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Eco‐friendly methodologies for the synthesis of some aromatic esters, well‐known cosmetic ingredients
Author(s) -
Villa C.,
Baldassari S.,
Gambaro R.,
Mariani E.,
Loupy A.
Publication year - 2005
Publication title -
international journal of cosmetic science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 62
eISSN - 1468-2494
pISSN - 0142-5463
DOI - 10.1111/j.1467-2494.2004.00246.x
Subject(s) - chemistry , benzoic acid , catalysis , organic chemistry , reagent , solvent , alkylation , combinatorial chemistry
Synopsis Solid–liquid solvent‐free phase transfer catalysis (PTC) and acidic catalysis in dry media were applied, with noticeable improvement and simplification over classical procedures in a Green Chemistry context, to the synthesis of some aromatic esters useful as cosmetic ingredients: 3‐methylbutyl 4‐methoxycinnamate, 2‐ethylhexyl 4‐methoxycinnamate, 2‐ethylhexyl 4‐(dimethylamino)benzoate and 2‐ethylhexyl salicylate, well‐known ultraviolet B sunscreen filters; 4‐isopropylbenzyl salicylate, UV absorber and cutaneous antilipoperoxidant; propyl 4‐hydroxybenzoate and butyl 4‐hydroxybenzoate (parabens), antimicrobial agents. The reactions were performed under microwave (MW) activation and conventional heating. The best results for the synthesis of cinnamic, salicylic and 4‐(dimethylamino)benzoic esters were achieved by in situ preformed carboxylates alkylation with alkyl bromides using PTC. The 4‐hydroxybenzoates were obtained in good yields by classical esterification of the acid with alcohols using a simple heterogeneous mixture of reagents with catalytic amounts of p ‐toluenesulfonic acid (PTSA). The comparisons of yields and thermal profiles under either MW or conventional heating were studied and reported.