Nonlinear laser UV photochemistry of maleic acid in aqueous solution

Khoroshilova, E. V.; Kuzmina, Natalia; Letokhov, V. S.; Matveetz, Yu. A.

doi:10.1007/bf00688835

Cited by 14 publications

(4 citation statements)

References 10 publications

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“…The addition of the amino group towards the fl-position at the carbonyl group is characteristic mainly of direct ammonia addition reactions, for example, in thermal reactions. 5 Thus when the molecules of ammonium salts of o:,fl-unsaturated acids are excited to higher singlet electronic states, direct interaction of the molecular C---C bond with ammonia, probably through a unimolecular reaction without formation of intermediate products is possible. The mechanism of this reaction may consist of the intramolecular rearrangement of the system of the conjunctive bonds in the strongly excited molecule.…”

Section: Resultsmentioning

confidence: 99%

Alanine Formation in Aqueous Solution of Ammonium Acrylate Induced by UV Picosecond LaserPulses

1987

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Formation of amino acids (α- and β-alanine) and oligomers containing NH2-groups, have been discovered under the irradiation of aqueous solution of ammonium acrylate by picosecond laser pulses with intensity up to 1 GW/cm2, λ = 266 nm.The composition of photoproducts was shown to depend on intensity of laser pulses. The laser intensity dependence of the β-alanine quantum yield was of a nonlinear character. The β-alanine formation occurred under the excitation of highly singlet electronic states of ammonium acrylate molecule by two quanta of UV or one quantum of VUV light. The unimolecular mechanism of amino acid formation in such a reaction was suggested.

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Section: Resultsmentioning

confidence: 99%

Alanine Formation in Aqueous Solution of Ammonium Acrylate Induced by UV Picosecond LaserPulses

1987

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“…With a pulsed nanosecond Nd:YAG laser, however, it is improbable that S m could be populated directly from S 1 , as the lifetime of the latter is short. A second photon absorption would be more favorable for the photon fluxes provided by an ultrafast laser source 6a. As discussed above, S m could be accessed by ISC′ from T n , but this pathway should be quenched by isoprene.…”

Section: Methodsmentioning

confidence: 99%

Product Selection through Photon Flux: Laser‐Specific Lactone Synthesis

et al. 2008

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In ground-state chemistry, such as metal-catalyzed processes, exquisite levels of reaction control can often be achieved by subtle changes to the catalyst or reaction conditions. In photochemistry the situation is much more complex, as fates of excited states are governed by competing pathways for reaction, coupling to other electronic states, possible further photoexcitation, and relaxation to the ground state; thus, the outcomes of such processes are difficult to control once initiated. Some useful selectivity through singlet or triplet states can be achieved by a number of means, including use of triplet quenchers or sensitizers, [1][2][3] irradiation at user-selected wavelengths, [4] through higher exited states from multiphoton absorption, [5, 6] and feedback-based optical control using evolutionary algorithms and pulse shapers. [7] Herein, we describe how photon flux [8] can be used to switch cleanly between Norrish type I and type II pathways [1, 5, 6f-l,9] in the photochemical rearrangement of 1,3-indandiones.[10] In particular, the study demonstrates that photon flux, not average power or wavelength, is the controlling factor in product selection.As part of an ongoing study of the [5+2] photocycloaddition of maleimides, [11,12] we investigated the photochemistry of 2-ethyl-1,3-indandione 1 (Scheme 1). Unfocused [13] Nd:YAG laser irradiation of 1 at 266 nm [14] gave rise to the volatile g-alkylidinephthalide lactones 2 as an E/Z mixture (18 %). Using the higher power output of the laser at 355 nm (350 mW), a yield of 60 % of isolated 2 was obtained after 18 h. Addition of isoprene as a triplet quencher had no effect, suggesting a singlet mechanism. Quantum-yield (F) measurements using tunable lasers at five specific wavelengths between 222 and 355 nm indicated an inefficient photochemical reaction (F = 0.5-3.3 %).At this point we attempted to scale up the formation of 2 by irradiating 1 with higher (average) power UV lamps. To our surprise, however, irradiation of 1 with a low-pressure phosphor-coated mercury lamp (312 nm) gave only the diones 3 and 4 (43 %, 2:1). Similar results were obtained using medium-pressure lamps (125-600 W). Irradiation of 1 in CD 3 CN and direct analysis of the photosylate by 1 H NMR spectroscopy showed greater than 99 % of 3 and 4 and a trace of 2 (less than 1 %). These results indicate that the pathway leading to 2 is effectively closed for lamp irradiation. Significantly, addition of isoprene (one equivalent) resulted in quenching of the reaction and recovery of 1, thus indicating that 3 and 4 are formed from a different (triplet) pathway on lamp irradiation.This stark, source-dependent difference in behavior can be explained by the mechanisms in Scheme 2. Initial excitation of 1 with either source leads to the singlet state (S 1 ), from which two separate pathways can evolve. With the laser, S 1 undergoes a cleavage to the diradical 5 and subsequent recombination to the lactones 2 through a Norrish type I pathway. A singlet manifold is supported by the lack of quenchin...

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“…We have, therefore, attempted to induce efficiently the addition of the hydroxyl radicals formed by laserphotolysis of H202 to the double bond in MA, for the purpose of the selective and direct synthesis of valuable compounds such as TA containing a hydroxyl group. On the other hand, the laser-induced photochemical reaction of an aqueous solution of MA has been investigated from the viewpoint of chemistry in excited molecular electronic states relative to nonlinear laser chemistry [10,11], these studies showed that the basic process is cis-trans isomerization leading to the formation of fumaric acid (FA) with the dimerization, etc. However, there is as yet very little information on the study of the laser-induced photochemical reaction of MA for the synthesis of more valuable compounds.…”

Section: Introductionmentioning

confidence: 99%

Laser‐Induced Photochemical Reaction of Maleic Acid Solutions inthe Presence of Hydrogen Peroxide

Shimizu¹,

Sugimoto²,

Kawanishi³

et al. 1997

Laser Chemistry

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Targeting the selective and direct synthesis of tartaric acid (TA), the photochemical reactions of maleic acid (MA) solutions containing H2O2. in various solvents have been investigated using four wavelengths in the UV region between 193 and 351 nm, with high intensity from an excimer laser. All the laser irradiations in H2O resulted in the direct synthesis of TA with lower selectivity and it was found that, with XeF-laser (351 nm) irradiation in 1,4-dioxane, TA is selectively and directly synthesized from MA containing H2O2 of lower concentration at room temperature. On the other hand, none of the irradiations in methanol, N,N-dimethylformamide, acetonitrile, and tetrahydrofuran gave the selective formation of TA. On the basis of these results, the reaction scheme for the selective formation of TA is discussed.

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Nonlinear laser UV photochemistry of maleic acid in aqueous solution

Cited by 14 publications

References 10 publications

Alanine Formation in Aqueous Solution of Ammonium Acrylate Induced by UV Picosecond LaserPulses

Alanine Formation in Aqueous Solution of Ammonium Acrylate Induced by UV Picosecond LaserPulses

Product Selection through Photon Flux: Laser‐Specific Lactone Synthesis

Laser‐Induced Photochemical Reaction of Maleic Acid Solutions inthe Presence of Hydrogen Peroxide

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