Claims
- 1. A process for separating 2,6-naphthalenedisulfonic acid from a reaction mixture resulting from the disulfonation of naphthalene, which comprise the steps of:
- (a) disulfonating naphthalene under .beta.,.beta.-disulfonation reaction conditions in order to obtain a reaction mixture containing predominantly 2,6-naphthalenedisulfonic acid and 2,7-naphthalenedisulfonic acid therein;
- (b) adding water to said reaction mixture obtained by said disulfonation of naphthalene in order to adjust to 50 to 70% by weight the sulfuric acid concentration in said reaction mixture;
- (c) maintaining the reaction mixture at a temperature of 0.degree. to 70.degree. C.; and
- (d) separating away precipitated crystals of 2,6-naphthalenedisulfonic acid.
- 2. A process as in claim 1 wherein said reaction mixture is maintained at a temperature of 0.degree. to 70.degree. C.
- 3. A process as in claim 1 wherein said sulfuric acid concentration is adjusted to 50 to 75% by weight and said reaction mixture is maintained at a temperature of 20.degree. to 50.degree. C.
- 4. A process for separating 1,6-naphthalenedisulfonic acid from a reaction mixture resulting from the disulfonation of naphthalene, which comprises the steps of:
- (a) disulfonating naphthalene under .alpha.,.beta.-disulfonation reaction conditions, in order to obtain a reaction mixture containing predominantly 1,6-naphthalenedisulfonic acid and 1,7-naphthalenedisulfonic acid and minor amounts of 2,6- and 2,7-naphthalenedisulfonic acids;
- (b) adding water to said reaction mixture obtained by disulfonation of naphthalene in order to adjust to 35 to 90% by weight of sulfuric acid concentration in said reaction mixture;
- (c) maintaining said reaction mixture at a temperature of 0.degree. to 80.degree. C.; and
- (d) separating away precipitated crystals of 1,6-naphthalenedisulfonic acid.
- 5. A process as in claim 4 wherein said sulfuric acid concentration is adjusted to 45 to 60% by weight.
- 6. A process as in claim 4 wherein said reaction mixture is maintained at a temperature of 20.degree. to 60.degree. C.
- 7. A process as in claim 4 wherein said sulfuric acid concentration is adjusted to 45 to 60% by weight, and said reaction mixture is maintained at a temperature of 20.degree. to 60.degree. C.
- 8. A process for separating 2,7-naphthalenedisulfonic acid from a reaction mixture resulting from the disulfonation of naphthalene, which comprises the steps of:
- (a) disulfonating naphthalene under .beta.,.beta.-disulfonation reaction conditions in order to obtain a resulting reaction mixture containing predominantly 2,6-naphthalenedisulfonic acid and 2,7-naphthalenedisulfonic acid therein;
- (b) adding water to said reaction mixture obtained by said disulfonation of naphthalene in order to adjust to 35 to 45% by weight the sulfuric acid concentration within said reaction mixture;
- (c) maintaining said reaction mixture at a temperature of 0.degree. to 50.degree. C.; and
- (d) separating away precipitated crystals of 2,7-naphthalenedisulfonic acid.
- 9. A process according to claim 8 wherein said reaction mixture is maintained at a temperature of 20.degree. to 40.degree. C.
- 10. A process as in claim 8 wherein said sulfuric acid concentration is adjusted to 35 to 45% by weight and the reaction mixture is maintained at a temperature of 20.degree. to 40.degree. C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
53-72622 |
Jun 1978 |
JPX |
|
Parent Case Info
This application is a continuation-in-part of Ser. No. 048,247 filed June 13, 1978 now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
2125189 |
Lofton et al. |
Jul 1938 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
2028308 |
May 1980 |
GBX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
48247 |
Jun 1978 |
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