Butatrien durch Thermolyse von Propiolsäure-(2-propinyl)ester

Flow thermolysis of 2-propynyl propiolate (5) at 580° afforded butatriene (6) (ca. 50%) and, as by-products, 4-methylene-2-cyclobuten-1-one (7) , 2-ethynylpropenal (8) , 1-penten-4-yn-3-one (9) , 4-penten-2-ynal (10) (total ca. 10%), along with some propynal, acetylene, CO₂ and CO. In the same way, propiolic acid (1,1-D₂)-2-propynyl propiolate (11) led to (1,1-D₂)-butatriene (12) and a little 4-((D₂)methylene)-2-cyclobuten-1-one (13). A mechanism is proposed for the transformation of 5 into 6 and of 11 into 12 , which also accounts for the formation of 7,8,9 and 10 , as well as 13. The position of one of the published ¹³C-NMR signals of butatriene (6) must be revised. Thermolysis of methyl- (1) and ethyl propiolate (2) resulted in small yields of 2-buten-4-olide (3) and 2-penten-4-olide (4).     

Bildung von 5,6-Dihydro-1,3(4H)-thiazin-4-carbonsäure-estern aus 4-Allyl-1,3-thiazol-5(4H)-onen

Formation of Methyl 5,6-Dihydro-l, 3(4H)-thiazine-4-carboxyiates from 4-Allyl-l, 3-thiazol-5(4H)-ones . The reaction of N-[1-(N, N-dimethylthiocarbamoyl)-1-methyl-3-butenyl]benzamid ( 1 ) with HCl or TsOH in MeCN or toluene yields a mixture of 4-allyl-4-methyl-2-phenyl-1,3-thiazol-5(4H)-one ( 5a ) and allyl 4-methyl-2-phenyl-1,3-thiazol-2-yl sulfide ( 11 ; Scheme 3). Most probably, the corresponding 1,3-oxazol-5(4H)-thiones B are intermediates in this reaction. With HCl in MeOH, 1 is transformed into methyl 5,6-dihydro-4,6-dimethyl-2-phenyl-1,3(4H)-thiazine-4-carboxylate ( 12a ). The same product 12a is formed on treatment of the 1,3-thiazol-5(4H)-one 5a with HCl in MeOH (Scheme 4). It is shown that the latter reaction type is common for 4-allyl-substituted 1,3-thiazol-5(4H)-ones.     

Bariumstannat‐Pulver durch hydrothermale Synthese und durch Thermolyse von Bariumzinn(IV)‐glykolaten. Synthese und Struktur von [Ba(C2H6O2)4][Sn(C2H4O2)3] und [Ba(C2H6O2)2][Sn(C2H4O2)3]·CH3OH

Barium Stannate Powders from Hydrothermal Synthesis and by Thermolysis of Barium‐Tin(IV)‐Glycolates. Synthesis and Structure of [Ba(C₂H₆O₂)₄][Sn(C₂H₄O₂)₃] and [Ba(C₂H₆O₂)₂][Sn(C₂H₄O₂)₃]·CH₃OH The hydrothermal reaction as well as the microwave assisted hydrothermal reaction of SnO₂·aq with barium hydroxide gives Ba[Sn(OH)₆] ( 1 ) as powder with bar like particles. Compound 1 of the same morphology can also be isolated from a hydrothermal reaction of [Ba(C₂H₆O₂)₄][Sn(C₂H₄O₂)₃] ( 3 ). The reaction of SnO₂·aq with Ba(OH)₂·8H₂O in ethylene glycol yields the glycolate [Ba(C₂H₆O₂)₄][Sn(C₂H₄O₂)₃] ( 3 ), which forms in methanol the solvate [Ba(C₂H₆O₂)₂][Sn(C₂H₄O₂)₃]·CH₃OH ( 4 ). Compounds 1 , 3 and 4 react at different temperatures to BaSnO₃ ( 2 ) consisting of powders with different morphologies; because of the grain size of the resulting powders compounds 3 and 4 are suitable as precursor for the fabrication of corresponding ceramics.     

Alkyl- und Arylsulfensäureanilide durch Cycloeliminierung von Alkenen aus Sulfimiden, 2. Thermolyse von 3-Alkylthiopropannitril-bzw. 3-Alkylthiopropansäuremethylester-S-(N-aryl)-imiden

Summary A series of alkyl- and arylsulfenanilides has been prepared by thermal cycloelimination of acrylonitrile or methyl acrylate from N-aryl sulfimides derived from 3-alkylthio-propionitriles or methyl 3-alkylthio-propanoates. Compared to reactions in earlier studies [1] cycloelimination proceeds much faster at very mild conditions, thus allowing a one-pot synthesis of sulfenanilides from corresponding 3-alkyl-thio-propionitriles or 3-alkylthio-propanoates.

     

Die Bildung von Gallium-Chalkogen-Heterokubanstrukturen durch Umsetzung der Alkylgallium(I)-Verbindung Ga4[C(SiMe3)3]4 mit Schwefel,Selen und Tellur

The Formation of Gallium Chalcogen Heterocubanes by the Reaction of the Alkylgallium(I) Compound Ga₄[C(SiMe₃)₃]₄ with Sulfur, Selenium, and Tellurium The alkylgallium(I) compound Ga₄[C(SiMe₃)₃]₄ 1 , which monomerizes in dilute solutions, reacts with elemental sulfur, selenium, and tellurium in boiling n-hexane to yield the corresponding Ga₄X₄R₄ cage compounds in a high yield. As shown by crystal structure determinations, the products have distorted Ga₄X₄ heterocubanes in their molecular centers with a slightly increasing distortion for the heavier chalcogen atoms. While the selenium and tellurium derivatives show a very low solubility in benzene, the sulfur compound dissolves readily accompanied by the dissociation into the (RGaS)₂ dimer.