Search results for "Condensation"
showing 10 items of 468 documents
The reaction of 2,4,5,6-tetraaminopyrimidine with chalcones
2000
The reaction of the tetraaminopyrimidine 1 with the chalcones 2a-f yields, in the presence of catalytic amounts of acetic acid, the 1H-pyrimido[4,5-b][1,4]diazepine derivatives 3a-f. The cyclization process consists of a condensation reaction and a Michael type addition.
Eine oligomeranaloge friessche umlagerung oligomerer 2-acetoxy-1,3-phenylenmethylene
1979
α-Hydro-ω-hydroxypoly(5-chloro-2-hydroxy-1,3-phenylenemethylene)s (1a, b), the oligomeric condensation products from 4-chloro-2,6-bis(hydroxymethyl)phenol and 4-chlorophenol with hydrochloric acid in 1,4-dioxane, could be completely dehalogenated at room temperature and atmospheric pressure with hydrogene/Raney-Ni. The resulting oligomers 2a, b were esterified with acetic anhydride, and the esters 3a, b were subjected to a oligomer analogous Fries rearrangement to form the linear α-hydro-ω-hydroxypoly(5-acetyl-2-hydroxy-1,3-phenylenemethylene)s 4a and 4b. The characterization of the products was mainly done by spectroscopic methods.
An Unexpected Three-Component Condensation Leading to Amino- (3-oxo-2,3-dihydro-1H-isoindol-1-ylidene)- acetonitriles
2004
The reaction of 2-carboxybenzaldehyde with primary amines in the presence of cyanide leads to the formation of 2-substituted amino(3-oxo-2,3-dihydro-1H-isoindol-1-ylidene)acetonitriles. These compounds originate from the condensation of 2-carboxybenzaldehyde with the amine and two molecules of hydrogen cyanide and represent a novel class of isoindolinones.
ChemInform Abstract: Sequential Suzuki/Asymmetric Aldol and Suzuki/Knoevenagel Reactions under Aqueous Conditions.
2012
Here we describe for the first time a sequential Suzuki/asymmetric aldol reaction. Such sequential approach was achieved through the combined use of an ionic liquid supported palladium catalyst and the organocatalyst trans-4-(2,2-diphenylacetoxy)proline. Suzuki and asymmetric aldol reactions were performed under aqueous conditions. The use of a palladium catalyst under basic conditions allowed also the first example of sequential Suzuki/Knoevenagel reaction. Reactions were carried out under aqueous conditions and products were isolated in good to high yields and, in the case of the Suzuki/aldol reaction, with diastereoselectivities up to 91:9 and enantioselectivities up to at least 99 %.
Rotational State Change of Acetonitrile Vapor on MCM-41 upon Capillary Condensation with the aid of Time-Correlation Function Analysis of IR Spectros…
2000
The infrared spectra of adsorbed acetonitrile on MCM-41 (porewidth = 3.2 nm) were measured at 303 K. In the CN stretching ν2 region, two bands were observed at 2265 cm− 1 and 2254 cm− 1, assigned to hydrogen-bonded molecules on surface hydroxyls of MCM-41, and physisorbed molecules in mesopores, respectively. We designate here the 2265 cm− 1 band as the ν2α band and the 2254 cm− 1 band as the ν2β band. The bandwidth of the fundamental transition ν2fβ, was obtained by removing the overlap with hot band transitions of the same mode, ν2α band, and other modes by least-squares fitting. Before capillary condensation, the relaxation time τ obtained from the bandwidth of the ν2fβ band was smaller …
Zur herstellung molekulareinheitlicher, über schwefelhaltige brücken verbundener, phenolischer zweikernverbindungen
1963
Phenole lassen sich mit Thionylchlorid mittels Aluminiumchlorid in hohen Ausbeuten zu molekulareinheitlichen Sulfoxyden kondensieren, die sich im praparativen Masstab einerseits zu Sulfiden reduzieren und andererseits zu Sulfonen oxydieren lassen. Die Sulfone konnen auch in guten Ausbeuten mittels Aluminiumchlorid durch Kondensation von Phenolathersulfochloriden mit Phenolathern und durch FRIESsche Verschiebung entsprechender Sulfonsaureester erhalten werden. Phenols can be condensed with thionylchloride using aluminium chloride as catalyst in good yields to molecularly defined sulfoxides, which can be preparatively reduced to sulphides or oxidised to sulphones. The sulphones were also obta…
Versuche zur umsetzung von methylendiphenolen mit glucosederivaten und zur kondensation von O-phenylglucosidderivaten
1981
Attempts to apply known methods of glucosidation to oligo[(hydroxyphenylene)methylene]s were not satisfying. The reaction of 4,4'-dimethyl-2,2'-methylenediphenol (1a) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide gave a monoglucoside in 11% yield. A second attempt, the condensation of suitable O-phenylglucoside derivatives was unsuccessful. From a series of O-phenylglucosides (4) only 4-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyloxy)benzylbromide could be condensed with O-(4-hydroxymethylphenyl)-2,3,4,6-tetra-O-acetylglucopyranose to the corresponding diglucoside of 4,4'-oxydimethylenediphenol (7). Condensation reactions of the O-phenylglucoside 4k, to obtain an O-glucosidized poly[…
Zur kinetik der polykondensation von phenolalkoholen
1952
Nach einer Ubersicht uber die reaktionskinetischen Verfahren bei der Phenol-Form-aldehyd-Harzbildung und ihre Ergebnisse wird an Hand der v. Eulerschen Reaktionskurven zur Hartung von Phenolalkoholen die Ubertragbarkeit der Floryschen Kondensationskinetik auf diese Hartung gezeigt. After a review of the kinetical methods of phenolic-resin formation and their results, it is demonstrated from the reaction curves of phenol alcohols, published by v. Euler and coworkers, that the kinetic of condensation developped by P. J. Flory in the polyesterification reactions, is applicable to the polyetherification of phenol alcohols.
Synthesis of Symmetrical 1,4-Diarylphthalazines
1975
Abstract It is well known that 1, 4-diarylphthalazines are prepared by condensation of the appropriate ortho-diaroylbenzenes with hydrazine hydrate.1 As ortho-diaroylbenzenes can be obtained by oxidation of ortho-dibenzylbenzenes, a rapid method is proposed to obtain the ortho-dibenzylbenzenes (Ia) and (Ib) by reaction of the highly reactive2 veratrol with para-chloro- or ortho-chlorobenzyl alcohol in sulfuric acid. The products obtained gave by oxidation the ortho-diaroylbenzenes (IIa) and (IIb), which were transformed into the 1,4-diarylphthalazines (IVa) and (IVb) by treatment with hydrazine hydrate.
Synthesis of pillar[7]arene
2012
Abstract The first synthesis of pillar[7]arene is reported with two methods. Method A: the FeCl 3 -catalyzed condensation reaction of 1,4-dimethoxybenzene ( 1 ) with paraformaldehyde in CHCl 3 gave dimethoxypillar[7]arene ( 3 ). Method B: the p -toluenesulfonic acid catalyzed condensation reaction of 2,5-bis(benzyloxymethyl)-1,4-dimethoxybenzene ( 2 ) in CH 2 Cl 2 gave compound 3 . Demethylation of 3 with BBr 3 gave pillar[7]arene ( 4 ). The pillar[7]arene might be a perspective macrocyclic host in host–guest chemistry.