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Reflectance imaging spectroscopy (RIS) in the visible and near infrared is revolutionizing the way cultural heritage investigators may analyze paintings nondestructively. In an ongoing, highly coll...

The introduction of carbonyl functionality using carbonylation in its various forms represents some of the largest volume and most successful applications of homogeneous catalysis in the chemical industry. These reactions have a diversity of mechanisms which, once understood, allow the manipulation of the catalytic processes in unique ways and offers options for interesting reactor designs. This review will focus on the generation of acetates and propionates, two of the simplest entities that can be generated by carbonylation, and discuss how mechanistic knowledge can be used to develop new catalysts and new reactor configurations in carbonylation processes when desired. Examples will include the development of (i) a Rh–MeI–Li catalyzed carbonylation of methyl acetate to acetic anhydride, (ii) a Mo catalyzed carbonylation of ethylene to propionic acid and propionic anhydride, (iii) a molecular Ir–La catalyst supported on carbon for heterogeneous carbonylation of methanol, (iv) alternative reactor designs ...

The introduction of carbonyl functionality using carbonylation in its various forms represents some of the largest volume and most successful applications of homogeneous catalysis in the chemical industry. These reactions have a diversity of mechanisms which, once understood, allow the manipulation of the catalytic processes in unique ways and offers options for interesting reactor designs. This review will focus on the generation of acetates and propionates, two of the simplest entities that can be generated by carbonylation, and discuss how mechanistic knowledge can be used to develop new catalysts and new reactor configurations in carbonylation processes when desired. Examples will include the development of (i) a Rh–MeI–Li catalyzed carbonylation of methyl acetate to acetic anhydride, (ii) a Mo catalyzed carbonylation of ethylene to propionic acid and propionic anhydride, (iii) a molecular Ir–La catalyst supported on carbon for heterogeneous carbonylation of methanol, (iv) alternative reactor designs ...

We have examined the reduction of α-diketones and α-keto esters in HI-acetic anhydride mixtures and found that the reaction gives good-to-excellent yields of α-acetoxy ketones and esters

The synthesis, characterization, and reactivity of the triphenylmethylphosphonium salts of several anionic ruthenium iodo carbonyl complexes are described. These complexes included the facial and meridional isomers of (Ru(CO)/sub 3/I/sub 3/)/sup -/, and the dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/sup 2 -/. The two (Ru(CO)/sub 3/I/sub 3/)/sup -/ isomers were characterized by their infrared spectra and by the /sup 13/C NMR spectra of /sup 13/CO-enriched samples of these compounds. The dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/sup 2 -/, which was generated by heating the facial isomer under Ar, was characterized by X-ray crystallography and was found to have S/sub 2/ symmetry. (Ph/sub 3/PMe)/sub 2/(Ru/sub 2/(CO)/sub 4/I/sub 6/) crystallizes in the triclinic space group P1-C/sub i//sup 1/ (No. 2) with a = 9.794 (4) A, b = 11.158 (4) A, c = 11.710 (5) A, ..cap alpha.. = 85.01 (3)/sup 0/, ..beta.. = 93.70 (3)/sup 0/, ..gamma.. = 93.70 (3)/sup 0/ and Z = 1. The meridional isomer of (Ru(CO)/sub 3/I/sub 3/)/sup -/ was generated by adding carbon monoxide to the dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/sup 2 -/ at atmospheric pressure. The meridional isomer of (Ru(CO)/sub 3/I/sub 3/)/sup -/ could be used to regenerate the dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/supmore » 2 -/ by heating the complex under Ar in the presence of excess iodide, or it could be used to regenerate the facial isomer by heating the complex under a carbon monoxide atmosphere.« less

The homologation of methyl esters with synthesis gas in the presence of iodine-promoted ruthenium catalysts has been examined. This investigation, which uses a gas-purged liquid-sampling autoclave, shows that there are four major reactions occurring simultaneously. These are homologation of the methyl ester to form an ethyl ester, carbonylation of the methyl ester to generate acetic acid, reduction of the acyl moiety, and hydrogenolysis of the methyl ester to yield methane. When LiI was used as the iodine promoter at an I/Ru ratio of 15/1, the predominant pathways was homologation. When methyl iodide was used as the promoter in place of LiI, a selectivity change resulted. The predominant pathway with methyl iodide was acyl reduction. The relative contribution of each pathway was affected by the partial pressures of carbon monoxide and hydrogen, and by the level of iodine present. A deuterium-labeling experiment was also performed and established the integrity of the processes described above and excluded the hydrogenation of carbon monoxide to methanol as a potential pathway to products.

6-Substituted 2-acetonaphthones can be generated from para substituted benzaldehydes and acetylacetone (2,4-pentanedione) in three reactions consisting of condensing the benzaldehyde with acetylacetone, acetalizing the resultant 3-benzylidene 2,4-pentanedione (α-acetyl benzalacetones), with trimethyl orthoformate, pyrolyzing the acetal either in the vapor phase at 475°C or by heating in a high boiling solvent, such as 1-methylnaphthalene.

Liquid sampling procedures for high-pressure reactions indicate that the ruthenium-catalyzed homologation of acetic acid proceeds through a series of consecutive reactions. The process is characterized by an initial rapid generation of ethanol and ethyl acetate (obtained via hydrogenation and subsequent esterification) followed by the subsequent generation of propionic acid (obtained via carbonylation). Higher ester and acid homologs were also subsequently detected. A gas chromatographic-mass spectroscopic (GC-MS) examination of the product mixture revealed the presence of a homologous series of alkyl iodides which are possible intermediates in the carbonylation of esters to acids. These results and observations by previous workers are explained in the context of other work on ruthenium-catalyzed homologations of organic oxygenates.

Les amines et les sulfures de β-malonyl allyle se cyclisent en presence de tetrachloropalladate de lithium et d'une base pour donner des palladocycles bicycliques qui conduisent aux cyclopentanes par hydrogenation. On peut ainsi preparer une serie de cetones cycliques

6-Substituted 2-acetonaphthones can be generated from para substituted benzaldehydes and acetylacetone (2,4-pentanedione) in three reactions consisting of condensing the benzaldehyde with acetylacetone, acetalizing the resultant 3-benzylidene 2,4-pentanedione (α-acetyl benzalacetones), with trimethyl orthoformate, pyrolyzing the acetal either in the vapor phase at 475°C or by heating in a high boiling solvent, such as 1-methylnaphthalene.

The synthesis, characterization, and reactivity of the triphenylmethylphosphonium salts of several anionic ruthenium iodo carbonyl complexes are described. These complexes included the facial and meridional isomers of (Ru(CO)/sub 3/I/sub 3/)/sup -/, and the dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/sup 2 -/. The two (Ru(CO)/sub 3/I/sub 3/)/sup -/ isomers were characterized by their infrared spectra and by the /sup 13/C NMR spectra of /sup 13/CO-enriched samples of these compounds. The dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/sup 2 -/, which was generated by heating the facial isomer under Ar, was characterized by X-ray crystallography and was found to have S/sub 2/ symmetry. (Ph/sub 3/PMe)/sub 2/(Ru/sub 2/(CO)/sub 4/I/sub 6/) crystallizes in the triclinic space group P1-C/sub i//sup 1/ (No. 2) with a = 9.794 (4) A, b = 11.158 (4) A, c = 11.710 (5) A, ..cap alpha.. = 85.01 (3)/sup 0/, ..beta.. = 93.70 (3)/sup 0/, ..gamma.. = 93.70 (3)/sup 0/ and Z = 1. The meridional isomer of (Ru(CO)/sub 3/I/sub 3/)/sup -/ was generated by adding carbon monoxide to the dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/sup 2 -/ at atmospheric pressure. The meridional isomer of (Ru(CO)/sub 3/I/sub 3/)/sup -/ could be used to regenerate the dimeric dianion (Ru/sub 2/(CO)/sub 4/I/sub 6/)/supmore » 2 -/ by heating the complex under Ar in the presence of excess iodide, or it could be used to regenerate the facial isomer by heating the complex under a carbon monoxide atmosphere.« less