Ioxynil

Hydroxybenzaldehyde has extensive use as an intermediate in the synthesis of a variety of agricultural chemicals. Halogenation of Nhydroxybenzaldehyde, followed by conversion to the oxime, and subsequent dehydration results in the formation of 3,5-dihalo-4-hydroxybenzonitrile (2). Both the dibromo- and dhodo-compounds are commercially important contact herbicides, hromoxynil [1689-84-5] (2) where X = Br, and ioxynil [1689-83-4]( where X = I respectively (74). Several hydrazone derivatives have also been shown to be active herbicides (70). 

After introducing recommended amounts of terbutrin and chlortoluron, wheat suffered more seriously from downy mildew. Monolinuron and simazin affected winter wheat similarly. Herbicides such as 2,4-MCPA, ioxynil, dicamba, and several others increased the amount of root rot damage to winter wheat on average by 60% when compared with the control crop. Treating grain crops using... 

Similarly, the selective herbicides, bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and ioxynil (3,5-diiodo-4-hydroxybenzonitrile) are degraded by soil bacteria to their corresponding amide products 3,5-dibromo-4-hydroxybenzamide (BrAM) and 3,5-diiodo-4-hydroxybenzamide (IAM) but are not further degraded to the corresponding acids. The identification of amidases or nitrilases able to effect these transformations, in a soil bacterium, would be of value as a bioremediation agent [48],... 

Nielsen, M.K.K., Holtze, M.S., Svensmark, B. and Juhler, R. (2007) Demonstrating formation of potentially persistent transformation products from the herbicides bromoxynil and ioxynil using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Pest Management Science, 63, 141-149. 

Recoveries in excess of 80% were achieved for 2,4-D, Dicamba, 3,6-dichloropicolinic acid, Dichloroprop, Picloram, 2,4,5-T Fenoprop, 2,3,6-TBA, Bromoxynil and Ioxynil (Table 9.22). 

Acid herbicides such as 2,4 dichlorophenoxy acetic acid, 2,4,5-trichlorophenoxy acetic acid, 3,6-dichloropicolinic acid and other types of herbicides such as Dicamba, Dichloroprop, Picloram, Fenoprop, 2,3,6-TBA, Bromoxynil and Ioxynil are widely used in agriculture and are often formulated as mixtures. They may also be mixed in the spray tank or used in sequence, so it is likely that residues of more than one of these compounds may be present in the soil. 

Many methods have been reported for the extraction of these compounds from soil. Khan [225] used acidified acetone followed by methylation with diazomethane for the simultaneous determination of 2,4-D, Dicamba and Mecoprop residues, as did Bache and Lisk [226] for Ioxynil. Abbott et al. [227] developed a method for MCPA, MCPB, 2,4-D Dichloroprop and 2,4,5-T in which dilute sulphuric acid and diethyl ether were used for extraction. Byast et al. [101] have shown that diethyl ether-chloroform-acetic acid is a suitable extractant for 2,4,5-T, 2,4-D, Dichloroprop and Dicamba [101] and saturated calcium hydroxide solution is efficient for Picloram [228] and 3,6-dichloropicolinic acid [229]. 

Herbicides. The use of herbicides (qv) based on iodine compounds has its main market in Western Europe. In Canada and the United States these compounds are used only to a small extent. The only significant iodine-containing herbicide is ioxynil [1689-85 4] (4,-hydroxy-3,5,-diiodobenzoic acid). This compound, often used in combination with other herbicides, is formulated for controlling many annual broad-leaved weeds, especially black-bindweed, knotgrass, mayweeds, and com marigold post-emergence in wheat, barley, oats, rye, and triticale (142). Annual consumption of iodine in relation to ioxynils is considered to be about 300—500 t (66). 

Bromoxynil, ioxynil residues Solvent partitioning Solvent partitioning Gas chromatography with ion-trap detector [71]... 

Bromoxynil, ioxynil Cereals Solvent extraction clean-up by solvent partitioning Perfluorination-GC with ion trap MS detection [142]... 

Creuzet, S., G. Ajlani, C. Vernotte, and C. Astier (1990). A new ioxynil-resistant mutant in Synechocystis PCC 6714 Hypothesis on the interaction of ioxynil with the D1 protein. Z. Naturforsch. Sect. CBiosci., 45 436 -40. 

Maenpaa, K.A., Sormunen, A.J. and Kukkonen, J.V.K. (2003) Bioaccumulation and toxicity of sediment associated herbicides (ioxynil, pendimethalin, and bentazone) in Lumbriculus variegatus (Oligochaeta) and Chironomus riparius (Insecta), Ecotoxicology and Environmental Safety 56 (3), 398-410. 

Ioxynil [1689-83-4] Ioxynil-octanoate [3681 17-0] Ioxynil-sodium salt [2961-62-8] Isopropalin [33820-53-0] Isoproturon [34123-59-6]... 

Apart from the sorbents already mentioned in connection with HPTLC pre-coated layers, a micro-crystalline cellulose has also been produced in an average particle size and a narrow particle size distribution suitable for HPTLC (9.). HPTLC pre-coated plates cellulose P 254 s (E. Merck, Darmstadt), composed of this microcrystalline cellulose, were used to separate Trevespan 6058. This is a mixture of the substances ioxynil (3,5-diiodo-4-hydroxy-benzo-nitrile), flurenol (9-hydroxyfluorenecarboxylic acid) and MCPA (2-methyl-4-chlorophenoxyacetic acid). For comparison purposes Trevespan 6038 was also separated on HPTLC pre-coated plates silica gel 60 F 254 (E. Merck, Darmstadt). 

Table V. Retention data (hRf values) for ioxynil, MCPA and flurenol on HPTLC pre-coated plates silica gel 60 (solvent system n-hexane/ethyl acetate/formic acid 40/60/0.5) and on HPTLC pre-coated plates cellulose (solvent system tert. butanol/water/25 ammonia 80/20/1)...

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