Photosensitivity of methylene chloride, stimulated by free radicals

Mikheev, Yu. A.; Pustoshnyi, V. P.; Toptygin, D.Ya.

doi:10.1007/bf00921733

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…The reaction is indicated by a decrease of the DBPHZ absorption bands as well as the emergence of a band peaking at 466 nm. Reactions of dichloromethane with solutes in the presence of UV‐light have been described before [42,43] . Tracing the absorption changes with time (or photon equivalents, cf.…”

Section: Resultsmentioning

confidence: 99%

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The Photophysics of Dibenzo[a,j]phenazine

et al. 2021

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The photophysics of dibenzo [a,j]phenazine (DBPHZ) in solution was investigated by steady-state and time-resolved spectroscopy. The nature of the solvent (methanol, acetonitrile, dichloromethane and cyclohexane were considered) only weakly affects the photophysical properties. The first excited singlet state features a lifetime of the order of 1 ns. Its fluorescence emission is centered around 420 nm and occurs with moderate yields of � 0.1. The lowest triplet state is populated with yields of � 0.3. Quantum chemical computations suggest that a 3 np * state energetically close to the primarily excited singlet state is responsible for the efficient intersystem crossing towards the triplet manifold.

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Section: Resultsmentioning

confidence: 99%

“…Reactions of dichloromethane with solutes in the presence of UV-light have been described before. [42,43] Tracing the absorption changes with time (or photon equivalents, cf. Figure 2, insert) reveals rather complex reaction kinetics.…”

Section: Steady-state Propertiesmentioning

confidence: 99%

The Photophysics of Dibenzo[a,j]phenazine

et al. 2021

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“…As a result of the reaction sequence (1) to (4), radicals C • HCl 2 and C • H 2 Cl from the solvent are generated, with the former radical being dominant. These radicals can either recombine or disproportionate, or participate in other radical reactions (Scheme , reaction (5)) or in the reactions (6) and (7) with traces of water in the presence of oxygen. Reaction (6) gives phosgene, which decomposes in the reaction with H 2 O (reaction (7)) to afford HCl.…”

Section: Discussionmentioning

confidence: 99%

“…Despite the relatively low polarity, a great variety of polar and nonpolar compounds are soluble in DCM in concentrations required for the synthesis. On the other hand, it has been well documented that DCM is not stable and is subjected to radical chain reactions under the action of UV light in the presence or in the absence of photosensitizers, oxygen, or water . The radical chain reactions of DCM and other chlorinated hydrocarbons have been described not only for atmospheric transformations (see Spence et al and references therein) but also for the bulk and water solutions .…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, it has been well documented that DCM is not stable and is subjected to radical chain reactions under the action of UV light in the presence or in the absence of photosensitizers, oxygen, or water . The radical chain reactions of DCM and other chlorinated hydrocarbons have been described not only for atmospheric transformations (see Spence et al and references therein) but also for the bulk and water solutions . Independent of the medium, the major products of these reactions are various chlorinated hydrocarbons formed in propagation and termination steps, HCl, and phosgene in the presence of oxygen.…”

Section: Introductionmentioning

confidence: 99%

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Dichloromethane as solvent and reagent: a case study of photoinduced reactions in mixed phosphonium‐iodonium ylide

Левина

Klimovich

Vinogradov

et al. 2018

J of Physical Organic Chem

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Several years ago the photoinduced reaction of mixed phosphonium-iodonium ylides (1) with acetylenes (2) to give λ 5 -phosphinolines (3) and substituted furans (4) was described. This reaction is one-pot, metal-free synthesis of heterocycles 3 and 4 with the yields of 40% to 80%. The reaction proceeds only in dichloromethane (DCM) at the high ylide concentrations (>0.01 mol/L). The product analysis by 31 P NMR, electrospray ionization mass spectrometry, UVvis spectrophotometry, and the dynamic light scattering study of the self-aggregation of the ylide in DCM showed a dual role of the solvent in the photoinduced reactions of mixed phosphonium-iodonium ylide: (i) at the low ylide concentrations (<0.01 mol/L), the conjugated photoinitiation of the chain reaction in DCM results in the formation of chlorine-containing products and (ii) at the high ylide concentrations (>0.01 mol/L), the photolysis mechanism is determined by self-organization of the ylide molecules to give large stable aggregates in DCM, in which the target heterocycles are synthesized. Two important issues follow from the study. First, the annulation reaction between mixed phosphonium-iodonium ylide and acetylenes occurs only when the reactive intermediates are in close proximity to one other, and, second, DCM is not inert reagent in reactions occurring with participation of radicals and in one form or another can participate in photoinduced radical reactions of various solutes.KEYWORDS annulation with acetylenes, dichloromethane, phosphonium-iodonium ylides, radical reactions, selfassembly This article is dedicated with respect and affection to the memory of the late Prof. Nikolay S. Zefirov.

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Photochemical reactivity of two gold(I) dinuclear complexes, cis/trans-(AupNBT)2dppee: Isomerization for the cis-(AupNBT)2dppee isomer, radical substitution for trans-(AupNBT)2dppee

Foley

Herring

et al. 2012

Inorganica Chimica Acta

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Photosensitivity of methylene chloride, stimulated by free radicals

Cited by 5 publications

References 6 publications

The Photophysics of Dibenzo[a,j]phenazine

The Photophysics of Dibenzo[a,j]phenazine

Dichloromethane as solvent and reagent: a case study of photoinduced reactions in mixed phosphonium‐iodonium ylide

Photochemical reactivity of two gold(I) dinuclear complexes, cis/trans-(AupNBT)2dppee: Isomerization for the cis-(AupNBT)2dppee isomer, radical substitution for trans-(AupNBT)2dppee

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