107 Citazioni (Scopus)

Abstract

The photocatalytic oxidation of different benzene derivatives has been investigated in order to understand how the substituent group affects the selectivity to hydroxylated compounds. Experimental runs were performed by using TiO2 (Merck) aqueous suspensions at natural pH irradiated by near-UV light. The organic molecules used as substrate contained an electron withdrawing group (EWG) (nitrobenzene, cyanobenzene, benzoic acid, 1-phenylethanone), an electron donor one (EDG) (phenol, phenylamine, N-phenylacetamide) or both an EWG and an EDG (4-chlorophenol). The results clearly indicated that the primary photocatalytic oxidation of aromatic compounds containing an EDG gives rise mainly to ortho and para mono-hydroxy derivatives while in the presence of an EWG all the mono-hydroxy derivatives are obtained. This finding can open a new green route for the synthesis of hydroxylated aromatic compounds. Moreover, in the presence of both an ED and an EW group, as in the case of 4-chlorophenol and hydroxy-cyanobenzenes, the attack of the hydroxyl radical takes place only in the positions activated by -OH. A competing reaction pathway to total oxidation was also observed from the starting of the irradiation; this pathway was more important for compounds containing an EWG. This evidence can be explained by considering the strong interaction of these molecules with the TiO2 surface. In fact, adsorption in the dark, measured for all the compounds, resulted to be significant only for molecules having strongly EWG's.
Lingua originaleEnglish
pagine (da-a)118-127
Numero di pagine10
RivistaCatalysis Today
Volume122
Stato di pubblicazionePublished - 2007

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Photocatalysis
Aromatic compounds
Hydroxyl Radical
Oxidation
Electrons
Derivatives
Molecules
Aniline Compounds
Benzene Derivatives
Benzoic Acid
Nitrobenzene
Benzoic acid
Aniline
Phenol
Ultraviolet radiation
Phenols
Benzene
Suspensions
Irradiation
Adsorption

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

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@article{bad8f522aa654693a074db5bb4e47b1d,
title = "Selectivity of hydroxyl radical in the partial oxidation of aromatic compounds in heterogeneous photocatalysis",
abstract = "The photocatalytic oxidation of different benzene derivatives has been investigated in order to understand how the substituent group affects the selectivity to hydroxylated compounds. Experimental runs were performed by using TiO2 (Merck) aqueous suspensions at natural pH irradiated by near-UV light. The organic molecules used as substrate contained an electron withdrawing group (EWG) (nitrobenzene, cyanobenzene, benzoic acid, 1-phenylethanone), an electron donor one (EDG) (phenol, phenylamine, N-phenylacetamide) or both an EWG and an EDG (4-chlorophenol). The results clearly indicated that the primary photocatalytic oxidation of aromatic compounds containing an EDG gives rise mainly to ortho and para mono-hydroxy derivatives while in the presence of an EWG all the mono-hydroxy derivatives are obtained. This finding can open a new green route for the synthesis of hydroxylated aromatic compounds. Moreover, in the presence of both an ED and an EW group, as in the case of 4-chlorophenol and hydroxy-cyanobenzenes, the attack of the hydroxyl radical takes place only in the positions activated by -OH. A competing reaction pathway to total oxidation was also observed from the starting of the irradiation; this pathway was more important for compounds containing an EWG. This evidence can be explained by considering the strong interaction of these molecules with the TiO2 surface. In fact, adsorption in the dark, measured for all the compounds, resulted to be significant only for molecules having strongly EWG's.",
author = "Vincenzo Augugliaro and {Di Paola}, Agatino and Giuseppe Marci' and Mario Schiavello and Leonardo Palmisano and Vittorio Loddo and {Garcia Lopez}, {Elisa Isabel} and Maurizio Addamo and Giovanni Palmisano and Tullio Caronna",
year = "2007",
language = "English",
volume = "122",
pages = "118--127",
journal = "Catalysis Today",
issn = "0920-5861",
publisher = "Elsevier",

}

TY - JOUR

T1 - Selectivity of hydroxyl radical in the partial oxidation of aromatic compounds in heterogeneous photocatalysis

AU - Augugliaro, Vincenzo

AU - Di Paola, Agatino

AU - Marci', Giuseppe

AU - Schiavello, Mario

AU - Palmisano, Leonardo

AU - Loddo, Vittorio

AU - Garcia Lopez, Elisa Isabel

AU - Addamo, Maurizio

AU - Palmisano, Giovanni

AU - Caronna, Tullio

PY - 2007

Y1 - 2007

N2 - The photocatalytic oxidation of different benzene derivatives has been investigated in order to understand how the substituent group affects the selectivity to hydroxylated compounds. Experimental runs were performed by using TiO2 (Merck) aqueous suspensions at natural pH irradiated by near-UV light. The organic molecules used as substrate contained an electron withdrawing group (EWG) (nitrobenzene, cyanobenzene, benzoic acid, 1-phenylethanone), an electron donor one (EDG) (phenol, phenylamine, N-phenylacetamide) or both an EWG and an EDG (4-chlorophenol). The results clearly indicated that the primary photocatalytic oxidation of aromatic compounds containing an EDG gives rise mainly to ortho and para mono-hydroxy derivatives while in the presence of an EWG all the mono-hydroxy derivatives are obtained. This finding can open a new green route for the synthesis of hydroxylated aromatic compounds. Moreover, in the presence of both an ED and an EW group, as in the case of 4-chlorophenol and hydroxy-cyanobenzenes, the attack of the hydroxyl radical takes place only in the positions activated by -OH. A competing reaction pathway to total oxidation was also observed from the starting of the irradiation; this pathway was more important for compounds containing an EWG. This evidence can be explained by considering the strong interaction of these molecules with the TiO2 surface. In fact, adsorption in the dark, measured for all the compounds, resulted to be significant only for molecules having strongly EWG's.

AB - The photocatalytic oxidation of different benzene derivatives has been investigated in order to understand how the substituent group affects the selectivity to hydroxylated compounds. Experimental runs were performed by using TiO2 (Merck) aqueous suspensions at natural pH irradiated by near-UV light. The organic molecules used as substrate contained an electron withdrawing group (EWG) (nitrobenzene, cyanobenzene, benzoic acid, 1-phenylethanone), an electron donor one (EDG) (phenol, phenylamine, N-phenylacetamide) or both an EWG and an EDG (4-chlorophenol). The results clearly indicated that the primary photocatalytic oxidation of aromatic compounds containing an EDG gives rise mainly to ortho and para mono-hydroxy derivatives while in the presence of an EWG all the mono-hydroxy derivatives are obtained. This finding can open a new green route for the synthesis of hydroxylated aromatic compounds. Moreover, in the presence of both an ED and an EW group, as in the case of 4-chlorophenol and hydroxy-cyanobenzenes, the attack of the hydroxyl radical takes place only in the positions activated by -OH. A competing reaction pathway to total oxidation was also observed from the starting of the irradiation; this pathway was more important for compounds containing an EWG. This evidence can be explained by considering the strong interaction of these molecules with the TiO2 surface. In fact, adsorption in the dark, measured for all the compounds, resulted to be significant only for molecules having strongly EWG's.

UR - http://hdl.handle.net/10447/1508

M3 - Article

VL - 122

SP - 118

EP - 127

JO - Catalysis Today

JF - Catalysis Today

SN - 0920-5861

ER -