Bildung von Mischkristallen bei Verbindungen vom Huréaulith-Typ

We investigated to what an extent mixed crystals of phosphates (arsenates) of Mn and Cd, [M₅(HPO₄)₂(PO₄)₂ · 4 H₂O], with Fe(II), Co, Ni, Zn and Cu can be formed.     

Die massenspektrometrische retro-Diels-Alder-Reaktion: 1, 2, 3, 4-Tetrahydroisochinolin und 1, 2, 3, 4-Tetrahydronaphthalin (Tetralin). 31. Mitteilung über massenspektrometrische Untersuchungen

The Mass Spectral retro-Diels-Alder-Reaction: 1,2,3,4-Tetrahydroisoquinoline and 1,2,3,4-Tetrahydronaphthaline (Tetraline) The retro-Diels-Alder reaction of 1,2,3,4-tetrahydroisoquinoline and of its N-acetyl derivative was confirmed on the basis of labelled derivatives (Scheme 2). Furthermore, the loss of ethylene was investigated with the 1,2,3,4-tetrahydronaphthalene- and 1,2,3,4-tetrahydronaphthalen-1-one-derivatives given in Schemes 4, 5 and 6. In the case of the 1,2,3,4-tetrahydronaphthalen-1-one-derivatives ethylene is lost via a retro-Diels-Alder reaction. The loss of ethylene from 1,2,3,4-tetrahydronaphthalene ( 1 ) and from its derivatives is a rather complex reaction (Scheme 8): 1/3 of ethylene is split off 1 ⁺ via a formal retro-Diels-Alder reaction, 2/3 are lost after a specific rearrangement. The ratio of these two fragmentation pathways depends very much on the substituents placed at the aliphatic and the aromatic rings, compare e.g. Table 4.     

Zeolite Membranes: From the Laboratory Scale to Technical Applications

Current trends and novel concepts in R&D of zeolite membranes like the seeding supported crystallization and the preparation of Al-containing zeolite membranes are discussed. The influences of adsorption and diffusion on the permeation properties of zeolite membranes are considered. Dehydration of ethanol by steam permeation and pervaporation as the first zeolite membrane based industrial separation is presented. Membrane supported dehydrogenation and esterification are discussed as possible applications of a catalytic membrane reactors. In memoriam Wolfgang Schirmer.     

(R)- and (S)-2-acetoxy-1,1,2-triphenylethanol - effective synthetic equivalents of a chiral acetate enolate

The enolate 3, easily available by double deprotonation of (R)-2- acetoxy-1,1,2-triphenylethanol (5), adds in a highly stereoselective manner to aldehydes. Hydrolysis of the adducts 6/7 affords the acids 2.     

Regioselektive synthese von daunomycinon und γ-rhodomycinon

Synthesis of daunomycinone ($\text{2}$) and γ-rhodomycinone ($\text{3}$) by regioselective addition of the Grignard reagents $\text{9b}$ and $\text{9d}$ to the anhydride $\text{4}$.