Showing papers on "Pyrazole published in 1971"
TL;DR: The data indicate that ethanol shares certain characteristics with other agents which produce a type 2 spectrum and the interaction of pyrazole with hepatic microsomes should be noted when it is used to study in vivo metabolism of ethanol.
57 citations
TL;DR: In this paper, a new class of compounds, the N-(trimethylsilyl)pyrazoles, has been prepared, which undergo temperature-dependent NMR spectral changes with the 3,5-substituents becoming equivalent at high temperatures.
39 citations
Journal Article•
TL;DR: Alcohol dehydrogenases of yeast and mouse liver differ in their relative sensitivity to inhibition by pyrazole and 4-brompyrazole, which results in mice liver alcohol dehydrogenase is strongly inhibited by both compounds.
Abstract: Alcohol dehydrogenases of yeast and mouse liver differ in their relative sensitivity to inhibition by pyrazole and 4-brompyrazole. Yeast alcohol dehydrogenase is relatively insensitive to 4-brompyrazole. The K1 for pyrazole is 1.1 x 10-5 M; for 4-brompyrazole, 1.1 x 10-3 M. Both inhibit competitively with ethanol. Yeast alcohol dehydrogenase can be used for assay of blood alcohol in pyrazole-treated mice. Mouse liver alcohol dehydrogenase is strongly inhibited by both compounds. The K1 for pyrazole is 8 x 10-7 M, competitive with ethanol, and for 4-brompyrazole, 3 x 10-7 M, competitive or mixed type inhibition. Pyrazole has a half-life of about 10 hours and 4-brompyrazole about three hours in mice, as estimated from alcohol elimination rates. The LD50 after single i.p. injections of pyrazole in mice is 7.9 mmol/kg; for 4-brompyrazole, 2.5 mmol/kg. Thus the ratio of efficacy to toxicity is about the same for the two compounds, but 4-brompyrazole has a shorter duration of action.
31 citations
TL;DR: In this article, electron paramagnetic resonance spectra have been recorded for some compounds of the type Mn(ligand)4- (anion)2, with pyrazole and 3(5)-methyl pyrazoles as the ligands, and Cl−, Br−, I−, and NO3− as the anions.
27 citations
TL;DR: 2,3-Dihydro-1H-imidazo[1,2-b]pyrazole has been shown to inhibit DNA synthesis in animal cells growing in culture, but has no effect on bacterial cells.
26 citations
TL;DR: In this article, pyrazole and 3-methylpyrazole complexes of the type Cu X 2 L 4 (X = Cl, Br, 1 2 So 4, NO 3 ) are formed.
21 citations
TL;DR: Triazenopyrazoles having both the ester and the amide groups increased the average survival time in the standard mouse L-1210 leukemia assay and in some of these tests, increases in lifespan of 60-120% were observed.
20 citations
TL;DR: Pyrazole has a rapid onset of action in vivo and has an effective half life for inhibition of NADH dependent aldehyde reduction in rat liver of about 76 hr following a dose of 360 mg × kg−1 intraperitoneally.
20 citations
TL;DR: The effects produced by four shift reagents on the proton magnetic resonance spectra of 1-methylimidazole and seven pyrazole derivatives have been determined as mentioned in this paper.
Abstract: On a determine l'effet produit par quatre reactifs de deplacement sur les signaux de sept derives du pyrazole et sur ceux du methyl- 1 imidazole. Ces effets sont discutes en fonction de leur utilite pour differencier des structures isomeres.
The effects produced by four shift reagents on the proton magnetic resonance spectra of 1-methylimidazole and seven pyrazole derivatives have been determined. These results are discussed in the light of their usefulness in differentiating between structural isomers.
19 citations
TL;DR: Cyclic hemiaminal formation in solid X-unsubstituted azole aldehydes seems to be a general phenomenon when stabilization factors and position of substitution are favorable.
Abstract: Cyclic hemiaminal formation in solid X-unsubstituted azole aldehydes seems to be a general phenomenon when stabilization factors and position of substitution are favourable. Previously reported for 5- substituted 1,2,4-triazole-3-carbaldehydes and benzimidazole-2- carbaldehyde, it has been found to occur also in some previously undescribed aldehydes of pyrazole, imidazole, 3H-imidazo[4,5- b]pyridine, 3H-imidazo[4,5-c]pyridine, and purine. In purine-8- carbaldehyde the hemiaminal may be accompanied by the aldehyde hydrate. P.m.r. studies of the dimers, and of the dipiperidino cyclic aminals derived from them, indicate that in some cases more than one isomeric form is present.
18 citations
TL;DR: In this paper, 4-Bis(trimethylsilyl)pyrazole (1) and 4-TrimethylSilyl-pyrazol (2) are nitrosated with sodium nitrite in the presence of trifluoroacetic acid to form 4-nitrosopyrazole.
Abstract: 3(5).4-Bis-trimethylsilyl-pyrazol (1) und 4-Trimethylsilyl-pyrazol (2) werden mit Natriumnitrit in Gegenwart von Trifluoressigsaure zu 4-Nitroso-pyrazol (3) nitrosiert. Ebenso bildet sich 3 aus 1 und Athylnitrit/Trifluoressigsaure bzw. Isoamylnitrit//Ameisensaure. Mit Isoamylnitrit allein werden bei hoherer Temperatur 2 zu 3, 1 zu 3(5)-Nitroso-4-trimethylsilyl-pyrazol (5) und 3 sowie 3(5)-Trimethylsilyl-pyrazol (4) zu 3(5)-Nitroso-pyrazol (6) und 3 umgesetzt. Die Nitrosopyrazole 3, 5 und 6 lassen sich leicht zu den entsprechenden Nitroverbindungen oxydieren. — Die saure Hydrolyse von 5 und von 3(5)-Nitro-4-trimethylsilyl-pyrazol (7) fuhrt zu 6 bzw. zu 3(5)-Nitro-pyrazol (8). — Trimethylsilyl-benzol und p-Trimethylsilyl-toluol ergeben mit Alkylnitrit//Trifluoressigsaure Nitrosobenzol bzw. p-Nitrosotoluol.
C-Nitrosation via Silyl Derivatives
3(5).4-Bis(trimethylsilyl)pyrazole (1) and 4-(trimethylsilyl)pyrazole (2) are nitrosated with sodium nitrite in the presence of trifluoroacetic acid to form 4-nitrosopyrazole (3). The latter compound is also obtained by treatment of 1 with ethyl nitrite//trifluoroacetic acid or isoamyl nitrite//formic acid. With isoamyl nitrite alone at elevated temperatures 2 gives 3 and 1 gives 3(5)-nitroso-4-(trimethylsilyl)pyrazole (5) and 3. Under the same conditions 3(5)-(trimethylsilyl)pyrazole (4) yields 3(5)-nitrosopyrazole (6) and 3. The nitrosopyrazoles 3, 5 and 6 can be readily oxidized to the corresponding nitro compounds. — Acid hydrolysis of 5 and 3(5)-nitro-4-(trimethylsilyl)pyrazole (7) yields 6 and 3(5)-nitropyrazole (8), respectively. – Trimethylsilylbenzene and p-(trimethylsilyl)toluene react with alkyl nitrite//trifluoroacetic acid to form nitrosobenzene and p-nitrosotoluene, respectively.
TL;DR: In this article, the hyperfine structure of a number of lines in the microwave spectra of 1-D and 4-D pyrazole has been measured and analysed. And the results have been compared with field gradient tensors calculated from molecular orbital wave functions.
TL;DR: The mass spectra of monocyclic 1,2,4-triazines were investigated in this paper, showing that loss of nitrogen from the molecular ions is a relatively unimportant feature.
Abstract: The mass spectra of monocyclic 1,2,4-triazines and 1,2,4-triazines fused to a pyrazole ring through a bridgehead nitrogen have been investigated: fragmentation pathways were elucidated by the use of metastable ions and high resolution mass measurements. The spectra of the monocyclic 1,2,4-triazines indicate that loss of nitrogen from the molecular ions is a relatively unimportant feature. The decomposition modes of the bicyclic pyrazolo[3,2-c]-as-triazines are sensitive to the nature of the substituent in the triazine ring.
TL;DR: Minimally effective doses of pyrazole and 3‐methylpyrazole, a non‐inhibitor of LADH, when administered before ethanol resulted in an increased behavioural depression, probably not caused by inhibition of L ADH but rather by an increase in the direct depressant action of either one or both of the compounds.
Abstract: 1. Interactions of pyrazole and ethanol were studied in three laboratory test procedures. They included sleeping time in mice, rotor rod balance in rats and lever pressing behaviour of rats.
2. Equimolar concentrations of pyrazole and 3-methylpyrazole were compared for effects on enhancement of ethanol's activity on rotor rod holding time of rats.
3. Minimally effective doses of pyrazole, the LADH inhibitor, and 3-methylpyrazole, a non-inhibitor of LADH, when administered before ethanol, resulted in an increased behavioural depression. These interaction effects are probably not caused by inhibition of LADH but rather by an increase in the direct depressant action of either one or both of the compounds.
TL;DR: In this paper, the pyrazoles were obtained in the presence of 2,5-diphenyltetrazole and 5-cyano- or carbamoyl-pyrazoles in good yields.
Abstract: Cyanoacetylene and chlorocyanoacetylene and the corresponding propiolamides reacted with diazomethane to give exclusively 5-cyano- or-carbamoyl-pyrazoles in good yields. Although cyanoacetylenes did not react with N-phenylsydnone in refluxing benzene, in chlorobenzene at ca. 110° the expected pyrazoles were obtained. Irradiation of 2,5-diphenyltetrazole in the presence of cyanoacetylene afforded 1,3-diphenylpyrazole-5-carbonitrile. The adducts formed from cyanoacetylenes and hydrazines could not be cyclised.
TL;DR: Gas phase pyrolysis of tetrazolo[1,5-a]pyrimidines leads via ring contraction to 1-cyanopyra zoles, then at higher energy to N2loss and formation of unsaturated nitriles as mentioned in this paper.
TL;DR: In this article, a continued structural modification study of the antimalarial compounds 3-piperonylsydnone and 2,4-diamino-5 piperonylpyrimidine was conducted.
Patent•
19 May 1971TL;DR: In this paper, the 1-(substituted-hydrocarbyl)-di- and trihalopyrazoles have been synthesized, which possess herbicidal and plant growth regulatory activity.
Abstract: Certain new 1-(substituted-hydrocarbyl)-di- and trihalopyrazoles have been synthesized. They possess herbicidal and plant growth regulatory activity. The hydrocarbyl group, i.e., alkylene or alkenylene group at the 1-nitrogen of the pyrazole nucleus has either a carboxyl group, an hydroxymethyl group, an hydroxymethyl lower-alkanoate group, a carboxylic lower-alkyl ester group, a cyano group, or a carboxylic amide group. The new compounds are prepared and isolated by conventional chemical reactions and procedures. An improved reaction for making the new carboxylic acids is described. Weed control methods and compositions for herbicidal use are also described.
TL;DR: 5-Aminoimidazole and some 1-substituted derivatives, including the naturally occurring riboside and ribotide, have been shown to form the corresponding 5-amino-azole-4-carboxylic acids in 40–50% yields when heated with aqueous potassium hydrogen carbonate.
Abstract: 5-Aminoimidazole and some 1-substituted derivatives, including the naturally occurring riboside and ribotide, have been shown to form the corresponding 5-aminoimidazole-4-carboxylic acids in 40–50% yields when heated with aqueous potassium hydrogen carbonate. Similar reactions occur with unsubstituted and 1-substituted 5-amino-pyrazoles and, to a lesser extent, with 5-amino-1,2,3-triazole. In addition to the 5-amino-azole-4-carboxylic acids, the reaction mixtures contained unchanged 5-amino-azoles. Similar mixtures of 5-amino-azole and 5-amino-azole-4-carboxylic acid were obtained when several 5-amino-imidazole, -pyrazole, and -1,2,3-triazole-4-carboxylic acids were heated with aqueous potassium hydrogen carbonate.
TL;DR: In this article, a procedure for monitoring the reactivity of a substrate towards bromine in aqueous bromide solutions, as a function of extent of reaction, by following the changes of electrode potential with time in the intervals between successive periods of electrolysis, was described.
Abstract: A procedure is described for monitoring the reactivity of a substrate towards bromine in aqueous bromide solutions, as a function of extent of reaction, by following the changes of electrode potential with time in the intervals between successive periods of electrolysis. The title compounds show 1 : 1 stoicheiometry with substitution in the 4-position. The observed rate behaviour may be understood in terms of direct attack by molecular bromine on the neutral substrate molecules, rate coefficients for dilute aqueous solution at 25°C being: k20(Br2+pyrazole) = 3.8x105 dm3 mol-1 s-1, kH/kD = 1.39; k20(Br2+1.methylpyrazole) = 8.0x105 dm3 mol-1 s-1; k20(Br2+3,5-dimethylpyrazole) = 1.4x109 dm3 mol-1 s-1, kH/kD = 1.08 Values of pKa(pyrazole-H+) = 2.58 and pKa(3,5-dimethylpyrazole-H+) = 4.11 were determined by potentiometric titration methods.
TL;DR: The lability of the co-ordinated pyrazole is attributed to the effect of the ‘hard' co-coordinated nitrogen atoms as discussed by the authors, which is the main reason for the difficulty of co-composition.
Abstract: Reaction of BrM(CO)5 or M2(CO)10(M = Mn or Re) with potassium dihydrobis(pyrazolylato)borate affords the crystallline complexes [{H2B(N2C3H3)2}M(CO)3(pyrazole)]. Reaction with phosphines or phosphites (L) leads to the rapid formation of the disubstitued compounds [{H2B(N2C3H3)2}M(CO)2L2]; in the case of the phosphines the ligands (L) have a relative cis-configuration, whereas, with phosphites the corresponding trans-complexes are obtained. The lability of the co-ordinated pyrazole is attributed to the effect of the ‘hard’ co-ordinated pyrazole nitrogen atoms. Tetra-alkylammonium halides react with [{H2B(N2C3H3)2}M(CO)3(prazole)] to form the stable anions [{H2B(N2C3H3)2}M(CO)3X]–(X = Br or l).
TL;DR: In this article, the nucleophilic substitution mechanism of the Grunanger pyrazole synthesis was confirmed and 3-Glycosyl-pyrazoles can also be prepared from aldehydo-sugar hydrazonoyl bromides by 1,3-dipolar cyclo-addition.
Abstract: The reaction of an aldehydo-sugar hydrazonoyl bromide with ethynylmagnesium bromide led mainly to an α-ethynyl-hydrazone whose cyclisation to a pyrazole is catalysed by bases. Thus the nucleophilic substitution – nucleophilic cyclisation mechanism of the Grunangerpyrazole synthesis is confirmed. 3-Glycosyl-pyrazoles can also be prepared from aldehydo-sugar hydrazonoyl bromides by 1,3-dipolar cyclo-addition. All these reactions take place without change in the configuration of the initial aldehydo-sugar.
TL;DR: In this article, an X-ray crystal structure determination showed that the product of the reaction of methyl phenylpropiolate with 1-hydrazino-3-methylisoquinoline is 5-hydroxy-3phenyl-1-(3methyl-1-isoquinolyl)pyrazole.
Abstract: Die rontgenographische Strukturbestimmung weist das Produkt aus Phenylpropiolsauremethylester und 1-Hydrazino-3-methyl-isochinolin (1b) als 5-Hydroxy-3-phenyl-1-[3-methylisochinolyl-(1)]-pyrazol aus. Die Kristalleinheit enthalt zwei unabhangige Molekule.
The Crystal Structure of 5-Hydroxy-3-phenyl-1-(3-methyl-1-isoquinolyl)pyrazole
An X-ray crystal structure determination shows that the product of the reaction of methyl phenylpropiolate with 1-hydrazino-3-methylisoquinoline is 5-hydroxy-3-phenyl-1-(3-methyl-1-isoquinolyl)pyrazole. The crystal asymmetric unit contains two independent molecules.
TL;DR: Mossbauer spectra are reported and discussed for a number of compounds of formula Fe(ligand)6(anion)2, with pyrazole, 3(5)-methylpyrazole and imidazole as ligands, and ClO4−, Br− and I− as anions.
Abstract: Mossbauer spectra are reported and discussed for a number of compounds of formula Fe(ligand)6(anion)2, with pyrazole, 3(5)-methylpyrazole, imidazole, N-methylimidazole and N-n- butylimidazole as ligands, and ClO4−, Br− and I− as anions
The values found for the isomer shift (δ) and the quadrupole splitting (ΔEq) are in agreement with high-spin iron(II) in a distorted octahedral coordination
The magnitude of δ, being 132 ± 002 mm/s, in these compounds is rather small and occurs at the lower site of the range usually found for octahedral iron(II)
For closely resembling compounds a relation is found between ΔEq and the value of the magnetic moment
The author is indebted to Drs D W Engelfriet, D Knetch and Ir A M van der Kraan for assistance with the measurements, and to Dr A M van der Kraan for assistance with the measurements, and to Dr W L Groeneveld for his interest in this study
TL;DR: In this paper, photolysis of the methyldiazepine (5a) led directly to pyrazole (7) whereas the ethoxycarbonyl- and acetyl-diazepines (5b) and (5c) gave cycloadducts (6b)
Abstract: Photolysis of the methyldiazepine (5a) led directly to the pyrazole (7) whereas the ethoxycarbonyl- and acetyl-diazepines (5b) and (5c) gave cycloadducts (6b) and (6c); thermolysis of the diazepines (5) or the diaza[3,2,0]bicycloheptadienes (6) produced mainly ylides (8) and small amounts of 2,4,6-triphenylpyridine (9), except for (5a) which yielded (9) only.
TL;DR: In this paper, the authors explored the scope of the ring contraction of pyridazinone to pyrazole, 2-phenyl-4-chloro-5-methylthio-3 (2H)-pyrinone (IIIa) with 4 and 5 substituents other than chlorine.
Abstract: In order to explore the scope of the ring contraction of pyridazinone to pyrazole, 2-phenyl-3 (2H)-pyridazinones (IIIa-f) and (IVa-e) having 4 and 5 substituents other than chlorine were prepared and examined their behavior against sodium hydroxide. Amongthem, (Ma, b) and (IVa, b, e) undergothe ring contraction to afford the corresponding pyrazole carboxylic acid, (V), (VII), and (VIII). From available data, substituent effects and mechanisms for these ring contractions were discussed.In the course of this study, an unusual displacement reaction was observed in the reaction of 2-phenyl-4-chloro-5-methylthio-3 (2H)-pyridazinone (IIIa) with sodium hydroxide and sodium ethoxide.