Benzoin Methyl Ether Research Articles

Studies on the light‐focusing plastic rod. XIII. Photocopolymerization of methyl methacrylate–vinyl esters of aromatic carboxylic acid

AbstractThe light‐focusing plastic rod (LFR) was prepared by the photocopolymerization of methyl methacrylate (MMA) with vinyl phenylacetate (VPAc) and vinyl benzoate (VB), using benzoyl peroxide (BPO), benzoin (BN), and benzoin methyl ether (BME) as an initiator. The LFR with high transparency and steep refractive‐index distribution was obtained using the MMA–VPAc pair and the BME. The difference in the index distributions under BPO, BN, and BME initiations was clarified in terms of the photoinitiation rate and the accompanying thermal polymerization during the photocopolymerization process. The light scattering intensity from the LFR was related to the heterogeneity of the copolymer composition and the compatibility between the M1 and M2 polymers. The comparison of the light scattering theory with the experimental data indicated that the much less scattering intensity from the MMA–VPAc LFR than the MMA–VB LFR should be attributed to the good compatibility between the MMA and VPAc polymers, and scarcely attributed to the index difference between the VPAc and VB polymers.

Photoinitiated polymerization of methyl methacrylate with benzoin methyl ether. III. Independent photogeneration of the ether radical

AbstractEvidence is presented for initiation of MMA polymerization by the α‐methoxybenzyl (ether) radical, photogenerated by H abstraction from benzyl methyl ether, utilizing benzophenone as the H‐ab‐stracting agent. The results support previous reports on the initiating ability of ether radical, photogenerated from 14C‐labeled benzoin methyl ethers. Independent generation of one or both of the radicals derived from unsymmetrical initiators is more broadly applicable. The potential utility of this technique for providing insights into the photoefficiencies of commercially important photoinitiators, which produce initiator radicals by intramolecular bond cleavage, is discussed.

Studies on the light-focusing plastic rod 12: The GRIN fiber lens of methyl methacrylate–vinyl phenylacetate copolymer

The light-focusing plastic rod (LFR) and fiber (LFF) were fabricated by photocopolymerization of methyl methacrylate (MMA) with vinyl phenylacetate (VPAc). The MMA-VPAc LFR has much higher clarity than that of the MMA-vinyl benzoate LFR reported previously. Using the benzoin methyl ether as the initiator, which initiates photopolymerization preferentially, led to a much steeper index distribution than using benzoyl peroxide, which initiates thermal- and photochemical polymerization simultaneously. The relationships between preparation condition and optical characteristics were clarified in terms of the index distribution, light scattering, lens function, and attenuation of light transmission.

Low-temperature embedding procedures applied to chloroplasts

Pea and spinach chloroplasts were fixed with glutaraldehyde and dehydrated with ethylene glycol at 0°C. In some experiments dehydration was achieved by the resin itself. The material was infiltrated at temperatures between −35 and 0°C with mixtures of hydroxypropylmethacrylate and butylmethacrylate or a mixture of methacrylates and acrylates containing crosslinking agents. Polymerization was achieved, at the same temperature as the infiltration, using uv light and benzoin methyl ether as the catalyst. In uranyl acetate stained sections of specimens embedded at −35°C the thylakoid membranes appeared light between the strongly and evenly stained partition gaps. Dark spots of various shapes appeared in the middle of each thylakoid intercalated at irregular intervals by closely apposed membrane segments. In specimens embedded at −18 or 0°C the dark spots were replaced by a continuous dark layer identical to the partition gaps. The patterns seen in sections of embedded chloroplasts also appeared in specimens prepared by cryoultramicrotomy. The structural patterns described deviate markedly from those obtained when a conventional procedure is applied to the material mentioned.

Photoinitiators and photoinitiation, 1. Vinyl polymerization photoinitiated by benzoin methyl ether.

Die Makromolekulare ChemieVolume 180, Issue 10 p. 2531-2537 Short Communication Photoinitiators and photoinitiation, 1. Vinyl polymerization photoinitiated by benzoin methyl ether†.‡ Hendrik J. Hageman, Corresponding Author Hendrik J. Hageman Akzo Research, Corporate Research Department, Arnhem, The NetherlandsAkzo Research, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorFranciscus P. B. Van der Maeden, Franciscus P. B. Van der Maeden Akzo Research, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorPetrus C. G. M. Janssen, Petrus C. G. M. Janssen Akzo Research, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this author Hendrik J. Hageman, Corresponding Author Hendrik J. Hageman Akzo Research, Corporate Research Department, Arnhem, The NetherlandsAkzo Research, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorFranciscus P. B. Van der Maeden, Franciscus P. B. Van der Maeden Akzo Research, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this authorPetrus C. G. M. Janssen, Petrus C. G. M. Janssen Akzo Research, Corporate Research Department, Arnhem, The NetherlandsSearch for more papers by this author First published: October 1979 https://doi.org/10.1002/macp.1979.021801031Citations: 43 † α-Methoxydeoxybenzoin. ‡ Dedicated to Prof. Dr. E. Havinga on the occasion of his 70th birthday and his retirement from the Chair of Organic Chemistry at the University of Leiden. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume180, Issue10October 1979Pages 2531-2537 RelatedInformation

Flash photolysis investigation on primary processes of the sensitized polymerization of vinylmonomers. III. Photoreactions of benzoin compounds and stationary polymerization experiments

AbstractBenzoin (B), benzoinacetate (BA), benzoinmethylether (BME) and benzoinisopropylether (BIPE) were irradiated at room temperature in benzene solution in the presence of styrene (St), methyl methacrylate (MMA), vinylacetate (VAc) or acrylonitrile (AN). Flash photolysis experiments at λ=347 nm yielded (a) rate constants kq (in 1 mol‐1s‐1) of the reaction between excited sensitizers and monomers: 8·109 (B/St), 5·108 (B/MMA), 5·109 (BA/St), 8·108 (BA/MMA); (b) rate constants KR.+M (in 1mol‐1 s‐1) of the reaction between sensitizer radicals and monomers: about 1.5·105 (BME/St, BME/VAc, BA/VAc, B/VAc), 9· 104 (BME/MMA), 2·104 (BME/AN). The reaction R·+M caused in certain cases (B/St, B/VAc, BME/St) the formation of an additional optical absorption after the flash.Stationary irradiations at λ>320 nm of monomer solutions (5mol/1) showed that BA is least effective. Rates of polymerization increased in the series BA<B<BIPE<BME. For the systems containing St or MMA it was found that ϕi=i+0.6αR (ϕi=quantum yield for the initiation of kinetic chains, αR =fraction of triplets converted to radicals). The fraction of radicals starting kinetic chains is ca. 0.3 in these cases.

Kinetic analysis of photopolymerization reaction of lauryl acrylate with a photoinduced chemical reaction calorimeter

AbstractCalorimetric studies on kinetics of photopolymerization reactions made previously have been limited by the structures of the calorimeters. This report suggests a thermal‐leak type of calorimeter for carrying out kinetic analysis of the photopolymerization reaction. The method was applied to the photopolymerization system consisting of lauryl acrylate and benzoin methyl ether. The results obtained illustrate the utility of this apparatus.

Flash photolysis investigation on primary processes of the sensitized polymerization of vinyl monomers: 2. Experiments with benzoin and benzoin derivatives

Benzene solutions of benzoin (B), benzoin acetate (BA), benzoinmethyl ether (BME) and benzoinisopropyl ether (BIPE) were irradiated with 0.1 or 25 nsec flashes of 347.1 nm light at room temperature. With B and BA optical absorptions due to radical precursors were detected. The first order decay constants of these absorptions are 1.1 × 10 8 sec −1 (B) and 5.3 × 10 7 sec −1 (BA). The radical spectra decayed according to second order laws. In the case of B only one mode of decay was observed which accounts for the major part of the reaction (benzaldehyde formation by disproportionation of unlike radicals). During the experiments with BA, BME and BIPE two modes of radical-radical reactions were detected. Styrene was found to react with the rapidly decaying species with k M = (1.3 ± 0.2) × 10 5 M −1 sec −1, but did not react with the slowly decaying species. By considering the end product analyses of other authors it was concluded that the rapidly decaying mode of the absorption decay is due to the combination of benzoyl radicals forming benzil. The slowly decaying mode was assigned to the combination of alkoxybenzyl radicals (in the case of BME and BIPE) or of acetonbenzyl radicals (in the case of BA) forming pinacol derivatives. The rate constants of the reaction of naphthalene with triplet excited benzoin (7.7 ± 0.8) × 10 9 M −1 sec −1 and benzoin acetate (5.0 ± 0.5) × 10 9 M −1 sec −1 were determined.

Photoinitiated polymerization of methyl methacrylate and methyl acrylate with 14C‐labeled benzoin methyl ethers

AbstractThree 14C‐labeled benzoin methyl ether (α‐methoxy‐α‐phenylacetophenone) derivatives were utilized as photoinitiators in the polymerization of methyl methacrylate (MMA) and methyl acrylate (MA). The results of polymer end‐group analysis are in accord with a mechanism of benzoin ether photocleavage into initiator radicals and dispute earlier labeling studies which were interpreted as evidence for copolymerization of excited‐state benzoin ethers with reactive monomers. In MMA polymerization, the results indicate a preference for termination by disproportionation (∼60%) and provide evidence for primary radical termination at 0.041M photoinitiator (optically dense solutions) in neat MMA. Evidence for chain branching by initiator radical hydrogen abstraction from poly(methyl acrylate) (PMA) is also presented. The benzoyl and α‐methoxybenzyl radicals, produced on photolysis of benzoin methyl ether, appear to be equally effective in both initiation and hydrogen‐abstraction processes. Quantum yields at 366 and 313 nm indicate the absence of a wavelength effect.

Thermally Regenerable Ion-Exchange Resins by Photografting

Abstract Crosslinked polymer beads containing regions of acidic and basic groups are the preferred structures for the efficient operation of a thermally regenerable ion-exchange process. Such systems can be prepared by various methods. Here the approach of using polymers and copolymers containing photo-labile groups as grafting sites is described. The polymers studied were polytriallylamine hydrochloride (polyTAA) and copolymers of propyldiallylamine hydrochloride (PDAA) and allyl benzoin methyl ether (ABME), of ABME and acrylic acid (AA), and of ABME and methyl acrylate (MA). The maximum amount of photografting of MA onto polyTAA was 12%. Very little photografting of MA onto PDAA:ABME copolymers was obtained. Photografting of TAA to AA:ABME and to MA:ABME copolymers occurred readily by using radiation of 360 nm wavelength, with the best yields of photografted polymer being about 60% when a MA:ABME copolymer was irradiated in a suspension. The effect of suspending medium, stirring rate, irradiation time, ...

Polymerization of Methyl Methacrylate Initiated by the Benzoin—Pyridine—Carbon Tetrachloride System

A mixture of benzoin, pyridine, and carbon tetrachloride has been found to be an effective initiation system for the polymerization of methyl methacrylate (MMA). The lack of any one component resulted in a remarkably slower rate of polymerization. The α-hydroxy ketone group in benzoin has been shown to be necessary to initiate the polymerization of MMA, by comparison with the results of the polymerizations by benzil, hydrobenzoin, or benzoin methyl ether instead of benzoin. The activation energy of the initiation reaction was calculated to be 12.8 kcal/mol from the overall activation energy of 11.3 kcal/mol, using the values of the propagation and termination energy in the literature. The small activation energy of initiation suggested that the initiation reaction in this system proceeds through a redox mechanism. The initiation mechanism was proposed on the basis of the results of the kinetics and the product analysis.

The mechanism of CO loss in the electron impact‐induced fragmentation of benzoin and its methyl ether

AbstractThe electron impact‐induced fragmentation of benzoin methyl ether gives rise to the formation of an m/e 91 fragment ion which is not present in the mass spectrum of benzoin. Deuterium and 13C labelling, as well as low energy experiments, revealed that this ion is formed from [M – benzoyl]+ by transfer of both the ether methyl group and the hydrogen atom from the α‐position to the adjacent phenyl ring followed by loss of CO and hydrogen.

Benzoin‐ and benzoin methyl ether‐sensitized photopolymerization of styrene and methyl methacrylate: Quantum yields and mixing effects

AbstractStyrene and methyl methacrylate have been polymerized in a batch photoreactor using two sensitizers–benzoin (C6H5COCHOHC6H5) and benzoin methyl ether (C6H5COCHOCH3C6H5)–and light with a peak intensity at 366 nm. Primary quantum yields have been calculated for each monomer‐sensitizer combination. Effects of mixing on the rate of polymerization and product molecular weight distribution have been determined and correlated with a two‐region reactor model.

Photoinduced Reactions. LXXIII. Solvent Dependence in the Photochemical Reaction of α-Nitroepoxides

Abstract The photochemical reaction of α-nitroepoxides showed marked solvent dependence. The photolysis of (1,2-epoxy-2-nitropropyl)benzene (I) in 2-propanol led to the formation of three products 1-phenyl-1-isopropoxy-2-propanone (IIb), 1-phenyl-1,2-propanedione oxime (III) and 1-hydroxy-1-phenyl-2-propanone oxime (IV), whereas on irradiation in ether I gave exclusively IV. However, in t-butyl alcohol, benzene, acetone, acetonitrile or n-hexane, I was not susceptible to photolysis. The photolysis of α,α′-epoxy-α-nitrobibenzyl (V) in ether gave benzoin oxime (VII) in addition to benzaldehyde and benzoic acid, whereas in methanol it gave benzoin methyl ether (VI) in the dark. These reactions are interpreted in terms of effects of the acidity and hydrogen-donating property of solvents on the excited α-nitroepoxides. The pyrolysis of I and V were also examined.

Mechanisms and relative efficiencies in radical polymerization photoinitiated by benzoin, benzoin methyl ether and benzil

Contrary to widely held views, detailed studies of light absorption characteristics, reaction rates, and molecular weights in radical polymerization of methyl methacrylate photoinitiated by benzoin and benzoin methyl ether indicate that the two photoinitiators have comparable efficiencies; benzil is much less efficient. Mechanisms for initiation, and possible termination processes, for systems involving all three photoinitiators are discussed in the light of results from studies of radical characterization by the spin trapping technique.

Radical intermediates in the photochemical decomposition of benzoin and related compounds

The radical scavenging technique used in conjunction with e.s.r. spectroscopy has been employed to characterise radicals produced by photolysis of benzoin, benzoin methyl ether, and benzil with reference to their relative efficiencies as photoactivators for radical polymerization. Radicals trapped by N-oxides and nitroso-compounds indicate that while benzoin and its methyl ether are photochemically cleaved in a similar manner, the latter produces radicals more efficiently. Possible mechanisms are presented.