species per equivalent of THPI, in the range of from about 1.02 to about 1.50 equivalents of allyl- containing species per equivalent of THPI, or in the range of from about 1.10 to about 1.25 equivalents of allyl-containing species per equivalent of THPL; c) the amount of organic solvent used is in the range of from about 0.1 to about 20 volumes of organic solvent per volume of THPI, in the range of from about 1.0 to about 10.0 volumes of organic solvent per volume of THPI, or in the range of from about 1.5 to about 2.5 volumes of organic solvent per volume of THPI; and d) the amount of phase transfer catalyst, if used, is in the range of from about 0.001 equivalents to about 1.00 equivalents of phase transfer catalyst per equivalent of THPI, in the range of from about 0.005 to about 0.020 of phase transfer catalyst per equivalent of THPI, or in the range of from about 0.008 to about 0.016 of phase transfer catalyst per equivalent of THPI.

17) The process according to claim 16 wherein the temperature in A) is maintained at one or more temperatures in the range of from about 75⁰C to about 200⁰C, or at one or more temperatures in the range of from about 11O⁰C to about 15O⁰C.

18) The process according to claim 1 wherein the amount of bromine used in C) is 2 or more equivalents of bromine per equivalent of THPAI.

19) The process according to claim 3 wherein the removal of at least a portion of any brominated by-products is accomplished by the addition of a base or an aqueous base, and then recovering the tetraBr-THPAI product containing organic phase.

20) The process according to claim 19 wherein the pH of the aqueous phase is maintained at one or more pH's in the range of from about 3 and to about 11.

21) The process according to claim 19 wherein the removal of at least a portion of any brominated by-products is conducted at one or more temperatures in the range of from about 10°C to 12O⁰C.

22) The process according to claim 1 wherein a free radical inhibitor is added to the THPAI reaction mass prior to C)

23) The process according to claim 22 wherein said free radical inhibitor is butylated hydroxytoluene.

24) A process comprising:

A) heating in a reactor a mixture containing THPI, sodium carbonate, allyl chloride, an organic solvent, and tetrabutylammonium bromide ("TBAB") phase transfer catalyst to one or more temperatures in the range of from about 60⁰C to 25O⁰C wherein the pressure of the reactor is maintained at one or more pressures up to the pressure rating of the reactor thereby forming a reaction mass containing at least THPAI and one or more impurities;

B) purifying the reaction mass thereby producing a purified THPAI reaction mass;

C) brominating the purified THPAI reaction mass at one or more temperatures in the range of from about -4O⁰C to about HO⁰C thereby forming a first product reaction mass containing tetraBr-THPAI and one or more brominated byproducts;

D) removing at least a portion of any residual free bromine from the first product reaction mass, thereby forming a second product reaction mass;

E) treating the second product reaction mass with aqueous sodium carbonate at one or more temperatures in the range of from about 1O⁰C to 12O⁰C to convert at least a portion of any reactive brominated byproducts into less reactive species thereby forming a third product reaction mass;

F) isolating at least a portion of the tetraBr-THPAI product in the third reaction mass through i) crystallization, ii) precipitation, iii) solvent evaporation, iv) the use a devolatization extruder, or any combination of i)-iv); and optionally,

G) washing and drying the isolated tetraBr-THPAI product if it was isolated through crystallization or precipitation.

25) The process according to claim 24 wherein the organic solvent is monochlorobenzene ("MCB").

26) The process according to claim 25 wherein said at least a portion of any residual free bromine is removed from the first product reaction mass by contacting the first product reaction mass with aqueous sodium sulfite, sodium bisulfite, or sulfurous acid, thereby producing a second product reaction mass comprising residual bromine, aqueous sodium sulfite, sodium bulfite, and/or sulfurous acid.

27) The process according to claim 24 wherein said process includes G).

28) The process according to claim 24 wherein when conducting A), only a portion of the allyl-chloride is fed with the other reactants prior to heating, and, once the reactor contents reach the desired temperature the remaining portion of the allyl chloride is fed over time, optionally at a constant rate.

29) The process according to claim 24 wherein C), D), E), F), and G), if present, are conducted in a continuous manner. 30) The process according to claim 24 wherein C), D), E), F), and G), if present, are conducted in a batch-wise manner.

31) The process according to claim 24 wherein said B) comprises: i) removing at least a portion of any inorganic and organic salts from the reaction mass by dissolving the salts into water and then phase separating the THPAl- containing organic phase from the water-containing aqueous phase; and ii) washing the resultant THPAI-containing organic phase one or more times with water, wherein after each washing, the organic phase is separated from the aqueous phase, thereby forming the purified THPAI reaction mass.

32) The process according to claim 31 wherein at least a portion of any excess allyl-chloride is removed from the purified THPAI reaction mass prior to C).

33) The process according to claim 32 wherein at least a portion of any reaction by-products having a boiling point higher than the THPAI are removed from the purified THPAI reaction mass prior to C).

34) The process according to claims 31 wherein when conducting B), the at least a portion of the excess allyl-chloride removed is removed by flashing or distillation, with or without a portion of the organic solvent.

35) The process according to claim 31 wherein when conducting B), the at least a portion of any reaction by-products having a boiling point higher than the THPAI are removed from the purified THPAI reaction mass by distilling or flashing at least a portion of the organic solvent and THPAI overhead, optionally after quenching and washing the reaction mass with water and removal of at least a portion of any excess allyl chloride from the purified THPAI reaction mass.

36) The process according to claim 31 wherein when conducting B), the at least a portion of any reaction by-products having a boiling point higher than the THPAI are removed from the purified THPAI reaction mass by distilling or flashing substantially all of the organic solvent, THPAI, and any remaining allyl-containing species overhead, wherein said overhead is said purified THPAI reaction mass, and optionally recovering at least a portion of the allyl-chloride from the overhead.

37) The process according to claim 25 wherein a) the amount of base used is in the range of from about 0.45 to about 8.00 equivalents per equivalent of THPI, in the range of from about 1.05 to 2.00 equivalents of THPI, or in the range of from about 1.15 to 1.25 equivalents of THPI; b) the amount of allyl-containing species used is in the range of from about 0.80 equivalents to about 6.00 equivalents of allyl-containing species per equivalent of THPI, in the range of from about 1.02 to about 1.50 equivalents of allyl- containing species per equivalent of THPI, or in the range of from about 1.10 to about 1.25 equivalents of allyl-containing species per equivalent of THPL; c) the amount of organic solvent used is in the range of from about 0.1 to about 20 volumes of organic solvent per volume of THPI, in the range of from about 1.0 to about 10.0 volumes of organic solvent per volume of THPI, or in the range of from about 1.5 to about 2.5 volumes of organic solvent per volume of THPI; and d) the amount of phase transfer catalyst used is in the range of from about 0.001 equivalents to about 1.00 equivalents of phase transfer catalyst per equivalent of THPI, in the range of from about 0.005 to about 0.020 of phase transfer catalyst per equivalent of THPI, or in the range of from about 0.008 to about 0.016 of phase transfer catalyst per equivalent of THPI.

38) The process according to claim 37 wherein the temperature in A) is maintained at one or more temperatures in the range of from about 75⁰C to about 200⁰C, or at one or more temperatures in the range of from about HO⁰C to about 15O⁰C.

39) The process according to claim 37 wherein the amount of bromine used in C) is 2 or more equivalents of bromine per equivalent of THPAI.

40) The process according to claim 37 wherein the removal of at least a portion of any brominated by-products is accomplished by the addition of a base or an aqueous base, and then recovering the tetraBr-THPAI product containing organic phase.

41) The process according to claim 40 wherein the pH of the aqueous phase is maintained at one or more pH's in the range of from about 3 and to about 11.

42) The process according to claim 37 wherein the removal of at least a portion of any brominated by-products is conducted at one or more temperatures in the range of from about 1O⁰C to 12O⁰C.

43) The process according to claim 34 wherein a free radical inhibitor is added to the THPAI reaction mass prior to C)

44) The process according to claim 43 wherein said free radical inhibitor is butylated hydroxytoluene.

45) A process for forming a tetraBr-THPAI product from THPI, sodium carbonate, MCB, TBAB, and allyl chloride comprising:

A) introducing into a reactor THPI₅ sodium carbonate, MCB, TBAB, and a portion of the allyl chloride;

B) heating the reactor contents to one or more temperatures in the range of from about 8O⁰C to about 25O⁰C; C) introducing into the reactor the remainder of the allyl chloride thereby forming a reaction mass

D) cooling the reaction mass to a temperature in the range of from about -10⁰C to about 100⁰C thereby forming a cooled reaction mass;

E) removing at least a portion of any inorganic and organic salts from the cooled reaction mass by a) quenching the cooled reaction mass with water, b) recovering the organic phase from a) via phase separation; and optionally repeating one or more times the following; c) washing the organic phase recovered in b) with water and recovering the organic phase from c) via phase separation techniques;

F) removing at least a portion of any excess allyl chloride in the recovered organic phase from E) via flashing or distillation thereby producing a THPAI reaction mass;

G) brominating the THPAI reaction mass at one or more temperatures in the range of from about -40⁰C to about 110⁰C thereby forming a first product reaction mass containing tetraBr-THPAI and one or more brominated byproducts;

H) removing at least a portion of any residual free bromine from the first product reaction mass by contacting the first product reaction mass with aqueous sodium sulfite thereby forming a second product reaction mass containing residual bromine and aqueous sodium sulfite, sodium bisulfite, and/or sulfurous acid;

I) treating the second product reaction mass with aqueous sodium carbonate at one or more temperatures in the range of from about 3O⁰C to 100⁰C while maintaining the pH of the second product reaction mass at pH in the range of from about 4 to about 10.5 thereby forming a third product reaction mass

K) isolating at least a portion, preferably substantially all, of the tetraBr-THPAI product in the third reaction mass via precipitation using one or more aliphatic hydrocarbons;

L) recovering at least a portion of the tetraBr-THPAI product; and

M) washing and drying the isolated tetraBr-THPAI product.

46) The process according to claim 45 wherein G), H), I), J), K), L), and M are conducted in a continuous manner.

47) The process according to claim 45 wherein G)_? H), I), J), K), L), and M are conducted in a batch-wise manner.

48) The process according to claim 45 wherein a free radical inhibitor is added to the THPAI reaction mass prior to G)

49) The process according to claim 48 wherein said free radical inhibitor is butylated hydroxytoluene.