Tetramethylammonium phenyltrialkylborates in the photoinduced electron transfer reaction with benzophenone. Generation of alkyl radicals and their addition to activated alkenes

Polykarpov, Alexander Y.; Neckers, Douglas C.

doi:10.1016/0040-4039(95)01055-m

Cited by 20 publications

(31 citation statements)

References 3 publications

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“…This was confirmed by measuring the quantity of an adduct formed during irradiation of a deaerated solution containing phenyltrialkylborate and methyl methacrylate in benzene/acetonitrile [23]. The obtained result was in good agreement with the Polykarpov and Neckers [20] studies.…”

Section: Resultssupporting

confidence: 72%

“…The latter is the most likely initiator of acrylates polymerization. What is more, the studies of Necker et al [20] revealed that in the case of phenyltrialkylborates, the second product formed after an electron transfer process, phenyldialkylborane, is also capable of initiating a chain radical reaction. It can react either with the oxygen centered radical product of addition of the alkyl radical to the vinyl bond of monomers or with the excited state of the sensitizer [21] forming additional radicals.…”

Section: Resultsmentioning

confidence: 99%

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Factors affecting the TMPTA radical polymerization photoinitiated by phenyltrialkylborates paired with tri-cationic hemicyanine dye. Kinetic studies

Jędrzejewska

2013

Colloid Polym Sci

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This article introduces tri-cationic hemicyanine dye employed as a visible-light photoinitiator of acrylic monomers polymerization. This dye, in combination with borate anions, was found to be a very effective photoinitiating system. The kinetics of trimethylolpropane triacrylate polymerization was studied by a microcalorimetric method. The photoredox pair concentration, the co-initiator structure as well as the light intensity strongly affected the progress of the polymerization, leading, for example, to an increase in the polymerization rate and quantum yield of the process. The efficiency of these photoinitiators was discussed on the basis of the free energy change for electron transfer from a borate anion to an excited hemicyanine dye cation. The ∆Gel values were estimated for photoredox pairs containing a series of phenyltrialkylborate anions and one styrylpyridinium dye cation. The relationship between the rate of polymerization and the free energy of activation for electron transfer reaction gives the dependence predicted by the classical theory of electron transfer. The photoinitiating abilities of the selected novel photoredox pairs (BPB61, BPB7, BPB8, and BPB9) are comparable with the photoinitiating efficiency of commercially available photoinitiators.

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Factors affecting the TMPTA radical polymerization photoinitiated by phenyltrialkylborates paired with tri-cationic hemicyanine dye. Kinetic studies

Jędrzejewska

2013

Colloid Polym Sci

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“…The method of borate salts synthesis using alkyllithium reagents is similar to that published by Neckers and co-workers [26,27]. Tetramethylammonium phenyltrimethylborate (B5) and tetramethylammonium phenyltriisopentylborate (B9) were prepared from the reaction of dichlorophenylborane with methyllithium followed by cation exchange.…”

Section: Synthesismentioning

confidence: 99%

“…Simple synthetic procedures have been developed to prepare suitably substituted stable phenyltrialkylborate tetramethylammonium salts [26,27]. The synthetic approaches that have been applied are outlined below and are based on the addition of alkyl or phenyllithium reagents to a triorganylborane or organoboranylhalides.…”

Section: Synthesismentioning

confidence: 99%

Synthesis of tetramethylammonium phenyltrialkylborate salts by the addition of alkyllithium reagents to a triorganylborane or organoboranylhalides

Pietrzak

Jędrzejewska

2011

Journal of Organometallic Chemistry

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“…In fact, in model studies with triphenylbutylborate co‐initiators, there has been no evidence whatsoever for a free phenyl radical 4. However, tetraarylborates and, in particular, tetraphenylborates are more stable and easier to make than the corresponding arylalkylborates; this suggests an important advantage 4, 5…”

Section: Introductionmentioning

confidence: 99%

Applicability of hemicyanine phenyltrialkylborate salts as free‐radical photoinitiators in the visible‐light polymerization of acrylate

Jędrzejewska

Pietrzak

2011

J of Applied Polymer Sci

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The photoinitiation ability of photoredox pairs composed of a hemicyanine dye cation and different borate anions for the radical polymerization of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate was investigated. In such a system, the excited dye chromophore is reduced by different tetraorganylborate anions. Upon irradiation at 488 nm, reductive carbon-boron bond cleavage occurs, producing reactive radicals, which start the chain reaction. The efficiency of bond-breaking processes was found to be dependent on the nature of both the acceptors and the donors. The experimental results show that the photoinitiating ability of the tested photoredox pairs were controlled by both the driving force of the electron-transfer process between the electron donor and the electron acceptor and the reactivity of the free radical that resulted from the secondary reactions occurring after the photoinduced electron-transfer process. Using the nanosecond flash photolysis method, we studied the spectral and kinetic characteristics of the triplet state of cyanine dye and determined the rate constants of the triplet quenching by phenyltrialkylborate salts. The results obtained show that the tetramethylammonium phenyl-tri-n-butylborate (TB7) has a faster electron-transfer rate than the tetramethylammonium n-butyltriphenylborate (TB2) salt, which bore only one butyl group attached to the boron. The relative initiator efficiency of the triphenylbutylborate salts, as compared to the corresponding phenyltrialkylborate salts with a common chromophore, was determined.

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Tetramethylammonium phenyltrialkylborates in the photoinduced electron transfer reaction with benzophenone. Generation of alkyl radicals and their addition to activated alkenes

Cited by 20 publications

References 3 publications

Factors affecting the TMPTA radical polymerization photoinitiated by phenyltrialkylborates paired with tri-cationic hemicyanine dye. Kinetic studies

Factors affecting the TMPTA radical polymerization photoinitiated by phenyltrialkylborates paired with tri-cationic hemicyanine dye. Kinetic studies

Synthesis of tetramethylammonium phenyltrialkylborate salts by the addition of alkyllithium reagents to a triorganylborane or organoboranylhalides

Applicability of hemicyanine phenyltrialkylborate salts as free‐radical photoinitiators in the visible‐light polymerization of acrylate

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