分子内敏化鎓盐的合成及光敏性研究

二芳基碘鎓盐和三芳基硫鎓盐是阳离子聚合的光引发剂和光敏产酸物,但他们在300nm以上的光吸收很低,限制了对紫外光的利用效率。为解决此问题,本文合成了一些新的碘鎓盐和硫鎓盐,并用凝胶时间方法考察了它们的光引发效率。实验结果表明,2-苯硫基甲基,2′,4′-二甲基二苯碘鎓盐和9-蒽丙基,二苯基硫鎓盐具有特别高的光引发效率,这归之于光照时这些鎓盐发生了分子内电荷转移反应,即发生了分子内敏化。9-蒽丙基二苯硫鎓盐分子中的蒽基(An)是电子给体也是敏化基团,光照时可发生如下反应: .     

Factors influencing EB curing of epoxy matrix

The effectiveness of electron beam (EB) curing of epoxy resins was found to be influenced by catalyst. In the presence of iodonium salt (diaryl iodonium hexafluoroantimonate, C3), the EB curing of epoxy resin is easier than in the presence of triaryl sulfonium hexafluoroantimonate (C1), or triaryl sulfonium hexafluorophosphate (C2), or iron arene containing cationic catalyst (Irgacure 261). The epoxy 616 (diglycidyl ether of bisphenol A) and 648 (diglycidyl ether of phenolic novolacs) can be cured by the above onium salts catalysts C1–C3. The epoxy with glycidyl amino epoxide group (such as AG 80; AFG 90) could not be cured by onium salts catalyst. The influence of irradiation dose, temperature and the effect of impurities on curing reaction were investigated.     

Photocrosslinking of Silicones. Part XV. Cationic Photocrosslinking of α, ω, 4-Terminated Disiloxanes

Abstract

The photoinduced cationic crosslinking of α, ω-terminated disiloxanes (epoxy, vinyl ether, propenyl ether) has been investigated by means of Real-Time IR spectroscopy. A lipophilic iodonium salt and three lipophilic sulfonium salts were used as photoinitiator. The crosslinking rate is influenced by the type of α, ω-terminated disiloxane used and differed by a factor of more than 100 from the aliphatic epoxy to the vinyl ether derivatives. Moreover, the sulfonium salts were found to have a lower initiation efficiency than the lipophilic iodonium salt in the various systems studied. These results are in good agreement with the quantum yield of proton formation in a hexamethyldisiloxane/dimethoxyethane mixture. The final degree of conversion is larger with the ene derivatives than with the epoxy derivatives. The application of a kinetic method allows us to estimate the rate constant of the termination step (k_t and for the propenyl derivative the rate constant of the propagation step kp. The termination step can be described by means of a first order reaction. k_t was found to depend on the light intensity and the type of initiators used, whereas k_p is independent of the initiator used.     

Type I and type II sensitizers based on Rose Bengal onium salts

Abstract— New Rose Bengal oniurn salts containing one or two iodonium, sulfonium, phosphonium, and pyrylium ions have been prepared as part of a program to develop sensitizers which can function as Type I radical photoinitiators and Type II energy transfer donors depending on experimental conditions. The absorption spectra of the onium salts in different solvents indicate an equilibrium between tight and loose ion pairs which depends on the solvent polarity, the cation and concentration. Typical Rose Bengal photochemistry requires the structure be that of the loose ion pair in the solvent of choice. Similar factors also influence bleaching behavior, and bleaching is the result of electron transfer processes. The quantum yields of singlet oxygen production from the onium salts in polar solvents are similar to that of the parent, Rose Bengal disodium salt.     

Photocationic and radical polymerizations of epoxides and acrylates by novel sulfonium salts

Novel sulfonium salts [methyl‐, 2‐indany‐, or 1‐ethoxycarbonylethyl methyl‐2‐naphthylsulfonium hexafluorophosphate and 2‐indany‐, 1‐ethoxycarbonylethyl‐, 2‐methyl‐2‐phenylpropyl‐, 2‐phenylpropyl‐, 2‐phenylethyl‐, 2‐(4‐methoxyphenyl)‐ethyl‐, or 3‐(4‐methoxyphenyl)‐2‐propyl methylphenylsulfonium hexafluorophosphates] were synthesized by the reaction of dimethylsulfate and the corresponding sulfides followed by anion exchange with KPF₆. These sulfonium salts could polymerize epoxy monomers at lower temperatures than previously reported for benzylsulfonium salt initiators. In particular, sulfonium salts with naphthyl groups showed higher photoactivity than already reported for di(4‐tert‐butylphenyl)iodonium and triphenylsulfonium hexafluorophosphates. These sulfonium salts showed higher activity in photoradical polymerization and photocationic polymerization. The photopolymerization was accelerated by the addition of 4‐methoxy‐1‐naphthol, N‐ethylcarbazole, 2,4‐dimethylthioxanthone, phenothiazine, and 2‐ethyl‐9,10‐dimethoxyanthracene as photosensitizers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3816–3827, 2003     

Propenyl ethers. III. Study of the photoinitiated cationic polymerization of propenyl ether monomers

The effects of photoinitiator structure and variations in the experimental parameters on the rate and extent of the photoinitiated cationic polymerization of propenyl ether monomers were studied. It was found that the photoinitiators can be divided into two classes: those which exhibit an induction period and those which do not. It was demonstrated that in those propenyl ether polymerizations using iodonium salts and certain sulfonium salts which do not have an induction period, a free radical chain-induced decomposition of the onium salt takes place. The reactivity of a particular onium salt photoinitiator was shown to be related to its reduction potential. It was also shown that the structure of the monomer plays a major role in the free radical induced decomposition reaction. © 1993 John Wiley & Sons, Inc.     

A Selective C−H Deprotonation Strategy to Access Functionalized Arynes by Using Hypervalent Iodine

Described here is an efficient method to access highly functionalized arynes from unsymmetrical aryl(mesityl)iodonium tosylate salts. The iodonium salts are prepared in a single pot from either commercially available aryl iodides or arylboronic acids. The aryne intermediates are generated by ortho‐C?H deprotonation of aryl(mesityl)iodonium salt with a commercially available amide base and trapped in a cycloaddition reaction with furan in moderate to good yields. Coupling partners for the aryne intermediates beyond furan are also described, including benzyl azide and alicyclic amine nucleophiles. The regio‐ and chemoselectivity of this reaction is discussed and evidence for the spectator aryl ligand of the iodonium salt as a critical control element in selectivity is presented.     

新型锍鎓盐类光生酸剂的合成及产酸性能研究

成功合成了两种新型锍鎓盐类光生酸剂,其结构经¹1HNMR和MS分析确认,并对其基本物性及在405、365nm光下乙腈溶液中的分解及产酸性能进行了研究,通过计算得出了分解及产酸量子产率.结果表明,两种化合物有较高的热分解温度和在常用有机溶剂中有较好的溶解性;在405nm光源下,4-(9′-苯基蒽基)苯基三氟甲磺酸锍鎓盐(PAGS1)和4-(4′-N,N-二乙基-1′-苯乙烯基)苯基三氟甲磺酸锍鎓盐(PAGS2)的分解量子产率分别为10%和15%,产酸量子产率为8.1%和13%;但在365nm光源下,分解及产酸量子产率均很低,说明两种光生酸剂对于405nm波长的光较敏感,适宜作为405nm光源下的光生酸剂.     

Enhanced detection of sulfo-peptides as onium salts in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

A new two-component system, consisting of a matrix and an onium salt as comatrix, is described for detection of sulfo-peptides in the positive mode by matrix-assisted desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Binary iodonium salts were superior to quaternary phosphonium salts in terms of suppression of desulfation and salt formation with the carboxyl group. Of the iodonium salts examined, bis(4-tert-butylphenyl)iodonium (BTI) hexafluorophosphate and bromide were most effective in giving intensive molecular ion signals in the form of [M(BTI)+BTI](+). The conditions optimized for O-sulfated tyrosine-containing peptides could be applicable for O-sulfated serine- and threonine-containing peptides. In the case of a phospho-peptide, a molecular ion appeared more intensively as a proton adduct than as a BTI adduct.     

(4-羟基苯基)甲基苄基硫鎓六氟锑酸盐的合成及表征

以4-羟基苯硫酚和氯苄为原料、三乙胺为缚酸剂,制备了4-苄硫基苯酚;4-苄硫基苯酚在甲苯溶液中,经硫酸二甲酯甲基化制备了（4-羟基苯基）甲基苄基硫鎓硫酸盐;室温甲醇溶剂中,与六氟锑酸钠离子进行交换合成了目的产物（4-羟基苯基）甲基苄基硫鎓六氟锑酸盐。通过紫外光谱和核磁共振测定,对产物进行了结构鉴定。总收率大于75%。     

Promotion of the photoacid generation performance of sulfonium salts by inhibiting the isomerization of conjugated systems using a cyclization strategy

This work describes an original structure−reactivity relationship within a series of sulfonium salts synthesized using a cyclization strategy. The new sulfonium salt comprises a stilbene subunit decorated with a combination of cyclized structure, that is, carbocyclic ring, furan ring, and thiophene ring, to inhibit the isomerization of double bond systems. The photoacid generation efficiency of such cyclized stilbene derivative sulfonium salts is mainly modulated by the five-membered ring structures and the substituent as confirmed by photodegradation, in situ nuclear magnetic resonance, and cyclic voltammetry. Such cyclization drastically regulates the population of highly reactive excited singlet species and thus enhances the photoacid generation performance of the sulfonium salts by more than one order of magnitude within the series, especially when introducing oxygen to form the benzofuran ring structure. Given this amplified photoreactivity, the application potential of the photoinitiated cationic polymerization of the sulfonium salts was evaluated at different irradiation wavelengths.     

Charge transfer complexes as dual thermal/photo initiators for free-radical frontal polymerization

Frontal polymerization is a process in which a localized reaction zone propagates from the coupling of thermal transport and the Arrhenius rate dependence of an exothermic polymerization; monomer is converted into polymer as the front passes through an unstirred medium. Herein we report the first study of charge transfer complexes (CTCs) as photo/thermal initiators for free-radical frontal polymerization. Front velocity was studied as a function of mole ratio between an aromatic amine, such as dimethyl-p-toluidine or dimethylaniline, and an iodonium salt. It was found that the front velocity reached a maximum at a certain mole ratio of amine to iodonium salt. The velocity remained constant upon increasing the ratio of amine to iodonium salt past this critical ratio. Fronts were also studied using N-phenyl glycine as an electron donor, but its utility was limited by low solubility. Lastly, the steric and electronic effects of the iodonium salt and counter anion were explored. It was found that CTCs using iodonium salts with less nucleophilic anions gave higher front velocities. In terms of intrinsic reactivity, the CTC composed of N,N-dimethyl-p-toluidine and bis[4-(tert-butyl)phenyl]iodonium tetra(nonafluoro-tert-butoxy)aluminate gave the highest front velocity per molal of iodonium salt.     

Electroorganic chemistry—XV : Electroreduction of sulfonium and ammonium salts. Formation of sulfonium ylids

In the electroreduction of sulfonium and ammonium salts, sulfonium ylid was generated from the sulfonium salt, whereas in the case of the ammonium salt, nitrogen ylid was not formed but the N+C bond was reductively cleaved. On the basis of the controlled potential electrolysis, it seems acceptable that the mechanism of formation of sulfonium ylid involves the direct electron transfer to the sulfonium salt as the initiation step.     

β-(Trifluoromethyl)vinyl sulfonium salts: preparation and reactions with active methylene and methenyl compounds

Two trifluoromethyl-substituted building blocks β-(trifluoromethyl)vinyl sulfonium salts 1 and 2 were developed. Reactions of β-(trifluoromethyl)vinyl sulfonium salt 1 with active methylene compounds containing electron-withdrawing groups using DBU as the base in DMSO occurred to give trifluoromethyl-substituted cyclopropane derivatives 7 as the major products. In contrast, reactions of β-(trifluoromethyl)vinyl sulfonium salt 2 with active methylene compounds occurred with the migration of one of the electron-withdrawing groups to give the products 8 as the major products when NaH was used as the base in DMSO. Moreover, when NaH was used as base in THF/CH(2)Cl(2) at -78 °C, reaction of β-(trifluoromethyl)vinyl sulfonium salt 1 gave trifluoromethyl-substituted 2,3-dihydrofuran derivatives 9 as the major products. A working mechanism was proposed to explain the different behaviors of the β-(trifluoromethyl)vinyl sulfonium salts 1 or 2 with active methylene compounds under these different conditions.     

Electrostatic and Non‐covalent Interactions in Dicationic Imidazolium–Sulfonium Salts with Mixed Anions

A series of thioether‐functionalised imidazolium salts have been prepared and characterized. Subsequent reaction of the thioether‐functionalised imidazolium salts with iodomethane affords imidazolium–sulfonium salts composed of doubly charged cations and two different anions. Imidazolium–sulfonium salts containing a single anion type are obtained either by a solvent extraction method or by anion exchange. The imidazolium–sulfonium salts undergo a methyl‐transfer reaction on exposure to water, giving rise to a new, singly charged imidazolium salt with iodide introduced at the 2‐position of the imidazolium ring. Crystal structures of some of the imidazolium–sulfonium salts were determined by X‐ray crystallography providing the topology of the interactions between the dications and the anions. Electrospray ionization mass spectrometry and quantum‐chemical calculations were used to rationalise the relative strength of these interactions.     

Grafting of a bicycloorthoester onto polymers bearing sulfonium salt structures

Graft copolymerization of a bicycloorthoester (BOE) with polymer-supported sulfonium salts was studied. Several polymer-supported sulfonium salts were prepared by the homopolymerizations of p-vinylbenzyl tetramethylenesulfonium hexafluoroantimonate ( 2 ) and 4-(p-vinylphenyl)butyl tetramethylenesulfonium hexafluoroantimonate ( 3 ), and by the copolymerizations of 2 with some vinyl monomers (n-butyl vinyl ether, styrene, acrylonitrile, and p-styrenesulfonic acid potassium salt). These sulfonium salts could initiate the polymerization of BOE to give grafted polymers. Temperature dependences of the catalytic activity of them were not so dramatic as that of benzyl tetramethylenesulfonium hexafluoroantimonate ( 1 ), but the activities of them were higher than that of 1 at temperatures lower than 80°C. The conversion of BOE in the polymerizations with these polymer initiators was ca. 30–70% at 120°C for 7 h. An effect of the comonomer structure on the catalytic activity was observed and styrene was the best comonomer for 2 in terms of the reactivity of the copolymer. The spacer-modified sulfonium salt (homopolymer of 3 ) was slightly lower than polymer-supported benzyl type sulfonium salt (homopolymer of 2 ) in the catalytic activity.     

A Direct Route to C-Vinylaziridines: Reaction of N-Sufonylimines with Allylic Ylides under Phase-Transfer Conditions or with Preformed Ylides at Low Temperature

Allylic sulfonium salts 3, 5, 7, 11, 12, 13, and arsonium salt 14 react with aromatic, heteroaromatic, and alpha,beta-unsaturated N-sulfonylimines under solid-liquid phase-transfer conditions in the presence of KOH at room temperature to produce, respectively, vinyl-, (beta-phenylvinyl)-, and [beta-(trimethylsilyl)vinyl]aziridines in excellent yields within several minutes. In some cases, pyrroline compound 9 is obtained as a minor product. This aziridination reaction has also been carried out with preformed ylides, generated from sulfonium salts 3, 7, arsonium salt 14, and telluronium salts 15, 16 with a base in THF at -78 degrees C. In most examples, quantitative yields were achieved. However, the trans/cis selectivity of the reaction was not high in either case. A semistable allylic sulfonium ylide, i.e., dimethylsulfonium 3-(trimethylsilyl)allylide, was found to not undergo an expected [2,3]-sigma-rearrangement and so can also be used in this reaction.     

Nickel-Catalysed Cross-Electrophile Coupling of Benzyl Bromides and Sulfonium Salts towards the Synthesis of Dihydrostilbenes

A nickel-catalysed reductive cross-coupling reaction between benzyl sulfonium salts and benzyl bromides is reported. Simple, stable and readily available sulfonium salts have shown their ability as leaving groups in cross-electrophile coupling, allowing the formation of challenging sp³–sp³ carbon-carbon bonds, towards the synthesis of interesting dihydrostilbene derivatives. In addition, benzyl tosyl derivatives have been demonstrated to be suitable substrates for reductive cross-coupling by in-situ formation of the corresponding sulfonium salt.     

香豆素酮类化合物的瞬态研究——Ⅲ.香豆素酮和碘鎓盐间的电子转移

本工作采用激光闪光光解法对香豆素酮类化合物敏化碘鎓盐化合物问题进行了研究。结果表明:碘鎓盐化合物能通过电子转移机理猝灭香豆素酮的激发三重态。工作中还用甲基紫精(PQ²⁺)为模型化物,观察到它也能使香豆素酮的三重态猝灭,同时可看到在位于610nm处的PQ⁺生成。这些结果说明,在发生电子转移的反应中香豆素酮是电子给体,按Weller公式的计算结果也表明它们之间可发生电子转移反应。     

荧烷染料/二芳基碘鎓盐同步光生色和光聚合体系

荧烷染料(FR)和二芳基碘盐(On⁺X^-)组成的体系,在光作用下,通过激发态的荧烷染料与碘盐之间发生电子转移反应,生成开环结构的荧烷染料有色体,伴随发生盐的光解反应,生成活性引发自由基碎片。该体系不仅可有效地引发烯类单体的聚合反应,也可同步发生光生色作用,产生较高的色密度。进一步研究了二芳基碘盐的取代基不同碳链长度和不同对离子及浓度诸因素,在光固化体系中对生色反应的影响。同时FR/On⁺X^-体系引发光交联形成的有色薄膜具有良好的色稳定性。