Atropisomerism, Chiral Centre and Activity of Metolachlor

Moser, Heinz; Rihs, G.; Sauter, Hanspeter; Bohner, Barbara

doi:10.1016/b978-0-08-029222-9.50047-0

Cited by 24 publications

(39 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In addition, the methyl group at the C‐chiral centre of 18 can further lower the reactivity of the molecule by hindering the reaction centre. The herbicidal activity of 18 was found to be influenced mainly by the chiral centre rather than the chiral axis and the S ‐enantiomers were the most active herbicides 20. Similarly the S configuration on the asymmetrically substituted carbon atom in dimethenamid, another commercially available herbicide, results in the herbicidally much more active forms 21…”

Section: Resultsmentioning

confidence: 99%

Alkylating reactivity and herbicidal activity of chloroacetamides

Jablonkai

2003

Pest Management Science

View full text Add to dashboard Cite

The relationship between S- and N-alkylating reactivity and herbicidal activity within a series of chloroacetamides, including several commercial herbicides and newly synthesised analogues was studied. The S-alkylating reactivity of selected chloroacetamides, as well as those of atrazine and chlorfenprop-methyl, was determined by in vitro GSH conjugation at a ratio of GSH to alkylating agent of 25:1. A spectrophotometric reaction using 4-(4-nitrobenzyl)pyridine was used to characterise the N-alkylating reactivity of the chemicals. Our results indicate that a reduced level of N-alkylating reactivity correlates with an improved herbicidal efficacy at a practical rate. However, the phytoxicity of the molecules is not simply dependent on chemical reactivities, but strictly related to the molecular structure, indicating that lipophilicity, uptake, mobility and induction of detoxifying enzymes may also be decisive factors in the mode of action.

show abstract

Section: Resultsmentioning

confidence: 99%

Alkylating reactivity and herbicidal activity of chloroacetamides

Jablonkai

2003

Pest Management Science

View full text Add to dashboard Cite

show abstract

“…O produto formulado DUAL ® é formado por dois isômeros R e dois S de metolachlor, que estão presentes em proporções semelhantes no herbicida. Os isômeros S apresentam maior atividade herbicida do que os isômeros R (Moser et al, 1982). Com o conhecimento dessa propriedade, foi desenvolvido novo sistema catalítico, que produziu uma formulação enriquecida (>80%) com os isômeros S, a qual foi denominada S-metolachlor, originando o produto formulado DUAL GOLD ® (Blaser & Spindler, 1997;Spindler et al, 1998).…”

Section: Introductionunclassified

Persistência do herbicida S-metolachlor associado ao glyphosate ou paraquat em plantio direto

Nunes

Vidal

2008

Planta daninha

View full text Add to dashboard Cite

RESUMO -A associação de herbicidas dessecantes com efeito residual é comum entre os agricultores no manejo das áreas sob semeadura direta. Essa prática permite a dessecação da cultura de inverno a ser utilizada como cobertura morta e, também, evita a reinfestação por plantas daninhas na cultura de verão durante parte de seu ciclo. O objetivo do presente trabalho foi determinar a persistência do herbicida residual S-metolachlor, quando associado com os herbicidas dessecantes glyphosate ou paraquat, aplicados sobre cobertura vegetal. O trabalho foi realizado a campo na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul (EEA/UFRGS) e em câmara de crescimento da Faculdade de Agronomia da UFRGS, sob Argissolo Vermelho distrófico típico, contendo 28% de argila. O delineamento experimental foi de blocos casualizados, com quatro repetições, sendo os tratamentos distribuídos em parcelas subdivididas. Nas parcelas principais, foram alocados os herbicidas dessecantes paraquat (600 g ha -1 ) ou glyphosate (720 g ha -1 ) e, nas subparcelas, o herbicida residual S-metolachlor (2.800 g ha -1 ) associado ou aplicado seqüencialmente aos herbicidas dessecantes, além de uma testemunha contendo apenas herbicida dessecante, sem aplicação do herbicida residual. A persistência do S-metolachlor é maior na presença do paraquat do que na do glyphosate. Não há diferença entre aplicação simultânea e seqüencial dos herbicidas dessecantes e residuais.Palavras-chave: bioensaio, cinética de dissipação, meia-vida, residual.ABSTRACT -Non-selective and residual herbicides are commonly associated by farmers to manage no-tillage areas. This practice allows controlling the winter crop to be used as cover crop and to avoid weed reinfestation during part of the summer crop cycle. The objective of this work was to determine the persistence of the residual herbicide S metolachlor when associated to the nonselective herbicides paraquat and glyphosate. The work was carried out under field conditions at the Estação Experimental Agrônomica of the Universidade Federal do Rio Grande do Sul (EEA/ UFRGS), and in a growth chamber of the Faculdade de Agronomia of the UFRGS under typical Dystrophic Red Argisol composed by 28% clay. The experiment was arranged in a randomized block design with four replications, with the treatments distributed in split plots .The non-selective herbicides (paraquat, 600 g ha -1 or glyphosate 720 g ha -1 ) were applied in the main plots, and the residual herbicide S-metolachlor (2.800 g ha -1 ) in the sub plots, associated or sequentially applied with the non-selective herbicides, plus one control with only non-selective herbicides being applied. The persistence of S-metolachlor is higher in the presence of paraquat when compared to glyphosate. No difference was found between simultaneous and sequential applications of the non-selective and residual herbicides.

show abstract

“…1). In 1982, Moser et al 3 reported on the synthesis and separation of the resolved isomers of metolachlor, showing that the S isomers had at least 20‐fold greater pre‐emergence activity on seven grasses and three broadleaf weeds than the R isomers. These results suggest that 95% of the herbicidal activity of metolachlor is due to the S isomers.…”

Section: Introductionmentioning

confidence: 99%

“…S ‐Metolachlor is approximately 88% S isomer and 12% R isomer 3. This enrichment of the S isomer is accomplished through a selective synthetic manufacturing process 3 .…”

Section: Introductionmentioning

confidence: 99%

Soil dissipation and biological activity of metolachlor and S‐metolachlor in five soils

Shaner

Brunk

Belles

et al. 2006

Pest Management Science

View full text Add to dashboard Cite

The resolved isomer of metolachlor, S-metolachlor, was registered in 1997. New formulations based primarily on the S-metolachlor isomer are more active on a gram for gram metolachlor basis than formulations based on a racemic mixture of metolachlor containing a 50:50 ratio of the R and S isomers. The labelled use rates of S-metolachlor-based products were reduced by 35% to give equivalent weed control to metolachlor. However, several companies have recently registered new metolachlor formulations with the same recommended use rates for weed control as S-metolachlor. This research was done to compare the soil behaviour and the biological activity of metolachlor and S-metolachlor in different soils under greenhouse and field conditions. Although K(d) ranged from 1.6 to 6.9 across the five soils, there were no differences in the binding of metolachlor and S-metolachlor to soil or in the rate of soil solution dissipation in a given soil. However, both greenhouse and field studies showed that S-metolachlor was 1.4-3-fold more active than metolachlor against Echinochloa crus-galli (L.) Beauv. in five different soils and that S-metolachlor was more active than metolachlor in three Colorado field locations. When the rates of metolachlor and S-metolachlor were adjusted for S isomer concentrations in the formulations, there were no differences between the formulations in field, greenhouse or bioassay studies. Thus herbicidal activity is due to the S isomers, with the R isomers being largely inactive.

show abstract

Atropisomerism, Chiral Centre and Activity of Metolachlor

Cited by 24 publications

References 3 publications

Alkylating reactivity and herbicidal activity of chloroacetamides

Alkylating reactivity and herbicidal activity of chloroacetamides

Persistência do herbicida S-metolachlor associado ao glyphosate ou paraquat em plantio direto

Soil dissipation and biological activity of metolachlor and S‐metolachlor in five soils

Contact Info

Product

Resources

About