Alfons Saus

Photochemical hydroformylation of olefins with rhodium catalysts at elevated pressure

Abstract The catalytic activity of RhCl 3 and RhHCO(PPh 3 ) 3 towards hydroformylation, hydrogenation and isomerization of olefins such as 1-octene, styrene, 1,5- and 2,4-hexadiene is enhanced by UV-irradiation. The most active photocatalytic system consists of RhCl 3 and norbornadiene, which catalyses the hydroformylation of 1-octene even at room temperature. The photochemical reaction of norbornadiene itself at 80 bar CO/H 2 and 20 °C lead to a copolymer between norbornadiene and carbon monoxide, in contrast to the thermal reaction at 80 bar CO/H 2 and 80 °C which results in the formation of mono- and dialdehydes. A UV-autoclave allowing photochemical reactions at pressures up to 300 bar is described.

Thermal, photochemical and alcohol catalyzed formation of Co4(CO)12 from Co2(CO)8. Kinetics and mechanism

The kinetics of formation of Co4(CO)12 from Co2(CO)8 in n-heptane are complex and dependent on the reaction conditions (e.g. argon flow rate). The most probable reaction order is 0.5 and the activation energy <50 kJ/mol. The reaction is enhanced by UV light (o ⩽ 0.01) and addition of small amounts of ethanol. The reaction mechanism is discussed in terms of a chain reaction with HCo(CO)4 or Co(CO)4 as a chain carrier and/or pathway via Co2(CO)7.

Photocatalytic hydrogenation of dienes with chromium carbonyls

Abstract The photochemical hydrogenation of norbornadiene (NBD) in the presence of Cr(CO) 6 or Cr(CO) 4 NBD at normal pressure yields nortricyclene (NTC) and norbornene (NBN) in a ratio of 3/1. With increasing hydrogen pressure the NTC/NBN ratio changes to 0.8/1 at 100 bar H 2 , due to a faster formation of norbornene. The formation of NBN is more strongly inhibited than that of NTC by 50 bar of CO. Other conjugated dienes such as cyclohexadiene, isoprene, or 1,3-pentadiene give exclusively 1.4-hydrogenation products. The results are rationalized by a mechanism in which the 1.4-addition and the NTC formation are initiated by a CO dissociation, whereas the norbornene is formed via initial cleavage of a Crdiene bond in the Cr(CO) 4 diene catalyst.

Synthese und Strukturaufklrung von 7-Alkylamino-7-phenyl-8-thioxo-1,2,3,4,5,6-hexathiocanen: ber die gemeinsame Einwirkung von elementarem Schwefel und gasfrmigem Ammoniak auf Ketone, 53. Mitt.; Einwirkung von Schwefel und Aminen auf Acetophenon, 7. Mitt.

Durch die gemeinsame Einwirkung von elementarem Schwefel und primaren Aminen (Methyl-, Athyl-, n-Propyl-, Isopropyl-und n-Butylamin) auf Acetophenon bei Raumtemp. entstehen die bisher unbekannten 7-Alkylamino-7-phenyl-8-thioxo-1,2,3, 4,5,6-hexathiocane. Die Struktur dieser neuen Verbindungsklasse wird durch Abbaureaktionen undNMR-Untersuchungen bewiesen. Dieselben Verbindungen erhalt man in besseren Ausbeuten bei der Reaktion der entsprechenden Acetophenonimine mit Schwefel in Gegenwart freien Amins. Einige bisher unbekannte Acetophenonimine wurden synthetisiert. 7-Alkylamino-7-phenyl-8-thioxo-1.2.3.4.5.6-hexathiocanes —so far unknown compounds — are formed by the reaction of excess elementary sulfur and primary amines (methyl-, ethyl-, n-propyl-, i-propyl- and n-butylamine) with acetophenone at room temperature. The structure of this new class of compounds is proved by degradation reactions andNMR-spectrum. The same compounds can be produced in better yields by the reaction of the corresponding acetophenone imines with sulfur in the presence of free amines. Some formerly unknown acetophenone-imines were synthesized.

The catalytic activity of metal carbonyl cluster compounds. Hydroformylation and hydroesterification catalyzed by Co4CO12 and Co2(CO)8

Abstract The carbonyl complexes Co2(CO)8 and Co4(CO)12 catalyze the hydroformylation and hydroesterification reactions via the same catalytic cycle. The entry into this cycle via HCo(CO)3 is easier with Co4(CO)12 than with Co2(CO)8, and so the former is the more active catalyst.

The triplet energies of butenedioic acid derivatives

Abstract The oxygen perturbation spectra of butenedioic acid derivatives were measured and the vertical triplet energies were determined to be 62 kcal mol−1 for fumaronitrile, about 66 kcal mol−1 for dimethyl fumarate, 71 kcal mol−1 or more for dimethyl and 72 kcal mol−1 for maleic anhydride.

Zur Kenntnis der Reaktionsfähigkeit des unsubstituierten Thiomorpholins und alkylsubstituierter Thiomorpholine. 3. Mitt

A new synthesis of thiomorpholine by ring closure of β-chloro-β′-aminodiethylene-sulfide with potassium hydroxide is reported. Numerous reactions of thiomorpholine (1) and, especially, 2-methyl-3-ethyl-thiomorpholine (2) are described such as acylation, diacylation (3–43), reactions with sulfonic acid chlorides (44–52), isocyanates (53–61, 70–75), diisocyanates (62–66, 76–78) and isothiocyanates (67–69, 79–82), alkylation reactions (83–111) and the synthesis of thiomorpholino-dithiocarbamates (112–121).

Gemeinsame Einwirkung von elementarem Schwefel und Äthylenimin auf Ketone, 3. Mitt.: Über die gemeinsame Einwirkung von elementarem Schwefel und gasförmigem Ammoniak auf Ketone, 74. Mitt.

ZusammenfassungBei der Einwirkung von Äthylenimin und Schwefel auf Methyläthylketon, Methylisopropylketon und Äthylisopropylketon entstehen strukturisomere 5,6-Dihydro-1,4-thiazine (1–6) und als Nebenprodukte die dem jeweiligen Keton entsprechenden Thiazolidine (7–9).Die 5,6-Dihydro-1,4-thiazine werden mit Ameisensäure in N-Formylthiomorpholine (10–15) übergeführt, die mit verd. HCl glatt zu den entsprechenden Thiomorpholinen (16–21) hydrolysiert werden.Das Verhältnis der Thiomorpholin-Isomerenpaare wird gaschromatographisch quantitativ bestimmt.AbstractThe reaction of ethylenimine and sulfur with methyl ethyl ketone, methyl isopropyl ketone and ethyl isopropyl ketone, resp., yields the structurally isomeric 5.6-dihydro-1.4-thiazines (1–6) and as by-products the thiazolidines (7–9) derived from the corresponding ketones.The 5.6-dihydro-1.4-thiazines are converted with formic acid to the N-formyl thiomorpholines10–15, which are easily hydrolyzed with dilute hydrochloric acid to the corresponding thiomorpholines (16–21). The ratio of the pairs of structurally isomeric thiomorpholines is determined by quantitative gas chromatography.

Der Mechanismus der Bildung von 2-methyl-2,4-diphenylimid-azolin-Δ3-thion-(5) bei der Einwirkung von Schwefel und Ammoniak auf Acetophenon

Der Mechanismus der bei Raumtemp. fast quantitativ zu 2-Methyl-2,4-diphenylimidazolin-Δ3-thion-(5) (II) fuhrenden Reaktion zwischen Acetophenon, NH3 und uberschussigem Schwefel wird erortert. Zwischenstufen zu II sind ω,ω-Dimercaptoacetophenon (VII), das durch mehrfache Sulfhydrylierung des Acetophenons entsteht, und Phenylglyoxylsaurethionamid (I). Letzteres kondensiert mit Acetophenon in Gegenwart von NH3 zu II. Dem Sulfhydrylierungsschritt ist die Bildung derSchiffschen Base aus Acetophenon und Ammoniak vorgelagert.

Acylgruppenwanderung in N-Acyl-2H-imidazol-4(3H)-thionen

On acylating 2H-imidazole-4(3H)-thiones the orange to violet crystalline N-1-acyl-2H-imidazole-4(3H)-thiones1 a–18 a are formed, the thermal stability of which depends on the acyl group and the substituents in the heterocyclic ring system. Thus the N-aroyl-2,2,5-trimethyl-2H-imidazole-4(3H)-thiones13 a–16 a are stable on being heated to the melting point, while1 a–12 a are converted quantitatively to the corresponding S-aroyl-2H-imidazole-4-thiols1–12. Rearrangement is faster when the heterocyclic ring bears bulky substituents. The aliphatic N-acyl compounds17 a and18 a are thermally unstable. This N → S acyl group migration, described here for the first time, is shown to proceed by an intermolecular mechanism.