The dye-sensitized photolysis of aerated aqueous solutions of terbacil (3-tert-5-chloro-6-methyluracil, I) exposed to solar irradiation was investigated under different reaction conditions. After 2 h of exposure to sunlight, in the presence of methylene blue (3 ppm) or riboflavin (10 ppm), the major photodegradation product in the pH range of 3.0-9.2 was 3-tert-butyl-5-acetyl-5-hydroxyhydantoin (11). In alkaline reaction mixtures (pH 8.0 or 9.2), this product undergoes deacylation, giving 3-tert-5-hydroxyhydantoin (111). In experiments carried out under neutral or acidic conditions (PH 6.8 or 3.0) with riboflavin, two additional products were isolated a mono-N-dealkylated terbacil dimer (IV) and a nonidentified water-insoluble product (V). The structures of 11,111, and IV were determined by using proton and carbon-13 nuclear magnetic resonance, infrared, ultraviolet, and mass spectroscopy.Terbacil (3-tert-butyl-5-chloro-6-methyluracil,
The efficiency of a photo‐oxidation procedure for the detoxication of water containing herbicides of the uracil group was tested by bioassay. Treated herbicide solutions were checked for their inhibiting effect on germination and photosynthesis in sorghum (Sorghum bicolor). The treated solutions, and the main photodegradation products of bromacil and terbacil did not inhibit significantly either germination or seedling development at concentrations of up to 200 and 10 mg litre−1, respectively. Preliminary tests with industrial waste effluents containing added uracil compounds showed that these compounds were rendered non‐phytotoxic by the photo‐oxidation procedure.
The stithility o/' soiiir diluted eriiiilsjfiublr coiiceritratc fbrinirlutioris iri c k u r liyuiri ,f'erti/izer.s, us uijkcted by the riuture urn2 coiict'ritrutioti of' the salt solirt intis, IVUS chrcked by u stutic test. The tinw-itidLicei! c/iuri(jes iri the coricentrutioii of the dispersed pliuse w c w estimuted bji uisirul ohsrrcutioris uiid turbidity rii~~ti~~irenieiit.~, For eucli ,fiirriiirlatiori u specific relntioriship hetweeii the electricul coriducticitj. of all the jkrt ilixr solirtioris c u d tlie emirlsiori stubilit!. M'NS joirnri. This MWS rvlid jiw u pH runye hrtweeri 4.66.3: in crlkrilirie conrlitioris t l i e emulsion strrhilitji wus reluticrly l o w r . A critictil electricul coiiducticity runye, uhocr which irreversible iiestubilizutiori occwrred, wus ohsi~rrwi .fbr tmcli jbrmulutiori: 100-120 d S 111-' ./Or fknuniiphos, 60-70 dS m--' fbr nietoluchlor, 30-50 ilS 111 -' ,fiw clilorpyrlfbs, und uhout 45 dS t i i -' for S-ethyl iiiprop),lthiocurburrliate ( E P T C ) .The correlutiori obserwd bet,veeti thr emirision stribilitj> mid tlie electric.rr1 coricluctii~ity could he user1 iri u simple uiid rtipid qiiulitutiiv test to estiriiate the pliysictil computibility hetweeri rmuls$uhle coriceritrute formulrrtioiis uwd liyir id j i r t ilizers.before use, allows for versatility in the preparation of the mixtures and avoids eventual problems arising from their joint tora age.^ One of the main requirements for pesticide--fertilizer combinations is to form homogeneous and stable spray mixtures, in order to provide a uniform distribution and avoid blockage of the application equipment.' However, pesticide formulations which are manufactured to form stable suspensions or emulsions upon dilution with water may behave differently when mixed with liquid fertilizers.By diluting emulsifiable concentrate (EC) formulations, oil-in-water emulsions are obtained. Since disperse systems are thermodynamically unstable, most ECs contain non-ionic and anionic stabilizers, which stabilize them by steric and charge stabilization, respectively.The stability aspects of pesticide formulations of the dispersion type are very complex, and were recently discussed in a comprehensive review." In general terms: the stability of a dispersed system depends on the relative magnitude of the potential energy of attraction and that of repulsion of the dispcrsed particles.The most commonly used liquid fertilizers are actually salt solutions. which may contain ions. ion pairs, or undissociated salt molecules. The well-known effect of destabilization of dispersed systems by electrolytes involves the decrease of the surface potential of the particles and the compression of the double layer, resulting in the decrease in the repulsion energy between the particles.' In addition, some components of the fertilizer solutions may favourably compete with the hydrophilic moiety of the stabilizing, surface-active agents for water molecules. decreasing the thickness of the interfacial film.4The main processes involved in the breakdown of emulsions...
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