Sulfuric acid on silica-gel: an inexpensive catalyst for aromatic nitration

Riego, J.; Sedin, Zeno; Zaldivar, J. M.; Marziano, Nunziata Clara; Tortato, Claudio

doi:10.1016/0040-4039(95)02174-4

Cited by 178 publications

(89 citation statements)

References 14 publications

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“…The use of a catalytic amount of HPAs is key for the reaction to proceed with high regiospecificity and each of the metal nitrates used afforded o-nitrophenols as a single regioisomer in good to excellent yields. Even though the reaction proceeds with various metal nitrates, the time required for completion of the reaction was found to be less and the yields are more effective with Th(NO 3 ) 4 .5H 2 O. Phenols were treated with a metal nitrate and HPAs in acetonitrile at reflux to afford o-nitrophenol as the exclusive product in satisfactory to good yields (Scheme 1). The scope and generality of the method is illustrated with several examples in Table 3 and all of them yielded the o-nitro product exclusively in good to excellent yields.…”

Section: Resultsmentioning

confidence: 99%

“…The mixture was then washed with saturated sodium hydrogen carbonate (10 mL) and the product extracted into dichloromethane (2 × 5 mL). The combined organic extracts were washed with distilled water (10 mL), dried over anhydrous MgSO 4 Reusability of the catalyst. The catalyst was recovered after the reaction and reused as a catalyst in the nitration reactions.…”

Section: Methodsmentioning

confidence: 99%

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Heteropolyacids as an efficient and reusable catalytic system for the regiospecific nitration of phenols with metal nitrates

Baghernejad¹,

Heravi²,

Oskooie³

et al. 2012

Bull. Chem. Soc. Eth.

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ABSTRACT. Highly regiospecific mononitration of phenols and substituted phenols is accomplished employing a metal nitrate and a catalytic amount of heteropolyacid in acetonitrile. An exclusive ortho-selectivity was observed with excellent yields. A variety of metal nitrates were used to obtain o-nitrophenols exclusively in good to excellent yields. The use of heteropolyacid is key for the selectivity observed.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Heteropolyacids as an efficient and reusable catalytic system for the regiospecific nitration of phenols with metal nitrates

Baghernejad¹,

Heravi²,

Oskooie³

et al. 2012

Bull. Chem. Soc. Eth.

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“…Therefore, much effort has been made on the improvement of nitration process without strong acids [1]. Preliminarily in order to avoid the risk of sulfuric acid, sulfuric acid was supported on silica gel to apply to the aromatic nitration with nitric acid (HNO 3 ) [2]. Recently, silica gel which is the most commonly desiccant [3] has been used as a dehydration agent instead of sulfuric acid together with nitration reagents such as Bi(NO 3 ) 3 [4], HNO 3 [5], Ce(NH 4 )(NO 3 ) 5 [6], and AcONO 2 [7] in solid state.…”

Section: Introductionmentioning

confidence: 99%

Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel

Matsumoto¹,

Yamauchi²,

Ishikawa³

et al. 2017

IJOC

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Nitroaromatics are usually prepared using a mixed acid of nitric acid with strong acids. However, the use of strong acids caused dangerous work-up and the disposal of large amounts of acid-waste. Therefore, much effort has been made on the improvement of nitration process without strong acids. We examined solid-phase aromatic nitration with Mg(NO 3 ) 2 on silica gel in order to establish the nitration process without strong acids. The nitration of 1,2-and 1,3-, 1,4-dimethoxybenzenes and 4-methylanisole with Mg(NO 3 ) 2 proceeded by heating on silica gel at 150˚C for 4 -5 h to produce the nitroaromatics. The nitration of 1,3,5-trimethoxybenzene produced the nitrated dimer, 2,4,6,2', 4',6'-hexamethoxy-3-nitrobiphenyl, which was not isolated in other solid-phase nitration. In the cases of naphthalene derivatives, the α-nitrated compounds were obtained. In the cases of p-cresol and 2-naphthol, the esterification occurred at the hydroxyl group to give 4-tolyl nitrate and 2-naphthyl nitrate, respectively. It is synthetic interest to note that nitrate esters were isolated in solid phase. Thus Mg(NO 3 ) 2 -SiO 2 composite was mild reagent for solid-phase nitration. Acidity of Mg(NO 3 ) 2 -SiO 2 composite was determined to be pH 0.96 by the measurement of absorption spectra on a micro spectrophotometer using meso-tetra(p-cyanophenyl)porphyrin as a pH-indicator. Mg(NO 3 ) 2 -SiO 2 composite made acidic conditions. Therefore, it was suggested that Mg(NO 3 ) 2 reacted with proton on silica gel to form the 2 NO + . Thus, electron-rich aromatic hydrocarbons led the efficient nitration through electrophilic attack of 2 NO + . After the nitration, acidic Mg(NO 3 ) 2 -SiO 2 composite could be turned into neutrality by exposing wet conditions and disposed safely since the composite did not involve harmful elements. Thus the solid-phase nitration using Mg(NO 3 ) 2 -SiO 2 composite will provide safety and environmentally conscious chemical process.

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“…Smith and coworks have utilized zeolites to enhance the para-selectivity in chlorination, 8 acylation, 9 and methanesulfonylation 10 of simple aromatic substrates. The present investigation was to develop a mild, easy to operate and efficient catalyst [11][12][13][14] without involving sulfuric acid and some progress has been achieved. 4-and 3-Nitro-o-xylenes are used as intermediates for the production of vitamins, fragrances, agrochemicals, dyes, etc.…”

mentioning

confidence: 99%

Improved Regioselective Mononitration of o-Xylene over HBEA-500 Zeolite Catalyst

Shi¹,

Tai²,

Liu³

2013

Bulletin of the Korean Chemical Society

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Sulfuric acid on silica-gel: an inexpensive catalyst for aromatic nitration

Cited by 178 publications

References 14 publications

Heteropolyacids as an efficient and reusable catalytic system for the regiospecific nitration of phenols with metal nitrates

Heteropolyacids as an efficient and reusable catalytic system for the regiospecific nitration of phenols with metal nitrates

Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel

Improved Regioselective Mononitration of o-Xylene over HBEA-500 Zeolite Catalyst

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Sulfuric acid on silica-gel: an inexpensive catalyst for aromatic nitration

Cited by 178 publications

References 14 publications

Heteropolyacids as an efficient and reusable catalytic system for the regiospecific nitration of phenols with metal nitrates

Heteropolyacids as an efficient and reusable catalytic system for the regiospecific nitration of phenols with metal nitrates

Solid-Phase Aromatic Nitration with Mg(NO&lt;sub&gt;3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; on Silica Gel

Improved Regioselective Mononitration of o-Xylene over HBEA-500 Zeolite Catalyst

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Solid-Phase Aromatic Nitration with Mg(NO<sub>3</sub>)<sub>2</sub> on Silica Gel