Obtaining ortho-nitrophenol

Objective

Regiospecific preparation of o-nitrophenol using Ni(NO3)2 and p-toluenesulfonic acid.

Obtaining ortho-nitrophenol
Obtaining ortho-nitrophenol

Background

Conventional reactions of nitration of aromatic compounds involve the use of HNO3 as the nitrating agent in the presence of H2SO4. In this experiment a nitration process that is fast and regiospecific and that has low environmen- tal impact is proposed. The reaction is performed with nickel nitrate and is catalyzed with p-toluenesulfonic acid in acetone. Under these conditions, the nitration of phenol occurs only at the orto-position with respect to the hydroxyl group. The reaction can be performed both at room temperature and at reflux, although to reflux, the reaction time is relatively short.

Experimental procedure

In a 100 ml round-bottom flask provided with a stir bar, dissolve 94 mg (1 mmol) of phenol in 15 ml of acetone. Add to the solution, 290.8 mg of Ni(NO3)2·6 H2O (1 mmol) and a catalytic amount of p-toluenesulfonic acid (5 mg). Reflux the reaction for 30 min. Remove the solvent under reduced pressure (rotary evaporator), treat the residue with 20 ml of CH2Cl2, and wash the solution with water (20 ml) in a separatory funnel. Dry the organic layer (lower) on anhydrous sodium sulfate for several minutes. Then remove the desiccant by gravity filtration, filtering in a tared round-bottom flask. Remove the solvent under reduced pressure (rotary evaporator), weigh the solid, and calculate the yield (estimated yield 85 %, m.p. = 44-45 ºC). Optionally, purify by column chromatography using hexane:ethyl acetate (98:2) as eluent.

Physico-chemical properties

This table collects data for the molecular weight (Mw), melting point (M.p.) boiling point (B.p.) and density of the reactives and compounds used in this laboratory experiment.

Name Mw (g/mol) M.p. (ºC) B.p. (ºC) Density (g/ml)
Acetone 58.08 -94 56 0.791
CH2Cl2 84.93 -97 40.0 1.33
Ethyl acetate 88.11 -84 77.1 0.902
Hexane 86.18 -95 69 0.659
Na2SO4 142.04 884 - 2.630
Ni(NO3)2·6H2O 290.79 56 136.7 2.050
Phenol 94.11 40-42 182 1.07
o-Nitrophenol 139.11 45 214 -
p-Toluenesulfonic acid monohydrate 190.22 100-106 - -

GHS pictograms

Hazard pictograms form part of the international Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and are collected in the followinf Table for the chemical compounds used in this experiment.

Name GHS
Acetone ghs02  Danger Warning Flammable pictogram ghs07  Warning Toxic cat. 4 Irritant cat. 2 or 3 Lower systemic health hazards pictogram
CH2Cl2 ghs08  Danger Warning Systemic health hazards pictogram
Ethyl acetate ghs02  Danger Warning Flammable pictogram ghs07  Warning Toxic cat. 4 Irritant cat. 2 or 3 Lower systemic health hazards pictogram
Hexane ghs02  Danger Warning Flammable pictogram ghs08  Danger Warning Systemic health hazards pictogram ghs07  Warning Toxic cat. 4 Irritant cat. 2 or 3 Lower systemic health hazards pictogram ghs09  Warning (for cat. 1) (for cat. 2 no signal word) Environmental hazard pictogram
Na2SO4 Non-hazardous
Ni(NO3)2·6H2O ghs03  Danger Warning Oxidizing pictogram ghs08  Danger Warning Systemic health hazards pictogram ghs05  Danger Warning Corrosive cat. 1 pictogram ghs09  Warning (for cat. 1) (for cat. 2 no signal word) Environmental hazard pictogram
Phenol ghs06  Danger Toxic cat. 1–3 pictogram ghs08  Danger Warning Systemic health hazards pictogram ghs05  Danger Warning Corrosive cat. 1 pictogram
o-Nitrophenol ghs07  Warning Toxic cat. 4 Irritant cat. 2 or 3 Lower systemic health hazards pictogram
p-Toluenesulfonic acid monohydrate ghs07  Warning Toxic cat. 4 Irritant cat. 2 or 3 Lower systemic health hazards pictogram ghs05  Danger Warning Corrosive cat. 1 pictogram

International Chemical Identifier

The IUPAC InChI key identifiers for the main compounds used in this experiment are provided to facilitate the nomenclature and formulation of chemical compounds and the search for information on the Internet for these compounds.

Acetone CSCPPACGZOOCGX-UHFFFAOYSA-N
CH2Cl2 YMWUJEATGCHHMB-UHFFFAOYSA-N
Ethyl acetate XEKOWRVHYACXOJ-UHFFFAOYSA-N
Hexane VLKZOEOYAKHREP-UHFFFAOYSA-N
Na2SO4 PMZURENOXWZQFD-UHFFFAOYSA-L
Ni(NO3)2·6H2O AOPCKOPZYFFEDA-UHFFFAOYSA-N
Phenol ISWSIDIOOBJBQZ-UHFFFAOYSA-N
o-Nitrophenol IQUPABOKLQSFBK-UHFFFAOYSA-N
p-Toluenesulfonic acid monohydrate KJIFKLIQANRMOU-UHFFFAOYSA-N

References

Shares