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o-formylation of 4-tert-butylphenol; 5-tert-butyl-2-hydroxybenzaldehyde

SyntheticPage 643
DOI: 10.1039/SP643
Submitted Jul 22, 2013, published Jul 24, 2013
Lihong Li (Lihongli0707@yahoo.com), Pratik Gurnani (pratik.gurnani@warwick.ac.uk)
A contribution from Scott group, Warwick University


			Reaction Scheme: <IMG src="/images/empty.gif">o-formylation of <SPAN id=csm1374663463256 class="csm-chemical-name csm-not-validated" title=4-tert-butylphenol grpid="1">4-tert-butylphenol</SPAN><IMG src="/images/empty.gif">

Chemicals Used

4-tert-butylphenol (Aldrich)
Acetonitrile (distilled over calcium hydride)
Triethylamine (distilled over calcium hydride
Anhydrous magnesium chloride (dried over phosphorus pentoxide)
Paraformaldehyde (dried in vacuum desiccator over phosphorus pentoxide)

Procedure

A 500 mL side arm round bottom flask with a stirrer bar was placed under argon and charged with 4-tert-butylphenol (3.00 g, 20.0 mmol) and dry acetonitrile (100 mL). To this was added dry Et3N (10.4 mL 75.0 mmol), anhydrous MgCl2 (2.86 g, 30.0 mmol) and the solution was stirred for 30 min. Dry paraformaldehyde (4.05 g 135.0 mmol) was added and a Schlenk condenser fitted to the round bottom flask. The mixture was heated to reflux under argon for ca 3h. The resulting yellow solution was allowed to cool to room temperature and was added to 5 % HCl (aq.) (200 mL) followed by stirring for 30 min. This was followed by extraction with diethyl ether (7 × 25 mL). The ether fractions were combined, washed with saturated NaCl (aq.) (3 × 20 mL) and the organic layer dried over anhydrous NaSO4 followed by filtration. All volatiles were removed under reduced pressure to yield a yellow oil which 1H NMR spectra showed to be 5-tert-butyl-2- hydroxybenzaldehyde (2.97 g, 83 %).

Author's Comments

Procedure was carried out under argon by using a dual manifold vacuum/argon line and standard Schlenk techniques.

Data

1H NMR (300 MHz, CDCl3): δ ppm 10.86 (s, 1H, ArOH), 9.87 (s, 1H, HC=O), 7.57 (dd, 1H, ArH) 7.50 (d, 1H, ArH), 6.92 (d, 1H, ArH), 1.31 (s, 9H, CMe3).

13C{1H} NMR 75 MHZ (CDCl3) δ ppm 190.7 (CHO), 159.3 (Ar-Cq-OH), 142.6 (Ar-Cq-tButyl), 134.6 (Ar-CH), 129.6 (Ar-CH), 119.8 (Ar-CH), 117.0 (Ar-CH), 33.9 (CMe3), 31.1 (CMe3).

MS (ESI): m/z 178 [M]+, 163 [M-CH3]+, 161 [M-OH]+, 148 [M-(CH3)2]+, 133 [M-(CH3)3]+


Lead Reference

N. U. Hofslokken and L. Skattebol, Acta Chem. Scand., 1999, 53, 258-262

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    Keywords: addition, alcohols, aldehydes, aromatics/arenes, formylation

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