Produktpräferenzanalyse

Gutsche, Jens

doi:10.3790/978-3-428-48473-7

Cited by 67 publications

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“…Following Gutsche (ref c, page 130), we use the term “ketocalixarenes” to designate calixarene analogues possessing phenol rings connected by carbonyl groups.…”

Section: Referencesmentioning

confidence: 99%

“…The conformation of p-tert -butylcalix[4]arene ( 1 ) is usually discussed in terms of four basic conformations: cone, partial cone, 1,2-alternate, and 1,3-alternate (Figure ) . Replacement of the hydroxyl protons by bulky groups (e.g., propyls) sterically hinders the rotation through the annulus of the rings, and the four forms are available as stable atropisomers on the laboratory time scale .…”

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A Conformationally Flexible Tetrahydroxycalix[4]arene Adopting the Unusual 1,3-Alternate Conformation

et al. 2003

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“…Following Gutsche (ref c, page 130), we use the term “ketocalixarenes” to designate calixarene analogues possessing phenol rings connected by carbonyl groups.…”

Section: Referencesmentioning

confidence: 99%

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confidence: 99%

A Conformationally Flexible Tetrahydroxycalix[4]arene Adopting the Unusual 1,3-Alternate Conformation

et al. 2003

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“…A technology that positively changes the agrochemical and agrophysical properties of soils has been introduced to farms with small and large land areas operating in the conditions of typical gray, barren and meadow-alluvial soils of Uzbekistan [5]. That is, it increases the amount of humus in the soil by 0.045-0.056%, the amount of total nitrogen by 0.030-0.042%, the yield of cotton by 10-12% (32-36 tons/ha), and the yield of winter wheat by 15-20% (50-55 tons/ha) [6]. short-row rotation was applied.…”

Section: Introductionmentioning

confidence: 99%

Effect of using repeated and siderate crops on soil fertility, yield of cotton varieties, and technological quality indicators of cotton fiber in short rotation cropping systems

Iminov,

Ulugov,

Kholturaev

et al. 2023

E3S Web of Conf.

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In the 1:1 (cotton:grain) system of short-rotation, soybean, bean, mung bean crops were harvested as a repeat crop after winter wheat. Their stem crop and mixed siderate crops (perco, oats, green peas) were planted in the second half of August, and the blue mass crop grown in October-November was harvested for livestock. The lower 15-20 cm part of the stem was plowed under the plow as a blue manure, at the end of one rotation, the amount of organic carbon in the soil increased by 0.041-0.073%, and the total nitrogen content by 0.012-0.016% compared to the initial values. The highest rate of dry mass accumulation of cotton was observed when using short-row rotation 1:1, winter wheat + mixed siderate crops (perco, oat, green pea):cotton system. The dry mass of the leaves of the Navroz variety of cotton was 22.6 g, the dry mass of the stem was 33.4 g, the dry mass of the bolls was 18.5 g, and the dry mass of the cotton was 48.0 g. The total dry mass of 1 plant was equal to 122.5 g. In the 1:1 (cotton:grain) system of short-rotation, when cotton was grown as a repeat crop after legume-cereal (soybean, mung bean) and mixed siderate (perco, oat, green pea) crops, it provided a higher and better quality cotton yield. Cotton yield was 3.2-5.8 tons/ha, fiber output was 1.0-1.5 percent, and 1000 seed mass was 9.0-11.0 g/ha. Besides, the length of the fiber was found to be higher by 1.4-2.0 mm.

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“…In most cases, functionalization of the calix scaffold with specific functional groups is desirable. Although a multitude of synthetic methods are available for the modification of the aryl groups of the calixarenes, only few have been reported allowing the functionalization of their methylene groups . Calixarenes incorporating carbonyl groups at the bridges (ketocalixarenes) may serve as starting materials for the preparation of such systems .…”

Section: Introductionmentioning

confidence: 99%

Isotopic Perturbation of the Conformational Equilibrium in Methylene-Functionalized Calixarenes

Kuno

Biali

2008

J. Org. Chem.

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The 400 MHz 1H NMR spectrum of the tetramethoxycalixarene 2 (possessing hydroxyl groups at the bridges) in commercial acetone-d6 displays five signals (an isotopic multiplet) for a pair of methoxy groups. Inspection of the X-ray structures of 2 and its isomer 3 indicates that in the adopted 1,3-alternate conformation, the methoxy groups intramolecularly hydrogen bonded to neighboring OH groups are oriented "in" (pointing toward the cavity). Upon dissolution of 2 in acetone-d6, none, some, or all of the OH protons exchange with the deuterium atoms present in the residual water of the solvent. Several species (mutually relating as isotopomers and isotopologues) differing in the number and positions of the deuterated hydroxyl groups are possible for 2. In three of these species, the "in"-"out"/"out"-"in" conformational equilibrium of a pair of methoxy groups is nondegenerate. The four external lines of the apparent multiplet are ascribed to a single- and double-isotopic perturbation of the "in"-"out" conformational equilibrium of a pair of methoxy groups. On the basis of the assignment of the signals to the individual species and their statistical distribution, the intensities of the components of the isotopic multiplet obtained at different isotopic enrichments of the hydroxyl groups could be simulated. A sample of 2 55% deuterated at the hydroxyl groups in CDCl3 displayed an isotopic multiplet consisting of nine signals. The isotopic multiplet observed for the OH groups of 2 in acetone-d6 was simulated at different deuteration enrichments.

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Produktpräferenzanalyse

Cited by 67 publications

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A Conformationally Flexible Tetrahydroxycalix[4]arene Adopting the Unusual 1,3-Alternate Conformation

A Conformationally Flexible Tetrahydroxycalix[4]arene Adopting the Unusual 1,3-Alternate Conformation

Effect of using repeated and siderate crops on soil fertility, yield of cotton varieties, and technological quality indicators of cotton fiber in short rotation cropping systems

Isotopic Perturbation of the Conformational Equilibrium in Methylene-Functionalized Calixarenes

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