Polymerization phenothiazine

GOM 02] Gomurasvili Z., Crivello J.V., Monomeric and polymeric phenothiazine photosensitizers for photoinitiated cationic polymerization . 

The Hofmann elimination route, of which many versions exist, can be carried out at much lower temperatures in conventional equipment. The PX is generated by a 1,6-Hofmaim elimination of amine from a quaternary ammonium hydroxide in the presence of a base. This route gives yields of 17—19%. Undesired polymeric products can be as high as 80% of the product. In the presence of a polymerization inhibitor, such as phenothiazine, DPXN yields can be increased to 50%. 

Continuous polymerization in a staged series of reactors is a variation of this process (82). In one example, a mixture of chloroprene, 2,3-dichloro-l,3-butadiene, dodecyl mercaptan, and phenothiazine (15 ppm) is fed to the first of a cascade of 7 reactors together with a water solution containing disproportionated potassium abietate, potassium hydroxide, and formamidine sulfinic acid catalyst. Residence time in each reactor is 25 min at 45°C for a total conversion of 66%. Potassium ion is used in place of sodium to minimize coagulum formation. In other examples, it was judged best to feed catalyst to each reactor in the cascade (83). 

Oxidation of P-nicotinamide adenine dinucleotide (NADH) to NAD+ has attracted much interest from the viewpoint of its role in biosensors reactions. It has been reported that several quinone derivatives and polymerized redox dyes, such as phenoxazine and phenothiazine derivatives, possess catalytic activities for the oxidation of NADH and have been used for dehydrogenase biosensors development [1, 2]. Flavins (contain in chemical structure isoalloxazine ring) are the prosthetic groups responsible for NAD+/NADH conversion in the active sites of some dehydrogenase enzymes. Upon the electropolymerization of flavin derivatives, the effective catalysts of NAD+/NADH regeneration, which mimic the NADH-dehydrogenase activity, would be synthesized [3]. 

Polymerizations using trialkylborons are not slowed as mueh as is normal by the presenee of eonventional inhibitors sueh as p-phenylenediamine, hydro-quinone, benzoquinone, phenothiazine or others [74]. This has been attributed to... 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials No reaction Stability During Transport Normally unstable but will be detonate Neutralizing Agents for Acids and Caustics Wash with water, rinse with sodium bicarbonate solution Polymerization May occur in contact with acids, iron salts, or at elevated temperatures and release high energy rapidly may cause explosion under confinement Inhibitor of Polymerization Monomethyl ether of hydroquinone 180-200 ppm phenothiazine (for tech, grades) 1000 ppm hydroquinone (0.1 %) methylene blue (0.5... 

Substituted anilines behave similarly to the phenols, although relatively little data are available. A-phenyl-iV -isopropyl-p-phenylenediamine is an efficient inhibitor in the polymerization of styrene only in the presence of oxygen [Winkler and Nauman, 1988], However, the effectiveness of phenothiazine as an inhibitor in the polymerization of acrylic acid is independent of oxygen [Levy, 1985],... 

Chloroprene is available commercially on a restricted basis in the United States as crude P-chloroprene with a minimum purity of 95% (Lewis, 1993 DuPont Dow Elastomers, 1997). The principal impurities are dichlorobutene and solvents, with smaller amounts of 1-chlorobutadiene (a-chloroprene), chlorobutenes and dimers of both chloroprene and butadiene. Due to its reactivity, chloroprene is stored at 0°C or below under nitrogen and contains significant quantities of inhibitors, such as phenothiazine, tert-butylcatechol, picric acid and the ammonium salt of A -nitroso-N-phenylhydroxy lamine, to prevent degradation and polymerization (Stewart, 1993). Generally within six weeks of manufacture, crude chloroprene is distilled to produce polymerization grade, which is used within approximately 24 h of distillation. 

Carbazole, like most aromatic amines, oxidizes readily via electron transfer. We recognized early that electron transfer may be an important initiation process for polymerizing the N-vinyl derivative. Some years ago we showed (29) that cycloheptatrienyl cation could act as an efficient one-electron transfer reagent, producing the appropriate cation radicals from reactive amines such as phenothiazine and tetramethyl-p-phenylene-diamine. It was also suggested that the product of the reaction between cycloheptatrientyl cation and carbazole itself was the carbazole cation radical. However, our recent work (21) has demonstrated that one-electron oxidation of carbazole leads directly to the 3,3-dicarbazoyl cation radical (VII). 

Various compounds were shown to sensitize the photochemical decomposition of pyridinium salts. Photolysis of pyridinium salts in the presence of sensitizers such as anthracene, perylene and phenothiazine proceeds by an electron transfer from the excited state sensitizer to the pyridinium salt. Thus, a sensitizer radical cation and pyridinyl radical are formed as shown for the case of anthracene in Scheme 15. The latter rapidly decomposes to give pyridine and an ethoxy radical. Evidence for the proposed mechanism was obtained by observation of the absorption spectra of relevant radical cations upon laser flash photolysis of methylene chloride solutions containing sensitizers and pyridinium salt [64]. Moreover, estimates of the free energy change by the Rehm-Weller equation [65] give highly favorable values for anthracene, perylene, phenothiazine and thioxanthone sensitized systems, whilst benzophenone and acetophenone seemed not to be suitable sensitizers (Table 5). The failure of the polymerization experiments sensitized by benzophenone and acetophenone in the absence of a hydrogen donor is consistent with the proposed electron transfer mechanism. 

Cationic polymerization of thiiranes CMT (9-(thiiran-2-ylmethyl)-9//-carbazole) 217 and PMT (10-(thiiran-2ylmethyl)-1077-phenothiazine) 218 was studied by a Lithuanian group <2002JPH63>. Initiators were di-(/-butylphenyl)iodonium tetrafluoroborate (BPIT), diphenyliodonium tetrafluoroborate, cyclopropyldiphenylsulfonium tetrafluoroborate, and ( 7 -2,4-cyclopentadien-1 -yl) [1,2,3,4,5,6- )-( 1 -methylethyl)benzene]-iron(- -)-hexafluorophosphate(—1). The influences of temperature and initiator concentration on the polymerization rate and the conversion limit were determined. The values of initiator exponent and activation energy for the photopolymerization of CMT and PMT initiated with BPIT in 1,2-dichloroethane was established. 

A polyadduct formed from aniline, phenothiazine, oxirane and 2,3-epoxypropane [145] was proposed as a component for the synthesis of a light stable PUR. A polyadduct of 4,4 -isopropylidenebisphenol with 2-hydroxy-4-(2,3-epoxypropyl)-benzophenone [131], polymeric HALS 115 formed from bis(2,3-epoxypropyl)ani-line and 4-amino-2,2,6,6-tetramethylpiperidine [146] or a brominated oligomer 116 used in combination with antimony trioxide as FR for PET [147] are other examples of polyaddition stabilizers. 

The elimination of an excessive dose of phenothiazines from plasma was analysed by using the novel polymeric solid-phase extraction (SPE) sorbent, strata-X-CW [191]. Strata X-CW was found to bind phenothiazines strongly, facilitating an intense organic wash and consequently allowing delivery of very clean extracts of these phenothiazines from biological matrixes. 

The temperature is adjusted to remove the alcohol by-produced by azeotropic distillation as soon as it is formed, with the ester from which it is derived (ethanol/ethyl acrylate azeotrope, for example). A third compound may be used, such as cyclohexane (ethanol/cyclohexane azeotrope j. After the catalyst system is separated, the liquid stream from the reactor is fractionated and purified under vacuum in the presence of a polymerization inhibitor (such as phenothiazine). 

A new crosslinkable polymer was synthesized by the SBP-catalyzed polymerization of cardanol [103]. When HRP was used as catalyst for cardanol polymerization, the reaction took place in the presence of a redox mediator (phenothiazine derivative) to give the polymer [104]. 

In the recent decay, there is a considerable interest in making green photopolymerizations using photosensitizers. One way to obtain nontoxic polymers through sensitization is to copolymerize compounds that can behave either as a photosensitizer or monomer with different monomers [113]. Another way is to polymerize these monomeric photosensitizers and afterward subject them to sensitize the polymerization of convenient monomers. In both ways, nontoxic and odorless polymers can be obtained after polymerization. Compounds introducing phenothiazine moiety and their polymeric analogs were found the display high efficiency in PCP of vinyl ethers and epoxides. 

Moreover, the operation can also be accelerated by employing a catalyst (cuprous chloride) in solution in an organic solvent (such as a-picoline), and by raising the temperature. Above 160 0, however, large amounts of by-products are formed 1-chloro butadiene, hydrochloric acid and especially polymers. Thus, to prevent these side reactions it is preferable to maintain a low thermal level, 105 to 125°C, and distill under partial vacuum (about 20 kPa absolute), in the presence of an inhibitor intended to prevent polymerizations from developing (phenothiazine). For a once-through conversion of 1,4-dichloro 2-butenes of about 80 per cent, molar selectivity of the 3,4-isomer exceeds 75 per cen t. 

To increase the stability of the phenothiazine dye CMEs, investigations of the electrochemical reactions of redox proteins at polymer CMEs have been undertaken. One example of such a study is the heterogeneous redox reaction of Cyt c at an electrochemically polymerized polypyrrole-methylene blue (PPy-MB) film CME. Figure 17 shows the cyclic voltammetric response that occurs during the preparation of this CME by potential... 

In Table II, mention was made of oxygen, hydroquinone and other phenolic compoimds, phenothiazine, and diphenylamine as inhibitors of the polymerization of vinyl acetate. 

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