نتایج جستجو برای: triazines
تعداد نتایج: 1203 فیلتر نتایج به سال:
Various 2,4,6-trisubstituted 1,3,5-triazines were smoothly formed via TBHP-mediated direct oxidative coupling of amidine and methylarenes. This tandem oxidation-imination-cyclization transformation exhibits a straightforward protocol to prepare 1,3,5-triazines from easily available starting materials and green oxidants under metal-free conditions.
The scope of the [4 + 2] cycloaddition reactions of substituted 1,2,3-triazines, bearing noncomplementary substitution with electron-withdrawing groups at C4 and/or C6, is described. The studies define key electronic and steric effects of substituents impacting the reactivity, mode (C4/N1 vs C5/N2), and regioselectivity of the cycloaddition reactions of 1,2,3-triazines with amidines, enamines, ...
Derivatives of 6-chloro-5-methylthiopyrimidines provide potent inhibitors of the photosynthe tic electron flow, which act like Diuron on fluorescence induction kinetics and competitively displace it from its binding site. Structure-activity relationships show that, unlike triazines, ac tivities of 2or 4-alkylamino derivatives are restricted by steric hindrances. Decreases in inhibit ory acti...
The triazines are a group of chemically similar herbicides including atrazine, cyanazine, and propazine, primarily used to control broadleaf weeds. About 64 to 80 million lbs of atrazine alone are used each year in the United States, making it one of the two most widely used pesticides in the country. All triazines are somewhat persistent in water and mobile in soil. They are among the most fre...
Arylhydrazonomalononitriles 1a,b react with phenylhydrazine to yield amidrazones 2a,b that cyclize to give 2-aryl-5-phenylhydrazono-2,5-dihydro-[1,2,4]-triazine-6-carbonitriles 5a,b upon reaction with dimethylformamide dimethylacetal (DMFDMA). Refluxing 5a,b in glacial acetic acid resulted in the formation of the pyrazolo-1,2,4-triazines 6a,b. Compounds 6a,b were also formed upon treatment of 3...
Isolation of bacteria able to utilize s-triazines as the sole and limiting nitrogen sources for growth is described. Three strains of Pseudomonas (A, D, and F) and two strains of Klebsiella pneumoniae (90 and 99) were examined. Strains D and F utilized N-ethylammelide, N-isopropylammelide, ammeline, ammelide, cyanuric acid, and ammonium ion as nitrogen sources. Strain A utilized melamine, ammel...
This study was undertaken to find a simple and accurate structural parameters for the quantita tive description of inhibitory potency of 2-azido-s-triazines in Hill reaction and to gain more information about the mechanism of inhibition on molecular level. A very good correlation (r = 0.946) was obtained between the plS(> values (the negative logarithm of the molar concentra tion that causes ...
ring cleavage occurred when 1,2,4-triazino-1,2,4-triazines (3), (4) and (5) were treated with concentrated hydrochloric acid to yield n-substituted triazines (7) and (8). these confirm the given configuration assigned to the isomeric triazinotriazines. 6-methyl-2-phenyl-7h-oxazolo [3,2-b][1,2,4]-triazin-7-one (9) underwent ring cleavage on treatment with sodium alkoxide to afford 3-alkoxy-1,2,4...
Polyaniline/Fe3 O4 magnetic nanoparticles were synthesized and employed as a sorbent for the magnetic solid phase extraction (MSPE) of seven triazine herbicides from environmental water samples. The properties of the prepared magnetic sorbent were characterized using field emission-scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetome...
The aza-Diels-Alder cycloaddition of 1,2,4-triazines with alkynes offers a rapid and convenient method for the synthesis of highly substituted pyridines, but often requires harsh conditions and long reaction times. The present study offers a solution to these limitations by use of a temporary tether established by a Lewis acid-base complexation of in situ generated alkynylboranes and triazines ...
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