Hydroxytropylium chloride: the first crystal structure of an unfunctionalized hydroxytropylium ion

Abstract

The crystal structure of hydroxytropylium chloride, CHOH·Cl, the hydrochloride salt of tropone, is described, which represents the first crystallographic characterization of an unfunctionalized hydroxytropylium ion. Crystals were obtained serendipitously from a sample of chlorotropylium chloride after partial hydrolysis. This highlights the role of hydroxytropylium ions as an intermediate in the hydrolytic decomposition of halotropylium halides to tropone. The solid-state structure consists of layers, in which the hydroxytropylium and chloride ions interact via both strong hydrogen bonds formed by the hydroxy protons and weaker hydrogen bonds formed by the tropylium protons to produce a two-dimensional network.

Stimuli‐Responsive Organic Dyes with Tropylium Chromophore

“…Similarly,t he VT-UV/Vis absorption spectroscopy (Figure 4 bottom)s howedaclear intensification to the absorption peak at 567 nm (characteristic for organic dye Trop-DMA 4b)w hen the temperature increasef rom 10 8Ct o7 08C. Since we used a 1:1r atio of Ph 3 Pa nd Trop-DMA 4b and could only operate our apparatus within the 10-70 8Cr ange, it was not possible to obtain the complete formationo ft he complexes 7b or the complete dissociation to triphenylphosphine and organic dye 4b.This VT-UV/Vis study,however,confirmed the complexation equilibrium and hints that we can potentially use organic dye 4b and its analogues for applications in phosphine sensing and colorimetric analysis of chemical reactions, which Based on our previous works [22b-d] and recent findings from Pçthig and co-workers on crystallographic data of tropylium salts, [28] we believe that the tropylium moiety has differenta ffinities to counterions, especially in the halide series. The ionic charactero ft ropylium halide was observed to increase from chlorides alt to bromide salt.…”

Tropylium-promoted carbonyl–olefin metathesis reactions

“…The electrophilicity of the unsubstituted tropylium ion, as reported by Mayr and co-workers, is comparable to that of tritylium ions stabilized by electron-donating substituents such as a methoxy group. 14 The tropylium ion 15 might therefore be a suitable Lewis acid catalyst with adequate electrophilicity and oxophilicity for the COM reaction. 12 e Gratifyingly, our study demonstrated that the tropylium ion could indeed be used as an organic Lewis acid catalyst to efficiently promote the carbonyl–olefin metathesis reaction with good to excellent outcomes on a broad range of substrates.…”