Photoreduction of aromatic ketones by amines. Studies of quantum yields and mechanism

Cohen, Saul G.; Chao, H

doi:10.1021/ja01003a029

Cited by 117 publications

(54 citation statements)

References 1 publication

(1 reference statement)

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“…This parallels the results of Cohen and Chao (24) who found that the rate of photoreduction of benzophenone by tertiary amines increased on dilution of the amine with b e n~e n e .~ These authors ascribed the increase to the formation of light absorbing transients in the more concentrated solutions of the amine. It should be noted that there is also a maximum in the rate as the benzil concentration is varied, Table 1.…”

Section: Resultssupporting

confidence: 87%

“…Further evidence that the amines suppressed benzil pinacol formation by associating with the ketyl radicals was obtained in the following way. It is known that hydrocarbon quenchers are much less efficient in the photoreduction of benzophenone in amines than in alcohols (24,26).…”

Section: Resultsmentioning

confidence: 99%

“…Whenever there is triethylamine present there are three products besides the pinacol, one of them being the coupling product between the amine derived radical and the ketyl radical of the p-hydroxybenzophenone. Coupling in the presence of amines has been pointed out by Cohen et al (5).…”

Section: -Hydroxybenzil Irradiationsmentioning

confidence: 90%

“…There has been much recent work on the photolysis of various benzophenones and of fluorenone using tertiary amines as solvents and hydrogen donors (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). This work has shown that those ketones which do not undergo photoreduction in 2-propanol because the lowest lying excited state is unreactive toward hydrogen abstraction, are photoreduced in triethylamine and other tertiary amines.…”

Section: Introductionmentioning

confidence: 99%

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The Photolysis of 4-Hydroxybenzil and the Effect of Triethylamine on the Photolysis of Benzil and 4-Hydroxybenzil

Bunbury¹,

Chan²

1972

Can. J. Chem.

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Benzil is photoreduced in neat triethylamine and mixtures of triethylamine and 2-propanol. In neat 2-propanol the principal products are; benzil pinacol, 20%; benzoin benzoate, 19%; benzoin, 18%; and benzoic acid, 12%. When the amine concentration is as low as 0.2 mM the benzil pinacol formation is almost completely suppressed. At amine concentrations higher than 0.36 mM the principal product is benzoin, 80%. At intermediate amine concentrations benzoin benzoate is important. The rate of benzil disappearance reaches a maximum and then declines as either the benzil concentration in triethylamine is increased or the amine concentration in 2-propanol is increased.4-Hydroxybenzil is not photoreduced by 2-propanol. It is reduced by triethylamine. The quantum yield of disappearance is 0.04 at a concentration of 47.8 mM and in solutions containing at least 0.36 M of amine. 4-Hydroxybenzoin is the principal product but at low starting 4-hydroxybenzil concentrations 4,4′-dihydroxybenzil is important. A rate maximum is also observed in this case.4,4′-Dihydroxybenzil is not photoreduced by 2-propanol. It does undergo photoreaction in neat triethylamine but no products were isolated.Triethylamine also appears to suppress biacetyl pinacol formation in the photoreaction of biacetyl with 2-propanol.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: -Hydroxybenzil Irradiationsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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The Photolysis of 4-Hydroxybenzil and the Effect of Triethylamine on the Photolysis of Benzil and 4-Hydroxybenzil

Bunbury¹,

Chan²

1972

Can. J. Chem.

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“…그러나 CQ는 색상이 노란색이어서 레진의 최종적인 심미성에 영향을 주기 때문에 CQ의 농도를 높이는데 한계 가 있고, 결과적으로 중합정도와 깊이가 제한되는 문제를 안고 있다 6) . 이에 따라 CQ의 농도를 증가시키지 않고 중합 효율을 개선시키기 위해 다른 중합개시제 7-9) 또는 환원제 10,11) 를 사용하거나, 다른 중합법 12) 을 사용함으로써 중합효율 을 개선하기 위한 많은 시도가 있었다. 예를 들면, PPD (1-pheny1-1,2-propanedione)는 CQ만큼 광중합 개시제 로 효과가 있었고, CQ와 함께 사용되었을 때, 시너지 효과 가 있었다는 보고가 있으며 13) , Inano 등 14) 은 몇 가지 효소 들이 광중합개시제로 사용될 수 있다고 한 바도 있다.…”

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Microleakage of the experimental composite resin with three component photoinitiator systems

Kim

Shin

2009

J Korean Acad Conserv Dent

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This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included.Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 μ m) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A -0.5%, 0%, 1% / Group B -2%, 0.2%, 2% / Group C -0.2%, 1%, 0.2% / Group D -1%, 1%, 2%.Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/cm 2 . Teeth were thermocycled fivehundred times between 50℃ and 550℃ for 30s at each temperature.Electrical conductivity (μ A) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method.Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (μ A)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41).Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage. [J Kor Acad Cons Dent 34(4): [333][334][335][336][337][338][339] 2009]

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Formation of Alcohols and Phenols by Reduction of Carbonyl Compounds

Larock,

Raminelli

2018

Comprehensive Organic Transformations

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Photoreduction of aromatic ketones by amines. Studies of quantum yields and mechanism

Cited by 117 publications

References 1 publication

The Photolysis of 4-Hydroxybenzil and the Effect of Triethylamine on the Photolysis of Benzil and 4-Hydroxybenzil

The Photolysis of 4-Hydroxybenzil and the Effect of Triethylamine on the Photolysis of Benzil and 4-Hydroxybenzil

Microleakage of the experimental composite resin with three component photoinitiator systems

Formation of Alcohols and Phenols by Reduction of Carbonyl Compounds

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