Evaluation of the synthesis of 1-(pentafluorophenyl)-4,5-dihydro-1H-pyrazoles using green metrics

1-(Pentafluorophenyl)-4,5-dihydro-1 H -pyrazoles were synthesized from the cyclocondensation reactions of 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (CX 3 C(O)CH=C(R 1 )OR, where X = F, Cl; R = Me, Et; R 1  = H, Me, Et, n -Pr, i -Pr, n -Bu, i -Pent, Ph, 4-Cl-C 6 H 4 , 4-Br-C 6 H 4 , 4-F-C 6 H 4 ) with pe...

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Bibliographic Details
Published in:Monatshefte für Chemie 2013-07, Vol.144 (7), p.1043-1050
Main Authors: Martins, Marcos A. P., Beck, Paulo H., Buriol, Lilian, Frizzo, Clarissa P., Moreira, Dayse N., Marzari, Mara R. B., Zanatta, Marcileia, Machado, Pablo, Zanatta, Nilo, Bonacorso, Helio G.
Format: Article
Language:English
Subjects:
Analytical Chemistry
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Inorganic Chemistry
Organic Chemistry
Original Paper
Physical Chemistry
Theoretical and Computational Chemistry
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Summary:1-(Pentafluorophenyl)-4,5-dihydro-1 H -pyrazoles were synthesized from the cyclocondensation reactions of 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (CX 3 C(O)CH=C(R 1 )OR, where X = F, Cl; R = Me, Et; R 1  = H, Me, Et, n -Pr, i -Pr, n -Bu, i -Pent, Ph, 4-Cl-C 6 H 4 , 4-Br-C 6 H 4 , 4-F-C 6 H 4 ) with pentafluorophenyl hydrazine. Pyrazoles were obtained under microwave irradiation in solvent-free conditions or under conventional heating in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF 4 ]. These procedures furnished products in moderate to good yields in a short reaction time. Atom economy, reaction mass efficiency (RME), and environmental factor (E-factor) were determined for the cyclocondensation reaction performed under microwave (MW)/solvent-free and under conventional thermal heating/[BMIM][BF 4 ] conditions. RME and E-factor indicated that the solvent-free procedure is invariably less green than [BMIM][BF 4 ] when the isolated product was considered. Graphical abstract
ISSN:0026-9247
1434-4475
DOI:10.1007/s00706-013-0930-x