CS230942B1 - Process for preparing 2,2'-dinaphthyl sulfone - Google Patents

Abstract

A method for preparing 2,2-dinaphthyl sulfone by mixing 1,1- or 1,2'-dinaphthyl sulfone, or a mixture thereof, with 98% sulfuric acid, after heating to 140 to 180 °C, preferably within 4 to 6 hours, the melt is cooled, diluted with water and the product is extracted with an aromatic solvent, preferably toluene. The prepared substance is a starting compound for the synthesis of 1,4-thiaphosphorine trioxide.

Description

The present invention relates to a process for the preparation of 2,2'-dinaphthylsulfone. The substance has not yet been prepared in a reproducible manner. It has now been found that the reaction of 1,1'- or 1,2'-dinaphthylsulfones with concentrated sulfuric acid gives pure 2,2'-dinaphthylsulfone.

2,2'-dinaphthylsulfone is the starting compound for the synthesis of 1,4-thiaphosphorin trioxide, in general diarylsulfones are useful for drug synthesis.

Some side reactions may occur during the sulfonation of naphthalene which do not give rise to the desired naphthalene sulfoacid. One of the side reaction products is dinaphthylsulfones. Their formation can be explained either by reacting two sulfoacid molecules to form sulfuric acid or by reacting the sulfoacid with a hydrocarbon to form water. Another method suitable for the preparation of diarylsulfones, particularly asymmetric, is the reaction of sulfonyl chlorides with aromatic hydrocarbons in the presence of anhydrous aluminum chloride. Similarly to the formation of 1- or 2-sulfoacid according to the reaction conditions in the naphthalene sulfonation, three isomers can be expected to be formed, namely 1,1 1,2'-, 2,2'-dinaphthylsulfone.

The process for the preparation of 2,2'-dinaphthylsulfone according to the invention consists in mixing 1,1'- or 1,2'-dinaphthylsulfone or a mixture thereof with 98% sulfuric acid, after heating to 140 to 180 ° C, preferably during After 4 to 4 hours, the melt is cooled, diluted with water and the product extracted with an aromatic solvent, preferably toluene. The constitution of the product after crystallization was verified by NMR.

The examples below illustrate embodiments of the invention.

Example 1

To 6 g of 1,1'-dinaphthylsulfone was added 2 g of 98% sulfuric acid and the mixture was heated to 160 ° C for 5 hours. After the reaction time, the mixture was diluted with water and the organic layer was extracted with toluene. After crystallization, 5.8 g of 2,2'-dinaphthylsulfone were obtained.

Example 2

To 6 g of 1,2-dinaphthylsulfone was added 2 g of 98% sulfuric acid and the mixture was heated to 160 ° C for 4.5 hours. After the reaction time, the mixture was diluted with water and the organic layer was extracted with toluene. After crystallization, 5.8 g of 2,2'-dinaphthylsulfone were obtained.

The constitution of the obtained compounds was verified in both cases by NMR method.

Identification of isomeric dinaphthylsulfones and determination of their ratio in the ¹ H-HMR spectrum of deuteriochloroform sample solutions with hexamethyldisiloxane internal standard was recorded with JNM-F-100 (Jeol, Tokyo) and the aromatic proton signals were integrated at 250 Hz recording width.

Spectra of pure isomer spectra vary significantly in the range 6-8.80 to 8.40:

1,1'-dinaphthylsulfone-ortho-doublets (J-8.0 Hz) with meta-cleavage (J-1.5 Hz), center 0-8.61, area 4 H (protons H / 2 /, H / 2 ' /, Η / β /, Η / β '/ λ

1,2'-dinaphthyleulfone - complex multiplet with peaks δ-8.74; -8.61; - 8.51; flat

H (protons H / 2 /, Η / Θ /, Η / Θ / Ί;

2,2'-dinaphthylsulfone-meta-doublet; center δ-8.59; area 2 H (protons H / 1, H (1 ');

Further, 2,2'-dinaphthylsulfone is characterized by a meta-doublet having a center of δ-7.84, while 1,2'-dinaphthylsulfone has an intense meta-doublet of δ-7.72.

The ratio of isomers can be approximately determined by comparing the signal areas in the areas:

A · · · 6 = 8.80 to 8.40} Β. ·. δ - 8.20 to 7.65} C · · · δ = 7.65 to 7.35. The total area is identical for all isomers A + B + C = 14 H;

Relative surfaces

1,1'-dinaphthylsulfone

1,2'-dinaphthylsulfone 2,2'-dinaphthylsulfone

ABC

6 4 3 6 5 2 8 5

The representation of individual isomers can then be calculated by solving the equations:

4 and + 3 a / 3 + 2β = 14 6 and + 6 αβ + 3b = 14 4 and + 5αβ + 4 (8 = 14

a / (a + b + c); b / (a + b + c); c / (a-b-c);

where 100 a corresponds to the percentage of 1,1'-dinaphthylsulfone,

100 and β correspond to the percentage of 1,2'-dinaphthylsulfone and 100 µ8 to the percentage of 2,2'-dinaphthylsulfone.

Claims (1)

SUBJECT OF THE INVENTION Process for the preparation of 2,2'-dinaphthylsulfone, characterized in that 1,1'-or 1,2'-dinaphthylsulfone or a mixture thereof is admixed with 98% sulfuric acid, after heating to 140-180 ° C, preferably within 4-7 ° C. The melt is cooled for 6 hours, diluted with water and the product extracted with an aromatic solvent, preferably toluene.