With the aim of determining the formation of R-dicarbonyl intermediates during beer aging on the shelf, R-dicarbonyls were identified and quantified after derivatization with 1,2-diaminobenze to generate quinoxalines. The sensory effects of R-dicarbonyls were evaluated by the quantification of key Strecker aldehydes and by GC-olfactometry (GCO)analysis of beer headspace using solid phase microextraction. Four R-dicarbonyls, reported here for the first time, were detected in fresh and aged beers, three were derived from the 2,3-enolization pathway of mono-and disaccharides, and the fourth was derived from the epimerization of 3-deoxy-2-hexosulose. Ten R-dicarbonyls were quantified during beer processing and during different periods of beer aging at 28°C. The aging periods were from 15 to 105 days. During beer aging, 1-deoxydiuloses were produced and degraded, while 1,4-dideoxydiuloses were produced at the highest rates. The GCO analysis indicated that forced beer aging increased the amounts of furaneol, trans-2-nonenal, and phenylacetaldehyde. The blockage of R-dicarbonyls inhibited the accumulation of sensory-active aldehydes in the beer headspace.

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This report explores the photocatalytic activity of TiO 2 , Ti(IV) citrate and Zn(II) tetraphenyl porphyrin (ZnTPP) and its mixtures in water/oil (W/O) and O/W microemulsion (lE). The 4-chlorophenol was used to assess the efficiency of the photoactive compounds in a degradation process. A simple photoelectrochemical study based on cyclic voltammetry was also developed. The results revealed that most of the photocatalytic procedures developed are effective in the degradation process. However, phenol was the major product obtained.

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The reaction of 2,3-acetylenic acids (1a-d) with thionyl chloride in DMF under mild conditions gave E,Z-3-chloro-2-alkenoic acids (2a-d) or esters (3a-d) depending on treating the reaction mixture with either water or alcohols.3-Halo-2-alkenoic acids [1] and their esters [2][3][4] are valuable and versatile intermediates in organic synthesis due to their high functionality (halogen atom, carbon-carbon double bond and a carboxylic or ester group). Preparation methods for these intermediates are based in the addition of hydrogen halides [5][6][7][8][9] and halides salts of lithium [10][11][12] or sodium [13,14] in acetic acid to a 2,3 acetylenic acid or ester.During the preparation of some ester analogs of 3-phenyl-2-propynoic acid using thionyl chloride in dimethylformamide and the corresponding SYNTHETIC COMMUNICATIONS

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