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Preparation of N-(2-nitrophenyl)-9H-thioxanthen-9-amine from thioxanthen-9-ol and 2-nitroaniline; N-(2-nitrophenyl)-9H-thioxanthen-9-amine

SyntheticPage 845
DOI: 10.1039/SP845
Submitted Aug 14, 2018, published Sep 10, 2018
Robert Smith (, Mariyah Sajjad (), Mark Wainwright (, Joshua Gettins ()
A contribution from Smith Group

			Reaction Scheme: <IMG src="/images/empty.gif"><IMG alt="" src="/images/empty.gif"><IMG alt="" src="/images/empty.gif">Preparation of <SPAN id=csm1536587798284 class=csm-chemical-name title=N-(2-nitrophenyl)-9H-thioxanthen-9-amine><EM>N</EM>-(2-nitrophenyl)-9H-thioxanthen-9-amine</SPAN> from <SPAN id=csm1536587629183 class="csm-chemical-name csm-not-validated" title=thioxanthen-9-ol>thioxanthen-9-ol</SPAN> and <SPAN id=csm1536587632572 class="csm-chemical-name csm-not-validated" title=2-nitroaniline>2-nitroaniline</SPAN><IMG alt="" src="/images/empty.gif"><IMG alt="" src="/images/empty.gif"><IMG src="/images/empty.gif">

Chemicals Used

Thioxanthen-9-ol (prepared in house from thioxanthen-9-one - see Synthetic Page 848)

2-Nitroaniline (Sigma Aldrich)


To a round bottomed flask was added thioxanthen-9-ol (0.5 g, 2.3 mmol), 2-nitroaniline (0.4g, 2.9 mmol), acetic acid (0.25 mL) and ethanol (10 mL)*. The reaction mixture was fitted with a condenser and heated to reflux with constant stirring.**  After two hours at reflux, the solution was allowed to cool to room temperature, a glass stopper fitter and orange mixture transferred to a freezer and left overnight***.  The precipitate produced was isolated under vacuum filtration and washed with cold ethanol to give N-(2-nitrophenyl)-9H-thioxanthen-9-amine (0.16g, 20%) as an orange precipitate.

Author's Comments

* The whole reaction was accomplished in the open air without the need of dry/inert conditions.
** The reaction did not undergo TLC in the heating stage.
*** Leaving the reaction for an extra 24 hours in the freezer did not produce a higher yield, although a higher yield could possibly be obtained through evaporation of the reaction mixture and column chromatography.


1H NMR (400 MHz, DMSO-d6) δ 8.76 (d, J = 8.9 Hz, 1H), 8.06 (dd, J = 8.6, 1.6 Hz, 1H), 7.71 – 7.61 (m, 4H), 7.58 – 7.52 (m, 1H), 7.45 (dd, J = 8.9, 1.3 Hz, 1H), 7.37 – 7.32 (m, 4H), 6.74 (ddd, J = 8.4, 6.8, 1.2 Hz, 1H), 6.21 (d, J = 8.8 Hz, 1H).  13C NMR (101 MHz, DMSO) δ 143.40, 136.51, 134.84, 132.03, 131.71, 127.84, 127.68, 127.47, 127.03, 126.44, 116.35, 115.58, 54.87. LC-MS 335 [M+1].

Lead Reference

Hori, M., Kataoka, T., Ohno, K., Toyoda, T.; Reactivities of 9-​phenylxanthylium and 9-​phenylthioxanthylium salts in electrophilic and nucleophilic reactions.  I.  Nitration Chemical & Pharmaceutical Bulletin (1973), 21(6), 1272-1281.

Supplementary Information

1H NMR (1H.pdf)
13C NMR (13C.pdf)
135-DEPT NMR (135DEPT.pdf)
13C vs 135-DEPT (13C vs 135DEPT.pdf)
MS (MS.pdf)

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Get structure file (.cdx, .sk2, .mol)

Keywords: alcohols, amines, heterocyclic compounds

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