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21.
I. Yu. Chukicheva E. V. Buravlev L. V. Spirikhin A. V. Churakov A. V. Kutchin 《Russian Chemical Bulletin》2006,55(10):1819-1823
The hydroxymethyl, pyridinium methyl, or dialkylaminomethyl groups were introduced into the aromatic ring of the o-isobornylphenol molecule.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1754–1757, October, 2006. 相似文献
22.
以2-[N-(N'-苄基-L-脯氨酰)氨基]二苯甲酮的甘氨酸席夫碱Ni(Ⅱ)配合物为原料,经Aldol羟甲基化,脱水,Michael加成和水解反应及离子交换层析,合成了4个(S)-β-取代-α-氨基酸衍生物,产率60%~75%,ee值90%~95%,其结构经~1H NMR和元素分析确证。 相似文献
23.
Oliver Steinhof Éléonore J. Kibrik Günter Scherr Hans Hasse 《Magnetic resonance in chemistry : MRC》2014,52(4):138-162
Urea–formaldehyde resins are bulk products of the chemical industry. Their synthesis involves a complex reaction network. The present work contributes to its elucidation by presenting results from detailed NMR spectroscopic studies with different methods. Besides1H NMR and13C NMR,15N NMR spectroscopy is also applied.15N‐enriched urea was used for the investigations. A detailed NMR signal assignment and a model of the reaction network of the hydroxymethylation step of the synthesis are presented. Because of its higher spectral dispersion and the fact that all key reactions directly involve the nitrogen centers,15N NMR provides a much larger amount of detail than do1H and13C NMR spectroscopy. Symmetric and asymmetric dimethylol urea can be clearly distinguished and separated from monomethylol urea, trimethylol urea, and methylene‐bridged urea. The existence of hemiformals of methylol urea is confirmed. 1,3,5‐Oxadiazinan‐4‐on (uron) and its derivatives were not found in the reaction mixtures investigated here but were prepared via alternative routes. The molar ratios of formaldehyde to urea were 1, 2, and 4, the pH values 7.5 and 8.5, and the reaction temperature 60 °C. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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25.
A. N. Kravchenko A. S. Sigachev G. A. Gazieva E. Yu. Maksareva N. S. Trunova K. A. Chegaev K. A. Lyssenko D. V. Lyubetsky M. I. Struchkova M. M. Il’in V. A. Davankov O. V. Lebedev N. N. Makhova V. A. Tartakovsky 《Chemistry of Heterocyclic Compounds》2006,42(3):365-376
The N-hydroxymethylation, N-acetylation, and N-acetoxymethylation of mono-, di-, and trialkylglycolurils by reaction with
the electrophilic reagents formaldehyde and acetaldehyde have been studied. General methods have been developed for the preparation
of mono-, di-, and tri-N-hydroxymethylglycolurils by treatment of differently substituted N-alkylglycolurils with formaldehyde
(as hemiformal in methanol) and the synthesis of di-N-and tri-N-acetyl-or N-acetoxymethylglycolurils via the electrophilic
substitution of hydrogen atoms for an acetyl group at the nitrogen or oxygen atoms in the hydroxymethyl groups of glycolurils
using acetic anhydride. The regioselectivity of the reaction of the 2-t-Bu-and 2-c-C6H11-glycolurils with formaldehyde has been shown to yield a 4,6-di(hydroxymethyl) derivative. It was found that the hydroxymethylation
of 2,4-and 2,6-dialkylglycolurils occurs regioselectively with a stoichiometric ratio of glycoluril to hemiformal and permits
preparation of their mono-and dihydroxymethyl derivatives. The enantiomeric analysis of the obtained compounds has been carried
out for the first time using HPLC on chiral phases. X-ray analysis has been carried out on the previously unreported racemic
2,6-diacetoxymethyl-4,8-dimethylglycoluril.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 411–423, March, 2006. 相似文献
26.
Dr. Hamish B. Hepburn Prof. Dr. Timothy J. Donohoe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):1963-1967
The activation of pyridinium salts with electron-withdrawing heterocycles enables an iridium-catalyzed reductive hydroxymethylation reaction to proceed smoothly, facilitating the preparation of useful 3D heteroaryl-substituted functionalized piperidines. The methodology is used to prepare 3-hydroxymethylated analogues of pharmaceutical agents. Mechanistically, formaldehyde acts as both a hydride donor and the electrophile, leading to the formation of two new carbon–hydrogen bonds and one new carbon–carbon bond under relatively mild conditions. 相似文献
27.
This paper describes an attempt to develop a durable finishing method in order to improve the fire performance of polyamide 66 fabrics. Hydroxymethylation with a 36% formaldehyde aqueous solution in association with a pad‐curing process to enable the fabric to react with flame‐retardant solutions was used in the finishing process. The fire performance of treated samples was characterized by limiting oxygen index (LOI) and vertical flammability tests, and the results show that the LOI value can increase from 21.6% to 46.2%. The thermal behavior of untreated and treated polyamide 66 fabrics was investigated by using thermogravimetic analysis and differential scanning calorimetry. Furthermore, residual char of treated fabric sample is much higher than that of untreated fabric sample. Fourier transform infrared spectroscopy proves that the substituted hydroxymethyl groups do exist on the molecular chain of polyamide fabric sample after surface modification. The morphology of residue char of polyamide 66 fabric samples was analyzed by scanning electron microscope, and the mechanical properties were also investigated and discussed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献