We present an alternative synthetic route to acrylic acid, starting from the platform chemical lactic acid and using heterogeneous catalysis. To improve selectivity, we designed an indirect dehydration reaction that proceeds via acetoxylation of lactic acid to 2-acetoxypropionic acid. This intermediate can then be pyrolized to acrylic acid. Acetic acid is used both as a reagent and a solvent in the first step, and may be recovered in the subsequent pyrolysis step. We tested a range of solid acid catalysts for the acetoxylation step (Y zeolites, sulfated zirconia, ion-exchange resins, sulfonated graphene, and various sulfonated silica gels and mixed oxides). Recycling studies were carried out for the most active catalysts. To enable quantitative analysis using gas chromatography we also developed a reliable silylation derivatization method, which is also reported. These results open opportunities for improving the biorenewable production of acrylic acid.

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Catalytic acetoxylation of lactic acid to 2-acetoxypropionic acid, en route to acrylic acid

A CD-modified CE method was established for quantitative determination of seven hydroxy acids in cosmetic products. This method involved chemometric experimental design aspects, including fractional factorial design and central composite design. Chemometric experimental design was used to enhance the method's separation capability and to explore the interactions between parameters. Compared to the traditional investigation that uses multiple parameters, the method that used chemometric experimental design was less time-consuming and lower in cost. In this study, the influences of three experimental variables (phosphate concentration, surfactant concentration, and methanol percentage) on the experimental response were investigated by applying a chromatographic resolution statistic function. The optimized conditions were as follows: a running buffer of 150 mM phosphate solution (pH 7) containing 0.5 mM CTAB, 3 mM γ-CD, and 25% methanol; 20 s sample injection at 0.5 psi; a separation voltage of -15 kV; temperature was set at 25°C; and UV detection at 200 nm. The seven hydroxy acids were well separated in less than 10 min. The LOD (S/N = 3) was 625 nM for both salicylic acid and mandelic acid. The correlation coefficient of the regression curve was greater than 0.998. The RSD and relative error values were all less than 9.21%. After optimization and validation, this simple and rapid analysis method was considered to be established and was successfully applied to several commercial cosmetic products.

Determination of hydroxy acids in cosmetics by chemometric experimental design and cyclodextrin‐modified capillary electrophoresis

O acido glicolico e amplamente utilizado na terapeutica para se obter um peeling suave, levando ao afinamento do estrato corneo util na renovacao da epiderme e na reducao das linhas faciais. Porem, em concentracoes elevadas pode estar associado a um alto potencial de irritacao da pele. O peeling quimico tem diversas aplicacoes clinicas dentre elas o tratamento da pele facial lesada por problemas como acne, ictiose, melasma, verrugas e outros problemas. O presente trabalho objetivou estabelecer e validar a metodologia analitica para a determinacao do teor de acido glicolico na materia-prima e em formulacoes dermocosmeticas, tendo empregado o metodo titulometrico de neutralizacao acido-base, determinando-se o ponto de equivalencia com indicador e/ou indicacao potenciometrica. A analise do teor de acido glicolico na materia-prima e, particularmente, no produto acabado, e importante para o controle de qualidade, principalmente, para a seguranca dos consumidores. Portanto, a materia-prima e os produtos, contendo acido glicolico, foram analisados em dois dias, quanto ao teor de acido glicolico livre e total utilizando solucoes de hidroxido de sodio 0,1 N e o acido cloridrico 0,1 N. A metodologia desenvolvida baseou-se na reacao com a substância ativa e com as caracteristicas proprias destas formulacoes, demonstrando ser pratica e eficaz na quantificacao do acido glicolico.

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Desenvolvimento e validação de metodologia analítica para a determinação do teor de ácido glicólico na matéria-prima e em formulações dermocosméticas

In this paper some principal problems related with application of organic hydroxyacids in phytocosmetics formulations and cosmetics treatment have been described. Detailed characteristics of the human skin structure and physicochemical properties of alpha-hydroxyacids (AHA) and beta-hydroxyacids (BHA) as glycolic acid, lactic acid, citric acid, malic acid, tartaric acid and salicylic acid, have been presented. In addition some modern analytical procedures for rapid and selective determination of hydroxyacids in cosmetics as well as the basic international and domestic legal rules related with use of hydroxyacids in cosmetic procedures was discussed. The set of practical indications and contraindications linked with application of the fruit originated hydroxyacids to cosmetological intervention and treatments was also mentioned. The most important factors determining biological action efficiency of alpha-hydroxyacids (AHA) was shortly specified.

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Hydroksykwasy organiczne w fitokosmetykach rewitalizujących

aValiação de MÉtodos de MistuRa MagistRais paRa inCoRpoRação de ÁCido gliCÓliCo eM base seMi‑ sÓlida

A simple and rapid procedure is described for the isolation, silylation, and simultaneous capillary gas chromatographic quantitation of alpha hydroxy acids and beta hydroxy acids in various personal care products. The sample is dissolved in acidified N,N-dimethylformamide to simultaneously acidify/extract the hydroxy acids; a portion is then trimethylsilyl derivatized with BSTFA and quantified by capillary gas chromatography (GC) using flame ionization detection.

Molever K

Papers

Simultaneous determination of alpha and beta hydroxy acids in personal care products by capillary gas chromatography.