Quaternary ammonium hydroxide polymers

Manufacture. For the commercial production of DPXN (di-/)-xylylene) (3), two principal synthetic routes have been used the direct pyrolysis of -xylene (4, X = Y = H) and the 1,6-Hofmaim elimination of ammonium (HNR3 ) from a quaternary ammonium hydroxide (4, X = H, Y = NR3 ). Most of the routes to DPX share a common strategy PX is generated at a controlled rate in a dilute medium, so that its conversion to dimer is favored over the conversion to polymer. The polymer by-product is of no value because it can neither be recycled nor processed into a commercially useful form. Its formation is minimised by careful attention to process engineering. The chemistry of the direct pyrolysis route is shown in equation 1 ... 

Deliberate production of (vinyl)polystyrene from (toluenesul-foxyethyl)polystyrene or (haloethyl)polystyrenes was best accomplished by quaternization with N,N-dimethylaminoethanol, followed by treatment with base beta-deprotonation is encouraged in the cyclic zwitterionic intermediate. Reaction was faster and cleaner than with other reagents recommended (64, 76, 77) for eliminations, such as alkoxide, diazabicycloundecene or quaternary ammonium hydroxide this new and efficient procedure may find application elsewhere. Hydrometallation or other additions to polymer-bound olefin may prove useful steps in future syntheses by polymer modification. 

J.M. Challinor, On the mechanism of high temperature reactions of quaternary ammonium hydroxides with polymers, J. Anal. Appl. Pyrol., 29, 223 224 (1994). 

Because of their high lipophobic character, compared with other ammonium salts, quaternary ammonium hydroxides are not readily prepared by liquidrliquid anion exchange. Only with quaternary ammonium hydrogen sulphates is it possible to transfer the ammonium hydroxide into the organic phase in any viable degree of concentration [30] and this procedure remains the cheapest and simplest procedure. Other methods include treatment of quaternary ammonium halides with silver oxide [31] and by anion exchange using polymer bound hydroxide [e.g. 32]. 

A quaternary ammonium hydroxide ion exchange resin 6 was shown to sequester phenols, hydroxypyrazoles, and other weakly acidic heterocycles.25 The sequestered nucleophiles could also be used as polymer-supported reactants. Similarly, the guanidine-functionalized resin 7 was also shown to be a useful capture agent for weakly acidic nucleophiles, including phenols and cyclic iV-acyl sulfonamides.26... 

The increase in alkylation efficiency of HEC with quaternary ammonium hydroxide is not limited to DPGE. Experiments were conducted in which HEC was alkylated with 1-bromohexadecane (cetyl bromide), 3-n-pentadecenyl phenyl glycidyl ether (PDPGE)14, or 1,2-epoxyhexadecane (C]6 a-olefin epoxide) in the presence of either sodium hydroxide or benzyltrimethylammonium hydroxide. As before, the molar A/HEC ratio was 0.50, and the water content of the diluent in the benzyltrimethylammonium hydroxide experiment was decreased to compensate for the higher water content of the base so that the final water content of both reactions was the same (14.4%). The hexadecyl content of the polymers was measured by gas chromatography. The sodium hydroxide mediated reaction of 1-bromohexadecane yielded a hexadecyl alkylation efficiency of 0.5%, while the benzyltrimethylammonium hydroxide reaction yielded a hexadecyl alkylation efficiency of 6.2%. A twelve-fold increase in the hexadecyl alkylation efficiency was observed in the reaction conducted with the quaternary ammonium hydroxide. 

Polymer-supported quaternary ammonium hydroxides have been used to catalyse Michael reactions between various alkyl methacrylates, acrylonitrile, and methyl vinyl ketone as acceptors and nitro or keto derivatives as donors.[116,117]... 

The mechanism of formation of methyl esters from polyesters can be simpler, not involving the formation of an intermediate compound. Pyrolysis of ester type polymers in the presence of quaternary ammonium hydroxides such as TMAH may occur by the following simple steps a) the polymer when mixed with TMAH and heated to temperatures around 400° C undergoes hydrolysis because of the strong basic character of the reagent, b) TMAH salts of the hydrolyzed products are formed, c) the salts undergo thermal fragmentation to the methyl derivatives [40]. 

J. Urbanski (51) developed a nucleophilic colour reaction of dinitroarene-lulphonic esters with primary and secondary amines and quaternary ammonium hydroxides. The reaction was originally tised to determine small quantities of epoxy groups in polymers. The coloured products possess the structure of a-complexes, for example V ... 

Gao, H., J. Li, and K. Lian. 2014. Alkaline quaternary ammonium hydroxides and their polymer electrolytes for electrochemical capacitors. RSC Advances 4 21332-21339. 

The fundamental theory of phase transfer catalysis (PTC) has been reviewed extensively. Rather than attempt to find a mutual solvent for all of the reactive species, an appropriate catalyst is identified which modifies the solubility characteristics of one of the reactive species relative to the phase in which it is poorly solubilized. The literature on the use of PTC in the preparation of nitriles, halides, ether, and dihalocarbenes is extensive. Although PTC in the synthesis of C- and 0-alkylated organic compounds has been studied, the use of PTC in polymer synthesis or polymer modification is not as well studied. A general review of PTC in polymer synthesis was published by Mathias. FrecheE described the use of PTC in the modification of halogenated polymers such as poly(vinyl bromide), and Nishikubo and co-workers disclosed the reaction of poly(chloromethylstyrene) with nucleophiles under PTC conditions. Liotta and co-workers reported the 0-alkylation of bituminous coal with either 1-bromoheptane or 1-bromooctadecane. Poor 0-alkylation efficiencies were reported with alkali metal hydroxides but excellent reactivity and efficiencies were found with the use of quaternary ammonium hydroxides, especially tetrabutyl- and tetrahexylammonium hydroxides. These results are indeed noteworthy because coal is a mineral and is not thought of as a reactive and swellable polymer. Clearly if coal can be efficiently 0-alkylated under PTC conditions, then efficient 0-alkylation of cellulose ethers should also be possible. 

Alkaline-based polymer electrolyte membranes are relative newcomers on the scene. It has been widely believed that the quaternary ammonium hydroxide functional group (RN4 , OH ), which is the one used in most anion exchange membranes, is self-destructive, because the OH- ion is likely to attack the RN4 cation. In addition, the specific conductivity of an OH conducting ionomer was suspected of being at least a factor 3-A lower than that of the H" conducting... 

The second type of CO2 fiber-optic chemical sensor is constructed by using ion pairs consisting of a pH indicator anion and an organic quaternary cation. First, a pH indicator dye (DH) and a quaternary ammonium hydroxide (Q OH ) are entrapped into a proton-impermeable but CO2-permeable polymer membrane, which is then immobilized onto the fiber s surface. The mechanism of this CO2 sensor is based on the interaction between the dye molecules (DH) and the quaternary cations (Q+OH ) to form hydrated ion pairs (Q D XH2O). The hydrated ion pair is dissolved in the polymer, where it reacts with CO2 according to the following reaction ... 

In contrast, liquidiliquid phase-transfer catalysis is virtually ineffective for the conversion of a-bromoacetamides into aziridones (a-lactams). Maximum yields of only 17-23% have been reported [31, 32], using tetra-n-butylammonium hydrogen sulphate or benzyltriethylammonium bromide over a reaction time of 4-6 days. It is significant that a solidiliquid two-phase system, using solid potassium hydroxide in the presence of 18-crown-6 produces the aziridones in 50-94% yield [33], but there are no reports of the corresponding quaternary ammonium ion catalysed reaction. Under the liquidiliquid two-phase conditions, the major product of the reaction is the piperazine-2,5-dione, resulting from dimerization of the bromoacetamide [34, 38]. However, only moderate yields are isolated and a polymer-supported catalyst appears to provide the best results [34, 38], Significant side reactions result from nucleophilic displacement by the aqueous base to produce hydroxyamides and ethers. 

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