Process for the production of chlorothalonyl

Details Process for the production of chlorothalonyl Process for the production of chlorothalonyl

1986-12-17

1990-07-17

Lee, Mary C.

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

Organic compounds

Nitriles

C07C12156

Patent

active

049422502

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to a process for the production of chlorothalonyl.


BACKGROUND ART

Chlorothalonyl (2,4,5,6-Tetrachloro-isophthalonitrile with formula ##STR1## is a fungicide widely used as anticryptogamic in agricultural cultivations and as antifungus for paints of various types.
After carrying out studies, the Applicant has been able to establish the existence of various crystallographyc structures of Chlorothalonyl, showing different physical behaviours and being more or less suited for producing compositions ready for use.
In particular, it has been established that there exists a crystallographyc structure--hereinafter called type I--which, when formed with suitable surface-active and suspending agents as known to the expert in the art, allows one to obtain flowables as well as water wettable powders, having optimal physical characteristics, remaining stable throughout time and having a high biological activity.
The X-ray diffraction spectrogram of said type I crystallographic structure shows some typical bands, as reported in Table 1.


TABLE 1 ______________________________________ X-ray diffraction spectrogram of Chlorothalonyl with type I crystallographic structure, in a decreasing order of intensity: Diffraction Interreticular angle (degrees) Intensity distances (.ANG.) ______________________________________ 51.2 100 3.48 56.0 60 3.19 28.8 36 6.15 62.3 35 2.87 63.6 35 2.81 40.1 30 4.42 40.7 30 4.37 ______________________________________
It has moreover been established that there is another crystallographic structure of Chlorothalonyl--hereinafter called type II--which is not suited, as it is, for producing compositions ready for use; in fact, various tests carried out on compositions including this type of Chlorothalonyl have showed the following: hardening, which can take place either after a few hours from preparation, or even after a few months, when the composition, initially deemed suitable for use, has already been delivered to the final users. be suspended in water may be greatly reduced, determining the formation of coarse flocculates and giving rise to difficulties of distribution when they are used.
The compositions produced starting from technical Chlorothalonyl with a type II crystallographic structure have also evidenced--parallely to a physical decay--a reduced biological activity in respect of similar compositions produced starting from Chlorothalonyl with a type I crystallographic structure.
The X-ray diffraction spectrogram of the type II crystallographic structure, widely differing from that of the type I structure, is reported in Table 2.


TABLE 2 ______________________________________ X-ray diffraction spectrogram of Chlorothalonyl with type II crystallographic structure, in a decreasing order of intensity: Diffraction Interreticular angle (degrees) Intensity distances (.ANG.) ______________________________________ 53.3 100 3.34 28.8 50 6.15 46.8 30 3.80 63.2 30 2.83 58.1 25 3.07 40.8 20 4.35 ______________________________________


DISCLOSURE OF THE INVENTION

To eliminate the drawbacks of Chlorothalonyl with a type II crystallographic structure, various production processes have been studied to obtain Chlorothalonyl having a type I structure, namely changing the type II crystallographic structure into a different structure, more suited for producing active compositions which remain stable throughout time.
It has unexpectedly been found that the type II crystallographic structure of Chlorothalonyl can be changed into a different more suitable structure, by supplying an appropriate amount of thermal and/or mechanical energy to said Chlorothalonyl, being distributed over a sufficient period of time.


BEST MODES FOR CARRYING OUT THE INVENTION

In particular, it has been found that, by heating the type II Chlorothalonyl, its crystallographic structure can be changed more quickly into a type I structure if operating while the product is being stirred, or else by simultaneously applying mechan

REFERENCES:
patent: 3839401 (1974-10-01), Lavergne et al.
patent: 3869494 (1975-03-01), Battershell
patent: 4485050 (1984-11-01), Casale et al.

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