Photoinduced Decarboxylation Research Articles

Photolysis of flucythrinate

Photolysis of flucythrinate ((RS)-α-cyano-3-phenoxybenzyl (S)-2-(4-difluoromethoxyphenyl)-3-methylbutyrate) in solution (methanol) by UV light (> 290 nm) and as a thin film on glass by exposure to sunlight yields products resulting from ester cleavage. The major product in solution is formed via photo-induced decarboxylation. When thin films are exposed to sunlight, flucythrinate has a half life of 8 days on glass and 3 days on a leaf surface.

ChemInform Abstract: Molecular Orbital and Experimental Studies on the Photoinduced Decarboxylation of Pyrethroid Model Esters.

AbstractThe effect of substituents on the extent of decarboxylation of (I), their m‐isomers, and (V) under irradiation is shown to decrease for (Ia) and (Va) in the order shown and to increase for (Vb) and the m‐phenoxy analogue of (I).

Molecular orbital and experimental studies on the photoinduced decarboxylation of pyrethroid model esters

A series of pyrethroid model esters with various substituents in the acid or alcohol moiety have been irradiated by u.v.-radiation (λ > 220 nm). The main reaction is decarboxylation, as evidenced by gas chromatographic (g.c.) and mass spectrometric (m.s.) analyses. In the photoinduced decarboxylation reaction, the substituent effect on the main transition, which occurs via carbonyl excitation, and on the reactivity of a radical intermediate have been examined by semiempirical molecular-orbital calculations (MNDO and CNDO/S). It has been found that the change of benzyl carbon–oxygen bond strength in the excited states is one of the important factors in determining the yield of the decarboxylated product.

Decarboxylierung cyclischer und acyclischer dicarboxylato-komplexe des platins

Abstract The interaction of (Ph3P)2PtO2 (I) with the dicarboxylic acids HO2C(CH2)nCO2H (n = 1–3), phthalic acid and maleic acid gives the dicarboxylato complexes (Ph3P)2 PtO(O)C(CH 2 ) n C(O)O (II) (n = 1–3), (Ph3P)2 PtO(O)CC 6 H 4 C(O)O (III) and cis-[(Ph3P)2Pt(O(O)CCHCHC(O)OH)2] (IV) in nearly quantitative yield. Thermal and photoinduced decarboxylation of III and IV yields the platina heterocycles (Ph3P)2 PtC 6 H 4 C(O)O (V) and (Ph3P)2 PtCHCHC(O)O (VI) with a carbon-platinum σ-bond. Complex VI has been characterized by an X-ray crystal structure determination.

Photodegradation kinetics of methyl salicylate in poly(methyl methacrylate)

AbstractIt has been found that methyl salicylate (MS) undergoes a photoinduced decarboxylation to form phenol with a quantum yield of ca. 8 × 10−5. The reaction is first order and the rate constant is proportional to the irradiance used. An activation energy of 1.2 kcal/mol was determined. Computer simulations were used to predict whether sufficient UV screening would be provided by MS‐containing PMMA lenses over the projected lifetime of solar photovoltaic devices. An effective screening lifetime of less than 2 years is predicted.

The role of electron transfer processes in the photoinduced decarboxylation of alkyl pyruvates

Irradiation of degassed solutions of alkyl pyruvates leads to the production of carbon dioxide, the yield of which is enhanced by the presence of electron acceptors, and in the case of methylviologen, the formation of reduced methylviologen is observed. A mechanism involving an electron transfer process is proposed in order to account for the decarboxylation reaction. The effect of added aromatic hydrocarbons, which act as triplet quenchers, upon the decarboxylation of methyl pyruvate is reported and was found to give enhanced carbon dioxide yields. The fact that the quenchers can enhance or ‘sensitise’ carbon dioxide production from methyl pyruvate is explained on the basis of an electron transfer mechanism.

The role of electron transfer processes in the photoinduced decarboxylation reaction of α-oxo-carboxylic acids

Irradiation of pyruvic acid in the presence of electron acceptors gives rise to enhanced carbon dioxide production, and in the case of methylviologen, this leads to the formation of reduced methylviologen, which provides further evidence that the photodecarboxylation of pyruvic acid proceeds via an electron transfer process. The addition of pyridine to benzene solutions of pyruvic acid enhances decarboxylation. The effect of added triplet quenchers on the decarboxylation of a variety of α-oxo-carboxylic acids is reported. In some cases this led to enhanced carbon dioxide yields, e.g. this occurs on the addition of various aromatic hydrocarbons to benzene solutions of pyruvic acid. The fact that the quenchers can enhance or ‘sensitise’ carbon dioxide production from α-oxo-carboxylic acids is explained on the basis of an electron transfer mechanism.

The mechanism of the photo-induced decarboxylatton of pyruvic acid in solution

It is proposed that photo-induced decarboxylation of pyruvic acid occurs via electron transfer from an excited to a ground-state molecule. Quantum yields of triplet production at 295 K in deoxygenated benzene, acetonitrile and water are 0.65, 0.88 and 0.22. The triplet state of naphthalene is quenched by pyruvic acid and it is suggested that this occurs via electron transfer.

Photo-induced decarboxylation of aliphatic acids and esters in solution. Dependence upon state of protonation of the carboxyl group

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhoto-induced decarboxylation of aliphatic acids and esters in solution. Dependence upon state of protonation of the carboxyl groupLalitha J. Mittal, J. P. Mittal, and E. HayonCite this: J. Phys. Chem. 1973, 77, 12, 1482–1487Publication Date (Print):June 1, 1973Publication History Published online1 May 2002Published inissue 1 June 1973https://doi.org/10.1021/j100631a003RIGHTS & PERMISSIONSArticle Views498Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (698 KB) Get e-Alerts

Mechanism of the photoinduced decarboxylation of carboxylic acids sensitised by aromatic ketones and quinones

The rate constants for the decarboxylation of several acids of the type RXCH2CO2H (X = O, S, and NH), sensitised by benzophenone and tetrachloro-p-benzoquinone have been determined. The reactions are considered as occurring via exciplex formation between the carbonyl compound and the acid, and in agreement with this hypothesis, the published values of rate constants for the reaction of triplet benzophenone with substituted hydrocarbons (RXCH3) are very similar to those determined for reaction with the corresponding carboxylic acid. In addition, the rate constants for decarboxylation are in the order expected from a consideration of the ionisation potentials of their corresponding substituted hydrocarbon (RXCH3). The rate constants for reaction with the quinone are higher than those for the corresponding reactions with benzophenone. Decarboxylation of (phenylthio)acetic acid in acetonitrile solution is acid catalysed whereas in benzene solution, acids slightly retard the reaction. This reaction is also quenched by methyl phenyl sulphide. Attention is drawn to the fact that the inefficiency of photoreduction of benzophenone by substituted hydrocarbons (RXCH3) can stem from the hydrogen abstraction reaction being reversible, as well as being due to exciplex formation.

Mechanism of the benzophenone photosensitised decarboxylation of carboxylic acids

Kinetic measurements of the naphthalene quenching of the photoinduced decarboxylation of acids (RXCH2·CO2H, X = O, S, NH) sensitised by benzophenone show that the decarboxylation reactions involve an exciplex intermediate.

The photoinduced decarboxylation of N-(2-chlorophenyl)glycine and (phenylthio)acetic acid sensitised by aromatic nitro-compounds

Aromatic nitro-compounds photosensitise the decarboxylation of N-(2-chlorophenyl)glycine to give 2-chloroaniline, and of (phenylthio)acetic to give thiophenol and methyl phenyl sulphide; excited charge-transfer complexes are suggested as intermediates.