the solution being titrated is made 12M in chloride ion, the decomposition rate is diminished to 0.3% per minute, but almost no chlorination of benzamide was noticed after 30 minutes. Bromine was also substituted for chlorine, but no ,IT-bromination was noticed in a reasonable time period.The following technique was then developed to eliminate errors due to the slight instability of the chlorinating agent. A direct titration was carried out, but the first experimental point after the end point was taken with only a ilight excess (usually about 25y0) of hypochlorite. The remaining points, which determined the second segment of the titration curve, were then assumed to be constant if the current decreased less than 1 pa. per minute.This procedure can be used successfully for primary aliphatic amides and for aromatic amides which are not substituted or which are substituted only with alkyl groups. The presence of other functional groups substituted on the aromatic ring in general causes interference in the determination of the amide group.Electron-withdrawing groups such as nitro and carboxyl reduce the rate of N-chlorination, and also adversely affect the equilibrium constant. Electron-donating groups activate the ring so that chlorination of the ring takes place readily, and the exact stoichiometry of the titration reaction becomes uncertain. In addition, substituted groups such as amino, carbonyl, and hydroxy are easily oxidized by hypochlorous acid in the titration medium.Preliminary experiments indicate that a possible solution to this problem of interference by ring substituents is exhaustive bromination in acid solution. If the unknown sample is treated w-ith bromine, most of the ring sites which would ordinarily be chlorinated during the titration are brominated. Also, easily oxidizable groups are oxidized by the bromine, and the excess bromine can then be driven off by heating. t-nder these conditions bromination on the amide nitrogen does not take place.

In Reaktionen mit Carbonylverbindungen fungieren 2-Oxosulfonamide nicht nur monofunktionell als Keton, methylenaktive Verbindung oder Sulfonamid, sondern hlufig auch bifunktionell unter Bildung cyclischer Verbindungen. Sie kdnnen somit als neuartige Bausteine fur die Synthese von Heterocyclen dienen. 2-Oxosulfonamides, 111). -Reactions of 2-Oxosulfonamides with Carbonyl CompoundsIn reactions with carbonyl compounds 2-oxosulfonamides not only act monofunctionally as ketones, active-hydrogen compounds or sulfonamides, but often they react bifunctionally with formation of cyclic compounds. They thus can serve as novel building blocks for the synthesis of heterocycles.Wahrend 3-Oxobutanamid (Acetessigsaureamid, 1) eine seit langem bekannte') und fur die Synthese von Heterocyclen vielfiiltig eingesetzte Verbindung darstellt 3), ist das sulfonylanaloge 2-Oxopropansulfonamid (Acetonsulfonamid, 2) erst seit kurzem durch Oxidation von 2-Hydroxypropansulfonamid zuganglich4). Reaktionen mit AldehydenIn Abhangigkeit von den Reaktionsbedingungen und den Reaktionspartnern vermag 2 rnit Aldehyden unterschiedliche Typen von Reaktionsprodukten zu bilden. Bei Basenkatalyse (Kaliumhydroxid) reagiert 2 als Methylenkomponente kinetisch kontrolliert mit 2 Aquivalenten Benzaldehyd zum Heterocyclus 6, der auch mit p -und m-sub-0 VCH Verlagsgesellschaft mbH, D

No abstract

Three classes of new chiral dopants were synthesized and their properties in a non-chiral host mixture were measured. An extremely large spontaneous polarization (77 nC/cm2 at 25°C) was induced by 10% dopant in one case. Molecular mechanics calculations reveal that such a high polarization is predominantly obtained by steric hindrance around the chiral center. This steric effect also influences other physical properties such as helical twisting power. In addition the relationship between electro-optical properties and spontaneous polarization (Ps) are studied. It is apparent that higher Ps does not always improve switching time and bistability.

Further preparative and kinetic studies are necessary before it can be decided whether N-halogen compounds (R-NHX) react via nitrenes or by a nucleophilic substitution mechanism. The same is true for the conversion with ferrous oxalate at about 300 "C of 0-nitrobiphenyl [72] or o-nitrobiphenylamine [73] into carbazole (58) and 9,lO-dihydrophenazine (59), respectively, and for the transformation of 2-(o-nitrophenyl)pyridine into ammonium nitreniate (60). The latter is also formed on thermal decomposition but not on exposure to ultraviolet radiation of 2-(o-azidophenyl)pyridine [74].