US2143963A - Process for the sulphonation of alpha nitro naphthalene - Google Patents

Description

Patented Jan. 17, 1939 UNITED STATES PROCESS FOR THE SULPHONATION 0F ALPHA NITRO NAPHTHALENE John M. Tinker, Perms Grove, N. J assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporati on of Delaware No Drawing. Application July 26, 1937, Serial N0. 155,780

7 Claims.

The present invention relates to a process for the production of nitro-naphthalene sulphonic acids. More particularly it relates to a process for the production of nitro-naphthalene sulphonic acids from nitro-naphthalene. Still more particularly it relates to an improved process for the production of 1-nitro-naphthalene-5-sul phonic acid from 1-nitro-naphthalene.

Nitrc-naphthalene sulphonic acids have been produced in the prior art by the sulphonation of l-nitro-naphthalene. Various sulphonating agents such as oleum, oleum plus sodium chloride, and chloro-sulphonic acid were employed in this prior art process but it was found that many unsatisfactory efiects resulted from their use. Thus, in the use of oleum and in the use of chlorosulphonic acid the reaction was found to be too vigorous, thereby resulting in charring, discoloration, and in very poor yields. Although the use of oleum plus sodium chloride gave a satisfactory yield there were still present other diificulties such as the evolution of hydrogen chloride in large quantities which caused serious corrosion and also, the presence of a toxic condition which condition proved to be dangerous to the workers.

It is an object of the present invention to manufacture nitro-naphthalene sulphonic acids by a simple and efficient process. A further object is to manufacture nitro-naphthalene sulphonic acid from nitro-naphthalene in the presence of a sulphonating agent. A still further object is to manufacture 1-nitro=-naphtha1ene-5-sulphonic acid from l-nitro-naphthalene. A still further object is to overcome the dificulties which were encountered in the prior art processes of making nitronaphthalene sulphonic acid. Additional objects will become apparent from a consideration of the following description and claims.

These objects are attained according to the herein described invention which broadly comprises sulphonating a nitro-naphthalene in the presence of a strong sulphonating agent and salt of a non-volatile acid. In a more restricted sense this invention comprises sulphonating nitronaphthelene, in the presence of a strong sulphonating agent and a salt of sulphuric acid. The preferred embodiment of this invention comprises sulphonating l-nitro-naphthalene in the presence of oleum and a salt of sulphuric acid. Exceptionally good results have been obtained by the use of sodium sulphate and for this reason, it is the preferred salt.

This invention may be more readily understood by a consideration of the following example.

Erample Heat a mixture of one thousand grams of 24% oleum, (76% H2SO4+24% free S03) 410 g. of an hydrous sodium sulphate and 500 g. of 100% sulphuric acid to -50" C, and add during one hour, 500 g. of l-nitro naphthalene. Heat the mass at -55 C. for 18 hours. Heat another hour at 85 0. Pour onto 10 liters of water, neutralize with lime and filter. On evaporation of the water the nitro-naphthalene calcium sulphonates are obtained in a quantitative yield. On reduction of the calcium or sodium salts of the mixed nitronaphthalene-sulphonic acids with iron and acid, mixed naphthylamine sulphonic acids are obtained from which of the theoretical yield of Laurents acid (l-naphthylamine-5-sulphonic acid) can be isolated by known methods.

It is seen from an examination of the above example that Laurents acid may'be obtained by reducing with iron and sulphuric acid the nitronaphthalene sulphonic acid followed by extraction of the Laurents acid from the iron sludge with sodium carbonate solution.

It is to be understood that the aforementioned example is representative only of the method of the practice of the invention. This method may be subjected to variation and modification. For instance in place of sodium sulphate, referred to in the preceding example, or in admixture therewith it is to be understood that salts of other nonvolatile acids or other salts of sulphuric acid may be used. A few representative examples of materials falling within this category are sodium bisulphate, ammonia salts of non-volatile acids, alkali metal and alkaline earth metal salts of non-volatile acids such as sulphuric, boric, phosphoric, naphthalene sulphonic, and the like. The alkali and alkaline earth sulphates and bisulphates generally as well as the sulphates and bisulphates of related metals have been found to give excellent results. As previously mentioned, these salts may be used alone or in admixture with one another and when used in admixture with one another the proportions may vary widely without departing from the scope of this invention. However, it is to be understood that sodium sulphate is the preferred salt for use herein.

The proportion of the salt to the sulphonating agent and the proportion of the sulphonating agent to the nitro-naphthalene may vary widely Without departing from the scope of this invention. However, the preferred results have been obtained when the molar ratio of the salt to sulphur tri-oxide and of the sulphur tri-oxide to nitro-naphthalene has been within the range of 1 to 3 moles of salt to 1 mole of sulphur tri-oxide and 1 to 3 moles of sulphur tri-oxide to 1 mole of nitro naphthalene.

It is preferred to use the aforementioned salts in the anhydrous form because an increased amount of oleum is required when the Wet salt is used. However, it is to be understood that the salt in the hydrated form may be used without departing from the scope of tlr's invention.

The term oleum as used in the disclosure as well as the appendant claims means sulphuric acid containing free sulphur tri-oxide.

By means of the present invention an entirely new class of salts are used in the production of nitro-naphthalene sulphonic acid. Due to the presence of said salts in the sulphonation of nitronaphthalene it is possible to produce nitro-naphthalene sulphonic acid by a process which is superior and more economical than any heretofore known. Further, the defects of vigorous reactions, charring, discoloration, poor yield, formation of hydrogen chloride, toxic condition, etc. are overcome by my herein disclosed invention.

As many apparently widely different embodiments of this invention may be made without departing from the scope and spirit thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

Having disclosed the present invention the following is claimed as new and useful:

1. A process which comprises sulphonating a nitro-naphthalene in the presence of a mixture of a strong sulphonating agent and a salt of sulphuric acid selected from the class consisting of alkali metal, alkaline earth metal, and ammonium salts.

2. A process which comprises sulphonating a Intro-naphthalene in the presence of a mixture of oleum and a salt of sulphuric acid selected from the class consisting of alkali metal, alkaline earth metal, and ammonium salts.

3. A process which comprises sulphonating a nitro-naphthalene in the presence of a mixture of oleum and sodium sulphate.

4. A process which comprises sulphonating lnitro-naphthalene in the presence of a mixture of oleum and sodium sulphate.

5. A process which comprises sulphonating a nitro-naphthalene in the presence of a mixture of a strong srulphonating agent and salt of a nonvolatile acid selected from the class consisting of alkali metal, alkaline earth metal, and ammonium salts of sulphuric, boric, phosphoric and sulphonic acids.

6. A process which comprises sulphonating nitro-naphthalene in the presence of a mixture of oleum and sodium sulphate, in the absence of any volatile acid, the molar ratio of the salt to sulphur tri-oxide and of the sulphur tri-oxide to nitronaphthalene being within the range of l to 3 moles of salt to 1 mole of sulphur tri-oxide and 1 to 3 moles of sulphur tri-oxide to 1 mole of nitro-naphthalene.

'7. A process which comprises sulphonating 1- nitro-naphthalene in the presence of a mixture of oleum and sodium sulphate, in the absence of a volatile acid, the molar ratio of the salt to sulphur tri-oxide and of the sulphur tri-oxide to nitronaphthalene being within the range of 1 to 3 moles of salt to 1 mole of sulphur trioxide and 1 to 3 moles of sulphur tri-oxide to 1 mole of nitro-naphthalene.

J OHN M. TINKER.

CERTIFICATE OF CORRECTION,

Patent No. 2,lh5,965c January 17, 19590 JOHN M. TINKER. I

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 6, for "1 0- 50 C." read hO-Lfi C. and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of February, A. D. 1959.

Henry Van Arsdale.

(Seal) Acting Commissioner of Patents.