dragonfly
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1-iodo-4-nitrobenzene
Is anyone able to supply the preperation procedure for 1-iodo-4-nitrobenzene from nitroaniline via diazo. I have attempted this reaction several times
being frustrated by a yeild of tan powder i am assuming is 4-nitrophenol. Please reply to crdevo@yahoo.com
[Edited on 5-9-2006 by dragonfly]
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Nicodem
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| Quote: | Originally posted by dragonfly
Please reply to crdevo@yahoo.com |
No, I will not. It is considered very impolite to ask on a public forum to be emailed the answer.
This is also the wrong subforum. This post should be in “Organic chemistry” subforum.
Two minute googling brought out this:
US6943257: Synthesis of 1-iodo-4-nitrobenzene
The same procedure as Example 11 was repeated except that 4-aminobenzophenone was substituted with 4-nitroaniline (0.691 g, 5 mmol) as the starting
material. The yield determined by gas chromatography was 89% (based on decane as an internal standard).
1H-NMR (CDCl3): 7.88 (d, 2H), 8.01 (d, 2H).
Example 11: Synthesis of 4-iodobenzophenone
A solution of 57% aqueous HI (3.29 ml, 25 mmol) dissolved in DMSO (25 ml) was added dropwise to a solution of 4-aminobenzophenone (0.986 g, 5 mmol) in
a mixture of 25 ml of DMSO and KNO2 (0.851 g, 10 mmol) at 35° C. with agitation. The added mixture was stirred at 35° C. for 10 minutes and then was
transferred to a solution containing K2CO3 (5 g) in 100 ml ice-water. The reaction mixture was then taken up in ether, and then the ethereal extracts
were washed with water and dried over anhydrous magnesium sulfate. Removal of the solvent under reduced pressure gave the crude 4-iodobenzophenone.
The crude product was further purified by column chromatography to obtain 4-iodobenzophenone. The yield determined by gas chromatography was 88%
(based on decane as an internal standard).
See also: http://www.orgsyn.org/orgsyn/orgsyn/prepcontent.asp?print=1&...
_______________________
PS: Posting questions without providing the necessary details is also considered impolite. What reaction procedure have you used? What makes you
assume that what you got is 4-nitrophenol? What’s the m.p. of the product? Does it have any phenol-like properties (soluble in bases, complexes with
FeCl3, etc.)? What procedures are you aware of, so that we don’t bother replying with references you already have… and so on.
[Edited on 5-9-2006 by Nicodem]
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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cuprate
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The best yield I have seen so far is 100 % (Can you believe this??) described in "Waste-free chemistry of diazonium salts and benign separation of
coupling products in solid salt reactions", Kaupp, Gerd; Herrmann, Andreas; Schmeyers, Jens. Universitat Oldenburg FB Chemie, Organische Chemie I,
Oldenburg, Germany. Chemistry--A European Journal (2002), 8(6), 1395-1406. THis is a very cool paper.
The general procedure is: Nitroaniline (360 mg,
2.00 mmol) was cooled to 5 C. NO2 (1 g) was condensed in a vacuum line
onto the crystals that slowly dissolved overnight at 5 C in a refrigerator.
Excess NO2 was recovered at 10 C by condensing into a cold trap at 77 K
for further use. The acetic acid was removed in a vacuum at 25 C (it might
be used or neutralised with NaOH). The quantitatively obtained diazonium
nitrate (212 mg, 100%) was characterised by its IR and NMR spectra.
KI (830 mg, 5.0 mmol) was finely ground
in an agate mortar and the diazonium salt (0.50 mmol) added in five
portions and co-ground for 5 min each. After a 24-h hour rest with
occasional grinding, the diazonium band in the IR spectra had completely
disappeared. The potassium salts were removed by washing with cold
water.Yield: 124 mg (100%); m.p. 172 C ; IR (KBr): 1594, 1571, 1513, 1469, 1411, 1391, 1353, 1340,
1308, 1272, 1178, 1105, 1052, 1008, 851, 837, 735, 674 cm1; 1H NMR
(CDCl3): 7.8 ± 8.0 (AABB system); MS (CI, isobutane): m/z: 250
[M+H].
Be extrememly careful with the dry diazonium salt. It is explosive.
| Quote: | Originally posted by dragonfly
Is anyone able to supply the preperation procedure for 1-iodo-4-nitrobenzene from nitroaniline via diazo. I have attempted this reaction several times
being frustrated by a yeild of tan powder i am assuming is 4-nitrophenol. Please reply to crdevo@yahoo.com
[Edited on 5-9-2006 by dragonfly] |
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dragonfly
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I apologise for requesting an email response (some what new at this) the procedure I used is as follows. Method:
diazo-salt:
In a erlenmeyer flask mix 67ml water with 16ml(0.3mol) concentrated sulphuric acid. Add to the acid mix 11g (0.08mol) p-nitroaniline warm the mixture
to effect dissolution. Stir for 15min.
Cool the mixture to 5degC
To the cooled mixture add a solution containing 5.6g (0.08mol) sodium nitrite in 28ml water keep solution at 5deg C
Iodisation:
Cool the diazonium salt mix to -10 then(salt/icebath) add to the the cold diazonium salt 37g(0.22mol) potassium iodide(as solid) in portions. Mix for
45 min. Let the mixure stand stirring occasionally until the evolution of nitrogen ceases. Vacuume filter of the solid, wash twice with cold water.
Dry by vacuume, recrystalise from 95% ethanol
My melting point was between 130deg c and 134deg c for the first sample and 170- 174 for the second attempt. (second attempt was dissolved in DCM to
remove the water thouroughly)
I thought I had nitrophenol by the initial melting point and by the tan colour (msds discription)
I thank you again Nicodem and Cuprate for your time and will be sure to use the organic chem forum in future
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Nicodem
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Both runs gave a product with a m.p. much higher than the 110-115 °C of p-nitrophenol.
The first sample gave a product whose m.p. is near to that of p-nitroaniline (146-149 °C) but the melting interval you gave is too narrow for having
an m.p. depression caused by impurities. Besides I don’t see how p-nitroaniline could come out of the reaction unchanged. So I have no idea what it
was.
The second sample fits the m.p. of 1-iodo-4-nitrobenzene (171-173°C) excellently.
Before the water washes you should have washed the crude product with NaHCO3 until the filtrate is clear of yellow color if p-nitrophenol
contamination is what you fear. If the filtrate is colorless then there is no p-nitrophenol there. Though, there would have to be a lot of
p-nitrophenol to come across a recrystallization. Can’t really say what was wrong with your first sample.
(m.p. data taken from Sigma)
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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dragonfly
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I found this procedure and substituted 6-methyl-2-nitroaniline with 4-nitroaniline. The yeild was good.
http://www.syntheticpages.org/search.php?&action=1&p...
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