Quim. New 2014 , 37 (3) , 545-548
Glycerol as solvent green obtain efficient beta-hydroxy esters
Simone de Sousa Santos Oliveira I ; Sorele Baptist Fiaux I ; Igor Ramon Barreto Lomba I ; Estela Maris Freitas Muri I ; Maria da Conceição Klaus V. Ramos II ; Francisco Radler de Aquino Neto II ; Luiza Rosaria Sousa Dias I *
I School of Pharmacy, Federal Fluminense University, Mario Viana Street, 523, Santa Rosa, 24241-000 Niterói - RJ, Brazil II Institute of Chemistry, Federal University of Rio de Janeiro, Technology Center, Block A, University City, 21949- 909 Rio de Janeiro - RJ, Brazil
* e-mail: ldias@vm.uff.br
http://dx.doi.org/10.5935/0100-4042.20140088
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422014000300026&lng=en&nrm=iso&tlng=enIn this work, we report a new method for Obtaining racemic β -hydroxyesters by reduction of β -ketoesters. The use of glycerol as a reactional medium in selective reduction of β -ketoesters into the Corresponding alcohols was shown to be a viable and more efficient alternative Compared with the conventional methodology, taking into account green chemistry prerogatives.
Keywords: β -ketoesters; β -hydroxyesters; glycerol.
Accordingly, presented here is a synthesis methodology β -hidroxiésteres by chemical reduction of β -cetoésteres with NaBH 4 ( above) using glycerol as Solvent Green compared to conventional methodology using methanol.
Compounds β -hidroxiésteres (RC (OH) CH 2 CO 2 R ') are important building blocks of other organic molecules,1-5 being the reduction of keto carbonyl β -cetoésteres one of the main ways of obtaining these compounds.Among the synthetic procedures which may be used to reduce the carbonyl grouping, often metal hydrides are used. Of these, especially borohydrides are indicated due to the low cost, simplicity of use, and is generally used as a means for reducing an organic solvent of medium polarity such as methanol. 6-10
Sodium borohydride (NaBH 4 ) is used as reagent, reaction selectivity due to the keto carbonyl. 11-12 However, the selectivity of this reagent in ketoesters compounds appears to be dependent on the reaction conditions, with the possibility of reducing the carbonyl and the carboxyl when using methanol as reaction medium.
Research in Green Chemistry has expanded the search for processes that contribute to the sustainability of the environment. This concept, introduced in the US in the 90s, proposes new approaches to the synthesis, processing and application of chemicals in order to prevent or reduce pollution caused by these activities.
The use of glycerol as a solvent in syntheses falls within the Green Chemistry concept and has attracted the attention of researchers. This alcohol triidroxilado has good compatibility with organic compounds, high boiling point, low volatility, and therefore environmental friendly. It resembles other polar organic solvents (DMF and DMSO) for their ability to dissolve organic compounds that are poorly water-miscible and facilitate the dissolution of inorganic salts. glycerol characteristics provide the use as Solvent Green in chemical synthesis reactions, given at least three principles of the Green Chemistry concept:. safer chemical synthesis, solvent insurance, and use of renewable raw materials
ethyl 3-oxobutanoate
ethyl 3-oxobutanoate
Obtaining the compounds β -hidroxiésteres (1st to 8th) Method A: the reaction mixture of β corresponding -cetoéster (7.92 mM), NaBH 4 (7.92 mM) and methanol (10 mL) maintained in an ice bath at a temperature of 0 ° C and under constant magnetic stirring. Method B: Reaction mixture of β corresponding -cetoéster (7.92 mM), NaBH 4 (7.92 mM) and glycerol (10 ml), kept at room temperature and under constant magnetic stirring. In both methods, the end of the reaction was monitored by TLC and after acidification of the medium with hydrochloric acid solution (10% v / v), the reaction is carried out isolation. The reaction can be performed by isolation extraction with organic solvents immiscible in the reaction medium such as dichloromethane or ethyl acetate (4 x 20 ml), the ethyl acetate less aggressive to the environment and more suited to the principles of green chemistry. 29 Phase The organic layer was washed with saturated NaCl solution and then dried over MgSO 4 anhydrous, filtered and the solvent evaporated initially on rotary evaporator and then in high vacuum system with variable pressure. Th data of the corresponding B-ketoester compound. Ethyl 3-hydroxybutanoate (1a). 30 Colorless liquid. IR (KBr, cm -1 ): 3440 (C-OH), 1730 (C = O). NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 1.22 [3H, C H 3 -CH-OH]; 1.26 [3H, O-CH 2 -C H 3 ]; 2.44 [2H, CHOH-C H 2 -C = O]; 4.14 to 4.21 [3H, CH 3 C H OH, OC H 2 -CH 3 ]. GC (RT): 3.8 and 3.9; 3.6 th.
Ethyl 3-hydroxybutanoate
3-hydroxypentanoate acetate (2a). 30 colorless oily liquid. IR (KBr, cm -1 ): 3443 (C-OH), 1732 (C = O).NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 0.94 [3H, C H 3 -CH 2 -CH-OH]; 1.25 [3H, O-CH 2 -C H 3 ]; 1.50 [2H, CH 3 -C H 2 -CH-OH]; 2.43 [2H, C H 2 -C = O]; 3.91 [1H, CH 3 -CH 2 -C H -OH]; 4.15 [2H, OC H 2 -CH 3 ].GC (Rt): 12.6 and 12.8; 12.3 th. 3-methyl hydroxypentanoate (3a) . 30 colorless oily liquid. IR (KBr, cm -1 ): 3450 (C-OH), 1645 (C = O).NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 0.96 [3H, C H 3 -CH 2 -CH-OH]; 1.58 [2H, CH 3 -C H 2 -CH-OH];2.48 [2H, C H 2 -C = O]; 3.71 [3 H, OC H 3 ]; 3.94 [1H, CH 3 -CH 2 -C H -OH]. GC (Rt): 10.8 and 11.2; 10.5 th. 3-hydroxyhexanoate acetate (4a) . 30 colorless oily liquid. IR (KBr, cm -1 ): 3433 (C-OH), 1732 (C = O).NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 0.90 [3H, C H 3 (CH 2 ) 2 CH-OH]; 1.22 [3H, O-CH 2 C H 3 ]; 1.54 [2H, CH 3 -C H 2 -CH 2 -CH-OH]; 1.71 [2H, CH 3 -CH 2 -C H 2 -CH-OH]; 2.50 [2H, C H 2 -C = O]; 3.90 [1H, CH 3(CH 2 ) 2 -C H -OH]; 4.15 [2H, OC H 2 - CH 3 ]. CG (tr): 16.2 and 16.6. 4-chloro-3-hydroxybutanoate Methyl (5a). 30 colorless oily liquid. IR (KBr, cm -1 ): 3415 (C-OH), 1732 (C = O). NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 2.63 [2H, C H 2 -C = O]; 3.59 [2H, Cl-C H 2 -CH-OH]; 3.71 [3 H, OC H 3 ]; 4.25 [1H, Cl-CH 2 -C H -OH]. CG (tr): 10.7 and 10.9; 9.7 a . 4,4,4-trichloro-3-hydroxybutanoate acetate (6a). 30 yellowish oily liquid. IR (KBr, cm -1 ): 3430 (C-OH), 1731 (C = O). NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 2.63 [2H, C H 2 -C = O]; 3.59 [2H, Cl-C H 2 -CH-OH]; 3.71 [3 H, OC H 3 ]; 4.25 [1H, Cl-CH 2 -C H -OH]. GC (Rt): 16.3 and 16.4; 10.9 at . 4,4,4-trifluoro-3-hydroxybutanoate acetate (7a). 30 yellowish oily liquid. IR (KBr, cm -1 ): 3430 (C-OH), 1725 (C = O). NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 1.30 [3H, O-CH 2 -C H 3 ]; 2.70 [2 H, CF 3 -CHOH-CH 2 -C = O]; 3.77 [2H, OC H 2 CH 3 ]; 4.22 [1H, CF 3 -C H -OH]. CG (tr): 2.1 and 2.2; 1.8 a . 3- (4-chlorophenyl) -3-hydroxypropanoate Methyl (8a). 30 White solid. IR (KBr, cm -1 ): 3450 (C-OH), 1732 (C = O). NMR 1 H (500 MHz) CDCl 3 / TMS ( δ ppm): 2.71 [2H, C H 2 -C = O]; 3.73 [3 H, OC H 3 ]; 5.11 [1H, CH OH]; 7.33 [4H, p -Cl C 6 H 4 -CH-OH]. GC (Rt): 23.5 and 23.7; 4.3 to .
School of Pharmacy, Federal Fluminense University, Mario Viana Street
Universidade Federal Fluminense (UFF) BELOW
BRAZIL
Institute of Chemistry, Federal University of Rio de Janeiro,
Universidade Federal do Rio de Janeiro (UFRJ) BELOW
Building in which the College of Medicine operated until 1973, ...
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P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.
P.S. : The views expressed are my personal and in no-way suggest the views of the professional body or the company that I represent.
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