Synthesis,identification and properties of some β-aminoalanine derivatives

A number of new β-(N-alkylamino) alanines have been synthesized from acetyldehydroalanine. Using keratin as a cystine-containing protein, it has been shown that, on treatment with a series of amines, β-(N alkylamino) alanine residues are formed in varying amounts in the protein, depending on the structure of amines applied.     

Effect of syndiotacticity on the aqueous poly(vinyl alcohol) gel 3. Mechanical property of gel

Summary The mechanical property of aqueous gel was studied using the PVA having the content of syndiotacticity in diad from 58.4 and 66.2%. The elastic modulus of gels was 105–106 dyne/cm2 and the variation of the elastic modulus of gel with the rise of temperature was corresponded with the variation of the concentration of PVA in gel accompanying syneresis. The elastic modulus of gel having the same content of syndiotacticity and concentration of PVA increased in the order as follows, the first is the gel chilled at room temperature, the second is the gel chilled at 60 °C and last is the gel chilled at 0 °C. The variation of the elastic modulus of gel with the rise of temperature became smaller with increasing content of syndiotacticity. The increase of elastic modulus is considered to be attributed to the further growth of stronger junctions through the recrystallization followed by syneresis rather than the entropic effect of polymer networks with the rise of temperature.

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Zusammenfassung Es wurden die mechanischen Eigenschaften wßriger Gele aus Polyvinylalkohol untersucht, mit Gehalten an Syndioaktizität in Diaden zwischen 58,4 und 66,2%. Die elastischen Moduln der Gele lagen bei 105 bis 106 dyn/cm2 und die Variation der elastischen Moduln der Gele mit Steigerung der Temperatur entsprach der Konzentrationsänderung von Polyvinylalkohol im Gele gemäß der stattgefundenen Synärese. Der elastische Modul des Gels mit konstantem Gehalt an Syndiotaktizität und Konzentration des PVA steigen in folgender Weise: Zuerst das Gel abgekühlt bei Raumtemperatur, dann das Gel abgekühlt bei 60 °C und zuletzt das Gel erstarrt bei 0 °C. Die Variation der elastischen Moduln mit steigender Temperatur wird kleiner mit steigendem Gehalt an Syndiotaktizität. Das Anwachsen der Moduln sollte vermutlich dem weiteren Wachstum strengerer Kopp lungen durch Rekristallisation infolge der Synärese zuzuschreiben sein mehr als einem Entropieeffekt der polymeren Netzwerke mit steigender Temperatur.

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With 6 figures and 2 tables

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Part 2. cf. reference 2.     

Pyridinium salts

New 4- (benzazol-2-yl)pyridinium salts have been synthesized. Their reduction in a neutral medium with sodium tetrahydroborate has given 2-(1,2,5,6-tetrahydropyridin-4-yl)benzazoles. The catalytic hydrogenation of the latter leads to piperidine derivatives which have also been synthesized by an independent route.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 104–107, January, 1974.     

Phosphorus in organic synthesis—VII : Diphenyl phosphorazidate (DPPA). A new convenient reagent for a modified curtius reaction

A simple one-step conversion of carboxylic acids to urethanes was achieved by diphenyl phosphorazidate (DPPA). The reaction procedure is quite simple, occurring by refluxing an equimolecular mixture of a carboxylic acid, DPPA, and triethylamine in the presence of a hydroxyl component. Aromatic, aliphatic, and heterocyclic carboxylic acids underwent rearrangements in satisfactory yields. As this modified Curtins reaction is much simpler and less laborious than the classical Curtius reaction and proceeds under mild conditions, it may have a broad synthetic utility.     

Extractive substances ofLarix dahurica

Summary The quantitative determination of quercetin and dihydroquercetin in the total flavonoids ofLatrix dahurica has been effected by the use of thin-layer chromatography on Kapron for separating the mixture with subsequent elution of the spots and colorimetry of the eluates obtained. The methanol-dimethylformamide (1:1) system was used as the eluate. It has been found that the flavonoids of the heartwood ofLatrix dahurica contain a predominating amount, 69% of dihydroquercetin, the amount of quercetin being 11%.Khimiya Prirodnykh Soedinenii, Vol. 3, No. 5, pp. 298–301, 1967     

Elemento-Organic Amines and Imines

Amines with mixed substituents containing two or three El? N bonds

1 El = a higher IVa, Va, or VIa element; by IVa, Va, and VIa elements are meant elements of the IV, V, and VI main groups of the periodic system

. are relatively stable if one or two of these bonds are (CH₃)₃ Si? N bonds. IR and ¹H? NMR studies indicate that the (p → d)π bond components of the element-nitrogen bonds steadily decrease from silicon, phosphorus, and sulfur toward their higher homologs. Because of the differences in the polarities of the element-nitrogen bonds, these substances can be used for selective insertion and cleavage reactions. The reaction of metalated N-silylaminoarsines with methyl chloride as well as the reaction of metalated N-trimethyl(IVa)-element-substituted amino-tert-butylphosphines with halogenotrimethyl(IVa) element compounds open new, simple routes for the conversion of elemento-organic amine systems into imine systems. The problem of reversible and irreversible (CH₃)₃ El ligand migration (1,3 shift) is discussed for trimethyl(IVa)element-substitued benzamidines, diaminophosphines, aminoiminophosphoranes, sulfinamides, and aminosulfimines.     

Intramolecular hydrogen bond in substituted 3-hydroxypyridines

To explain the character of the intramolecular hydrogen bond in substituted 3-hydroxypyridines, the chemical shifts in the NMR spectra of the hydroxyl group and the IR spectra were studied. It was established that the stability of the intramolecular hydrogen bond of the O-HNR₂ type in substituted 3-hydroxypyridines increases when compared with the corresponding phenols, while an opposite pattern is observed for bonds of the O-H0₂ N type. An approximate evaluation of the energy of the intramolecular hydrogen bond in substituted 3-hydroxypyridines was achieved. When reacting with bases of the same strength, 3-hydroxypyridine forms more stable complexes than phenol.