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The sulfonation of ortho toluidine and the preparation of sodium 6-chloro-5-nitro-meta-tolene sulfonate

Citation

Schultz, Murray Navarre (1927) The sulfonation of ortho toluidine and the preparation of sodium 6-chloro-5-nitro-meta-tolene sulfonate. Bachelor's thesis, California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-12062004-133814

Abstract

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Davies has pointed out that 6-chloro-5-nitro-m-toluenesulfonic acid may be used for separating potassium and rubidium on the one hand from lithium, sodium and cesium on the other, since the salts of the acid with the two former metals are very slightly soluble in water, while those with the three latter are quite soluble. It seemed desirable to study in more detail the steps involved in the preparation of the acid with the purpose of improving the procedures and increasing the yields at the different steps. We did not attempt to obtain the acid itself, but converted it instead into its sodium salt, which possesses a solubility markedly lower than that of the free acid and on that account separates more readily from aqueous solution.

The operations are as follows. [...]

o-Toluidine is first sulfonated to o-toluidine-5-sulfonic acid (II), which through the diazo reaction is converted into 6-chloro-m-toluenesulfonic acid (III). This with phosphorus pentachloride yields 6-chloro-m-toluenesulfonechloride (V) which is easily converted into sodium 6-chloro-5-nitro-m-toluenesulfonate (VI).

The first step, namely, the sulfonation of o-toluidine, was studied in detail. It was found that the presence of iodine, the use of which has been recommended by Ray and Dey, is a decided detriment, since it catalyzes the oxidation of the toluidine by the sulfuric acid and leads to considerable charring with decreased yields. Best results were obtained by the use of fuming sulfuric acid (20%) in the ratio of two moles of acid to one of toluidine, and heating on an oil-bath for ten hours at 180°.

In the second step, the replacement of an amino group by a chlorine atom through the diazo reaction with cuprous chloride present, practically quantitative results were obtained. It is not necessary, as Davies recommends, to remove copper from the filtrate in order to obtain subsequent crops of the chlorosulfonic acid (III), since the latter crystallizes in fairly pure condition as the liquid is evaporated.

In the third step, the conversion of the sulfonic acid (III) to the sulfone-chloride (IV), Davies obtained a practically quantitative yield, using, however, the sodium salt instead of the acid. His result is more satisfactory than that obtained with the free acid, but his procedure involves an additional step, namely, the conversion of the sulfonic acid to its sodium salt. The reaction of the acid with phosphorus pentachloride is carried out in the usual way.

The nitration of the sulfonechloride (IV) was done by following the directions of Davies and gave similar results.

The hydrolysis of the nitrated sulfonechloride (V) to the acid was also carried out as he directs, and the conversion of the latter to its sodium salt (VI) was a simple matter.

It is possible to obtain a 37% yield of the sodium salt (VI) from o-toluidine (I) by following the modified procedures as described below.

Item Type:Thesis (Bachelor's thesis)
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Lucas, Howard J.
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1927
Record Number:CaltechETD:etd-12062004-133814
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-12062004-133814
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4809
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:08 Dec 2004
Last Modified:26 Dec 2012 03:12

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