The self-association of acetic acid in organic solvents at 25 °C has been investigated by infrared spectroscopy. The organic solvents used are n-hexane, carbon tetrachloride, toluene, benzene, chlorobenzene, chloroform, 1,2-dichloroethane, and dichloromethane. The spectra of the carbonyl region were fitted with four Lorentzian curves, two for acetic acid monomer and cyclic dimer and the other two for the linear dimer. The formation constants of the cyclic and linear species were determined over concentration range from 8.4 X 10"3 to 1.3 x 10"1 mol dm'3. The solvent effect on the dimerization is considered in relation to the solvent effect on the partition of the acid monomer.

Reaction of dithioic acids with dicyclohexylcarbodiimide has been found to give the corresponding bis(thioacy1) sulfides 1 in good yield, which are very useful thioacylating reagents under mild reaction conditions. Most of the aromatic thioanhydrides (1, R = aromatic) are fairly stable green crystals at room temperature, but the aliphatic ones (1, R = aliphatic) are unstable purple oils which dimerize at room temperature to give the dithietanes 5. The reactions with nucleophiles are discussed. Darstellung und einige Reaktionen von Bis(thioacy1)sulfidenDurch Umsetzung von DithiocarbonsBuren mit Dicyclohexylcarbodiimid wurden die Bis-(thioacy1)sulfide 1, die niitzliche und unter milden Reaktionsbedingungen einsetzbare Thioacylierungsmittel sind, dargestellt. Die aliphatischen Thioanhydride (1, R = Aliphaten) sind thermisch labile und feuchtigkeitsempfindliche purpurne Ole, die bei Raumtemperatur zu den Dithietanen 5 dimerisieren, wlhrend die meisten aromatischen Derivate (1, R = Aromaten) tiefgriine, einigermanen stabile Kristalle bilden. Einige Reaktionen mit Nucleophilen werden diskutiert. Bis(thioacy1) sulfides 1, the trithio analogues of acid anhydrides, are attractive compounds of spectroscopical and synthetical interest, especially in thioacylation.Their remarkable instability and sensitivity towards moisture, however, have prevented the isolation and characterization since the first description of 1 [R = (C2H,C0J2CHj by Wenzella) in 1900. Recently, we reported the first isolation of some simple bis(thioacy1) sulfides *) 1. In this paper, we describe more detailed preparation methods and some reactions with nucleophiles. Results and DiscussionFor the preparation of 1 the following five routes have been investigated in detail: a) Desulfurization of bis(thioacy1) disulfide with triphenylphosphine or trialkylphosphite.

No abstract

In the μ‐carbido complex (4), obtained as shown below, the tin atom is linked to the rhenium atoms via a carbide carbon atom which bonds like a carbyne to the rhenium (TPP stands for tetraphenylporphyrin). An impression of the spatial arrangement of the complexes of type (3), which are formed at only slightly higher temperatures than (4), is provided by the adjacent formula.

No abstract