Europa,schesP_ MM M II M MM IN Ml MM I M Ml J European Patent Office _ _ _ © Publication number: 0 378 303 B1 Office_„. europeen des brevets EUROPEAN PATENT SPECIFICATION © Date of publication of patent specification: 05.04.95 © Int. CI.6: A01 N 57/02 © Application number: 90300080.0 @ Date of filing: 04.01.90 © Inhibition of mercaptan odor in organothiophosphate biocides. © Priority: 04.01.89 US 293244 © Proprietor: ZENECA LIMITED 15 Stanhope Gate @ Date of publication of application: London W1Y 6LN (GB) 18.07.90 Bulletin 90/29 @ Inventor: Chen, Chia-Chung © Publication of the grant of the patent: 124 Farragut Street 05.04.95 Bulletin 95/14 Hercules, California 94547 (US) Inventor: Rider, Richard H. © Designated Contracting States: 1308 Norvell Street AT BE CH DE DK ES FR GB GR IT LI LU NL SE El Cerrito, California 94530 (US) Inventor: Lo, Ray J. © References cited: 2908 Bayview Drive EP-A- 0 210 608 Alameda, California 94501 (US) FR-A- 2 196 751 CENTRAL PATENTS INDEX, BASIC AB- © Representative: Bishop, Nigel Douglas et al STRACTS JOURNAL, section C, 1967, ab- Intellectual Property Department stract no.67-8304g, Derwent Publications Ltd, ZENECA Agrochemicals London, GB; & JP-A-42 003 381 Jealotts Hill Research Station P.O. Box 3538 CHEMICAL ABSTRACTS, vol. 99, no. 6, 8th Bracknell August 1983, page 147, abstract no. 40962r, Berkshire RG12 6YA (GB) Columbus, Ohio, US; 00 00 o 00 00 00 Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid (Art. 99(1) European patent convention). Rank Xerox (UK) Business Services (3. 10/3.09/3.3.3) EP 0 378 303 B1 Description This invention relates to thiophosphate biocides, and in particular to agricultural formulations of biocidal thiophosphates which have a tendency to emit mercaptan vapors. 5 Organothiophosphate insecticides are well known and widely used for crop protection. Included among these are terbufos, phorate, ethoprop, dialifos, carbophenothion, ethion, dioxathion, fonofos and phosmet. An unfortunate aspect of many of these compounds is a mercaptan odor. The presence of mercaptans in compositions or formulations of these compounds is due to a number of factors. In some cases, the mercaptans serve as starting materials for the synthesis of these compounds, and their presence in the final io product is the result of trace amounts of unreacted starting material. These compounds also tend to degrade or decompose to produce mercaptans, particularly when subjected to heating or conditions promoting acid hydrolysis. Still further, thiophosphite analogs of the compounds are present in some cases as by-products of the synthesis, and these thiophosphite species have a high tendency to decompose to mercaptans. Regardless of the mechanism by which the mercaptan odor is produced, it is undesirable from 75 an environmental point of view as well as for handling and field application purposes. It has now been discovered that mercaptan odor development in an organothiophosphate compound or formulation is suppressible by treatment of the compound during preparation of the formulation in which it will be applied. In particular, it has been discovered that certain treatment agents may be applied to the compound during its formulation procedure to remove any mercaptan present and any other species having 20 a high tendency to release mercaptan. These agents, which may be applied individually or in combination, include molecular iodine and triodide. The treatment method will vary depending on the agent used, in accordance with the treatment mechanism. Similarly, the type of formulation to which the treatment may be applied may vary as well. The result in any case is a formulation which is initially free of mercaptan odor and in which the timewise development of mercaptan odor is inhibited if not eliminated entirely. 25 In the present invention the thiophosphate composition is treated with iodine to accelerate any latent mercaptan production in the composition. This treatment is particularly effective in compositions where mercaptan production is primarily the result of thiophosphite impurities included with the thiophosphate. The iodine is added in the zero-valent form. Examples include molecular iodine (b) and triiodide. In preferred embodiments, the iodine is applied as molecular iodine in a non-polar solvent. Examples of such 30 solvents are paraffins, toluene, xylenes and aromatic naphthas, notably heavy aromatic naphthas. The method of treatment is not critical and may vary widely. For example, a two-phase system may be used, whereby the thiophosphate is present as a solution in a non-polar organic solvent and the triiodide is present in polar agueous solution. The two phases are brought into contact in a manner sufficient to achieve maximal interfacial contact, then phase separated. 35 Any generated mercaptan which remains in the non-polar organic phase may then be removed by conventional means, such as distillation. Alternatively, excess iodine may be used to convert the undistilled mercaptan to the corresponding disulfide. The disulfide will be odorless and may thus be retained with the thiophosphate, rather than removed. For this alternative, the iodine is preferably used as a solution in a polar solvent. 40 The polar solvent may be any conventional, inert, and otherwise agriculturally acceptable material. Examples are water and polyols such as ethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, dibutylene glycol, hexylene glycol and triethanolamine. The polyols are further useful as stabilizing agents for granular products of the thiophosphate on clay to inhibit the decomposition of the thiophosphate to generate mercaptans. 45 In particularly preferred embodiments of this aspect of the invention, the thiophosphate compound (including impurities such as unreacted starting material, synthesis by-products, and degradation products) is combined with small amounts of iodine, polar stabilizer, and non-polar solvent, and agitated to first release mercaptan and to subsequently convert mercaptan to disulfide, then combined with an inert diluent or carrier as typically included in an agricultural formulation. 50 The relative amounts of these components are not critical, and may vary widely. The optimal amount of iodine used will of course be selected in accordance with the amount of mercaptan or thiophosphite by- product included with the thiophosphate, and whether or not the iodine is also intended to oxidize the resulting mercaptan to the disulfide form. Likewise, the optimal amount of solvent and stabilizer will depend on economic and activity considerations as well as the type of formulation ultimately prepared. In most 55 applications, an amount of iodine which comprises from about 0.1 to about 10 parts by weight per 100 parts by weight of the active ingredient (i.e., the thiophosphate itself), preferably from about 0.3 to about 3 parts per 100 parts, will provide the best results. Similarly, formulations where the nonpolar solvent and the polar stabilizer each comprise from about 5 to about 100 parts by weight per 100 parts by weight of the active 2 EP 0 378 303 B1 ingredient, preferably from about 20 to about 60 parts per 100 parts, will generally provide the best results. A typical formulation, for example, may be a granular formulation in which the iodine comprises about 0.1- 0.3%, the active ingredient about 15.23%, the non-polar solvent about 6%, and the polar stabilizer about 6%, the remainder being the dry granule. 5 Although methods for the deodorisation of thiophosphates by treatment with molecular iodine have been proposed, see for example NL-A-8104616 (Chem. Abs. 99, 40962r), JP-A-42003381 and FR-A-21 96751 , these do not include the use of a two-phase system involving polar and non-polar solvents as taught in the present invention. The treated thiophosphate is incorporated into a formulation suitable for application for biocidal io purposes. Any of the wide range of formulations developed for thiophosphates may be employed, using the formulating procedures and ingredients conventionally used and disclosed in the literature for this type of biocide. A major part of any such formulation is an inert diluent or carrier, which may take on any of a variety of forms, depending on the formulation. The inert diluent or carrier may thus be liquid or solid, for example, solvents, liquid carriers forming emulsions of the active ingredient, dusts, wettable powders, is porous granules, and microcapsules. The formulation may be a controlled-release formulation, and the active ingredient may be combined with other active ingredients for synergistic effects or for combining the biocidal activity of the thiophosphate with different types of biological activity, such as other types of biocidal activity, broadening of the pest control spectrum, and the inclusion of crop fertilizers or growth regulators. 20 The treated thiophosphates of the present invention are of particular interest for use in granular formulations. Any of the wide range of granular carriers known among those skilled in the art may be used. Examples include fuller's earth, attapulgite clay, bentonite clay, montmorillonite clay, kaolin, diatomaceous silicas, vermiculite, and perlite. The active ingredient is generally