Solid–gas reactions. Part I. Bromination

Abstract

Solid ap-unsaturated acids. amides. and ketones yield, on exposure to bromine vapour a t room temperature, the ' trans-adduct ' in quantitative or near-quantitative yield even where addition of bromine in solution has been reported to be difficult. Polymorphic forms of several compounds differ in their rates of bromine uptake and addition.That crystal texture plays a role is suggested by the fixation of bromine in compounds which in the pure state add bromine slowly but which do so more rapidly in the presence of small amounts of impurities (e.g. photo-dimer or saturated derivatives).PREVIOUS publications concerned with solid-state reactions have stressed the high degree of topochemical control in photochemical pr0cesses.l We now explore the range and limitation of the topochemical concept in these two-phase, two-component reactions. Schmitt showed in 1863 that solid cinnamic acid reacts with bromine vapour to give cinnamic acid dibromide [re-this type of reaction have since a~peared."~ In view of the experimental simplicity of the reaction it was of interest to establish its general applicability; we also hoped to find examples suitable for more detailed analysis of the various processes involved in reaction (l), such as diffusion of bromine into the lattice, formation of charge-transfer complexes,* &.

Introduction of Halogen Atoms into Organic Compounds Under Solvent- Free Reaction Conditions

“…Addition of gaseous bromine to olefines was first performed in 1863 [76], and was later studied extensively [52,53,56,60,61,70,[77][78][79][80][81][82]. Like many other olefines, Nvinylphthalimide (B6a) and N-vinylsaccharin (B6b) could be brominated successfully (Scheme B2) [60,61], while treatment of dibenzobarrelene (B8) with bromine vapor resulted in rearrangement and formation of optically active B9.…”

Crystallographic studies of dehydrohalogenation in solid meso-dibromobutane derivatives. III. Conformational analyses and the stereo course of the reaction

“…This argument seems to hold in the present case since the density of (Ilia) is less than that of (IIIb) ( Table 1, part II) and the intermolecular forces in the former are weaker as indicated by the larger values of the thermal vibrations at room temperature. The different rates of gas/solid bromination in polymorphic forms of mesaconic acid (Hadjoudis et al, 1972) were also attributed to different rates of bromine diffusion resulting from different molecular packing modes.…”

“…period, prior to reaction, which is often observed in gas/solid reactions (Hadjoudis, Kariv & Schmidt, 1972) and the influence of crystal defects in increasing the reaction rate (Hadjoudis et al, 1972;Desvergne & Thomas, 1973) suggest that the gas diffuses to certain nucleation sites (e.g. dislocations, impurities) in the crystal where the reaction initiates and propagates therefrom into the bulk of the crystal.…”

A supramolecular 2:1 guanidinium-carboxylate-based building block for generation of extensive water channels and tetrameric water clusters in an organic material

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A bicyclic guanidine derivative is used here to form a hydrogen-bonded 2:1 complex with bipyridine dicarboxylic acid (1). The linear, rigid and charge assisted supramolecular building block has numerous additional hydrogen bond acceptors on the anti lone pairs of carboxylate O atoms and hence could be expected to display high propensity for inclusion of water molecules in the solid state [1]. We here show that, depending on the initial crystallization, it is in fact possible to utilize this property not only to build layered structures with clusters of water tetramers [2], [3], but also structures with extensive, unidirectional water channels [4] with a solvent accessible volume close to 20 % of the unit cell volume.

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“…A bicyclic guanidine derivative is used here to form a hydrogen-bonded 2:1 complex with bipyridine dicarboxylic acid (1). The linear, rigid and charge assisted supramolecular building block has numerous additional hydrogen bond acceptors on the anti lone pairs of carboxylate O atoms and hence could be expected to display high propensity for inclusion of water molecules in the solid state [1].…”