((5-Nitro-2-thiazolyl)thio)polyhalogenated pyridines
SUMMARY OF THE INVENTION 
     The novel compounds of the present invention, hereinafter alternatively referred to as &#34;active compounds&#34;, correspond to the formula ##STR2## wherein x is 3 or 4. 
     The active compounds, directly or as active ingredients in formulations and compositions, exhibit, when used in antimicrobially-effective amounts, antimicrobial activity against fungi and bacteria. Hereinafter the terms &#34;antimicrobial&#34; and &#34;antimicrobially-effective&#34; when used in conjunction with the active compounds will be employed to identify their activity against fungi and/or bacteria. 
     The active compounds are prepared by reacting sodium methoxide with the corresponding polychloro-4-mercaptopyridine in methanol and reacting the thus-formed mixture with 2-bromo-5-nitrothiazole. The reaction mixture is maintained at about 0° C. to about 60° C., with agitation until substantial completion of the reaction, usually from about 1 to about 20 hours. The product compound is recovered and purified by conventional techniques known to those in the art. 
     Ordinarily substantial equimolar proportions of the starting materials are employed in the above-described process. However, any of the starting materials can be used in excess of the equimolar stoichiometric requirement. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following examples and teachings illustrate the present invention and the manner by which it can be practiced but as such should not be construed as limitations upon the overall scope of the same. The product compounds are identified by elemental anaylsis, nuclear magnetic resonance spectroscopy (NMR) and infrared spectroscopy (IR). 
    
    
     EXAMPLE 1 - 
     Preparation of 2,3,5,6-tetrachloro-4-((5-nitro-2-thiazolyl)thio)pyridine (Compound 1) 
     A 0.04 mol (9.95 g) quantity of 2,3,5,6-tetrachloro-4-mercaptopyridine stirred in 300 ml of methanol was treated with 2.16 g (0.04 mol) of sodium methoxide, forming the insoluble thiolate. To this mixture at room temperature (22° C.), 8.3 g (0.04 mol) of 2-bromo-5-nitrothiazole was added. The reaction mixture is stirred for an additional 20 hours at ˜22° C. at which time the methanol was reduced to 1/2 its original volume. The precipitated solids were collected by filtration and washed with water. Recrystallization from methanol yielded 4.5 g (30 percent yield from the mercaptopyridine) of yellow crystals, m.p. 88° C.-88.5° C. 
     A sample was subjected to elemental anaylsis. The results obtained were as follows: 
     Analysis for C 8  HCl 4  N 3  O 2  S 2  : 
     Calcd: C, 25.5; H, 0.26; N 11.2; Found: C, 25.37; H, 0.40; N, 11.27. 
     NMR and IR confirmed the assigned structure. 
     EXAMPLE 2 - 
     2,3,5-Trichloro-4-((5-nitro-2-thiazolyl) thio)pyridine (Compound 2) 
     The product compound was prepared by the procedure of Example 1, from 2,3,5-triochloro-4-mercaptopyridine. The crude product was an oil which was purified by removal of methanol, dissolution into methylene chloride, washing with water, drying over magnesium sulfate, evaporation of solvent, and drying in vacuo to constant weight to yield 61 percent of a viscous orange liquid. 
     Analysis for C 8  H 2  cl 3  N 3  O 2  S 2  : 
     Calcd: C, 28.05; H, 0.60; N, 12.26;Found: C, 27.95; H, 0.73; N, 12.48. 
     NMR and IR confirmed the assigned structure. 
     The active compounds of the invention are suitable for use as antimicrobials for the control of bacteria and fungi. This is not to suggest that the active compounds and mixtures thereof with usual additives are equally effective against all such organisms at the same concentration. For such uses, the active compounds can be employed in an unmodified form or dispersed on a finely divided solid and employed as a dust. Such mixtures can also be dispersed in water with the aid of a surface-active agent and the resulting emulsion employed as a spray. In other procedures, the active compounds can be employed as the active constituents in solvent solutions, oil-in-water or water-in-oil emulsions. The augmented compositions are adapted to be formulated as concentrates and subsequently diluted with additional liquid or solid adjuvants to produce the ultimate treating compositions. Good control and kill have been realized against a number of representative organisms with compositions wherein antimicrobially-effective amounts of from about 0.5 to about 500 parts by weight of one or more of the active compounds per million parts of such compositions are employed. As stated hereinbefore the active antimicrobially-effective amount to be employed against a given organism or in a certain composition can readily be determined by one skilled in the art. 
     Incorporation of the active compounds of this invention into materials which are subject to fungal attack inhibits the growth of the fungi and preserves the original value of the materials. The active compounds are sufficiently nonvolatile and water-insoluble so that they will persist on or in such materials for long periods of time. Examples of materials which are adversely affected by fungal growth are latex and alkyl paint films, wood and wooden products. The active compounds are sufficiently active against fungi such that only small quantities are required to prevent mildew on paint films or wood rot. The active compounds are therefore useful for long-term protection against fungal growth in or on materials having a wood basis or a protective or decorative paint film or other coating or covering subject to fungal attack. 
     In a standard activity test, samples of each of Compounds 1 and 2 were individually dispersed in warm melted nutrient agar which was poured into petri dishes and allowed to solidify, the active compounds being employed in an amount sufficient to provide from 0.5 to 500 parts by weight thereof per million parts (ppm) of the ultimate agar composition. The surface of the agar was inoculated with a variety of bacterial and fungal pest organisms, and the inoculated plates incubated under conditions conducive to bacterial and fungal growth. Similar check plates in which the agar did not contain the active compounds or other toxic compounds were similarly inoculated and incubated. 
     In these studies, Compounds 1 and 2 gave 100 percent growth inhibition (kill) and control of the following organisms at the indicated concentrations in parts per million (ppm): 
     
                       TABLE                                                       
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ANTIMICROBIAL ACTIVITY                                                    
             Concentration in ppm                                         
Organism       Compound 1   Compound 2                                    
______________________________________                                    
S. aureus      0.5          0.5                                           
S. typhosa     0.5          5                                             
S. subtilis    0.5          0.5                                           
C. albicans N  5            5                                             
C. albicans D  1            5                                             
C. pelliculosa 5            5                                             
Torulopsis specie                                                         
               0.5          5                                             
P. pullalans   5            0.5                                           
C. ips         0.5          0.5                                           
T. mentagrophytes                                                         
               0.5          0.5                                           
P. chrysogesum 0.5          0.5                                           
Tri-sp-mad-P-42                                                           
               5            5                                             
A. Fumigatus   0.5          0.5                                           
A. niger       0.5          0.5                                           
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     Preparation of the Starting Materials 
     The polychloromercaptopyridine starting materials may be prepared by the procedure taught by H. Johnston in U.S. Pat. No. 3,364,223.