Process for the manufacture of a sulfenimide

Details Process for the manufacture of a sulfenimide Process for the manufacture of a sulfenimide

1999-04-16

2001-02-06

Gerstl, Robert (Department: 1613)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C564S102000

Reexamination Certificate

active

06184385

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a process for preparing a sulfenimide from a sulfenamide employing a novel method for recovering the product from the reaction mixture.
BACKGROUND OF THE INVENTION
Santocure® TBSI (N-t-butyl-2-benzothiazole sulfenimide) is a good replacement for secondary amine based sulfenamide accelerators which are under close environmental scrutiny due to potential nitrosoamine generation during the processing and curing of rubber. Santocure® TBSI has a long scorch delay and slow cure rate which mimics the secondary amine based sulfenamide accelerators.
It is known to manufacture Santocure® TBSI from N-t-butyl-2-benzothiazole sulfenamide (Santocure® NS) and gaseous hydrogen chloride with heptane used as the solvent as shown by the following reaction:
The prior art process involves filtration of heptane slurry to give a crude product which is fully dried and then reslurried in water at 50° C. and then filtered and dried to give a final product. The heptane is recovered by distillation and the heptane still bottoms are incinerated. Thus, this process involves two filtration and two drying steps and recovery of heptane by distillation. This two step filtration/drying process has heretofore been considered to be the only practical means of transferring the Santocure® TBSI from the solvent phase to the aqueous phase.
For example, U.S. Pat. No. 5,204,481 provides a typical description of the known process in Examples 1 and 2. The reactor mixture is first subjected to a vacuum filtration to separate mixed reaction solids from heptane, the solids are washed and dried and the dry mixed solids are slurried in water to dissolve the hydrochloride salt. The product is then isolated by a further vacuum filtration, water washing and drying.
The prior art process does produce Santocure® TBSI in high yields and high assay, but as previously mentioned, it demands two filtration and two drying steps. Overall, the prior art process is complicated and inefficient, thereby creating a long felt but heretofore unfulfilled need for process improvements.
SUMMARY OF THE INVENTION
Accordingly, the present invention comprises a process for the manufacture of a sulfenimide from an sulfenamide. The sulfenamide in slurry with a water immiscible organic solvent is reacted with an acid to yield a solvent slurry comprising the sulfenimide product. The product is recovered from the solvent slurry by a method comprising the addition of water to the solvent slurry and the isolating of the product by a single filtration step.
More detailed embodiments of the invention will be described hereinbelow, particularly with regard to recovery of product from the reaction mixture.


REFERENCES:
patent: 5204481 (1993-04-01), Carroll
patent: 5286870 (1994-02-01), Sichender

Affiliated with

Also associated with

Rating

Process for the manufacture of a sulfenimide does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the manufacture of a sulfenimide, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the manufacture of a sulfenimide will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2595986