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Pyrrole polymerization with acid

Pyrroles react with the conjugate acids of aldehydes and ketones to give carbinols (e.g. 67) which cannot normally be isolated but which undergo proton-catalyzed loss of water to give reactive electrophiles (e.g. 68). Subsequent reaction may lead to polymeric products, but in the case of reaction of pyrrole and acetone a cyclic tetramer (69) is formed in high yield. [Pg.54]

Pyrrole reacts with aldehydes and ketones under acidic conditions to form polymeric compounds. In many cases these are intractable resin-like materials however, with appropriate carbonyl compounds, interesting cyclic tetramers can be formed in very good yields. [Pg.423]

Other electrochemical processes of organic compounds on Pb electrodes or electrodes with UPD Pb have been studied - formaldehyde [323], oxalic acid [386], trichloro- and trifluoroethane [387], 1-phenylethylamine [388], 3-hydroxychi-nuclidine [388], dichlorodifluoromethane [389], polychlorobenzenes [390], 1-propa-nol [391], pyrrole polymerization [392], and inorganic compounds - phosphine [388] and sulfate(IV) ions [393]. Simultaneous catalytic or inhibiting influence of organic solvents - acetonitrile, dimethyl-sulfoxide, and Pb + presence on electrooxidation of small organic molecules on Pt electrodes has been studied using on-line mass spectroscopy [394],... [Pg.827]

The effect of intrazeolite protons on pyrrole polymerization in faujasite with ferric ions was examined, in order to distinguish the relative influence of acidity and the one-electron oxidant. If water was co-adsorbed with pyrrole, the authors could prepare materials with conductivities vaiying over a wide range. It is not clear to what extent the conductivity is due to surface-adsorbed polypyrrole, because similar simthetic methods also produced pol)mier coatings on amorphous aluminosilicates. [Pg.307]

Mono-C-alkylation of pyrroles cannot be achieved by direct reaction with simple alkyl halides, either alone or with a Lewis-acid catalyst, for example pyrrole does not react with methyl iodide below 100 °C above about 150 °C, a series of reactions occurs leading to a complex mixture made up mostly of polymeric material together with some poly-methylated pyrroles. The more reactive aUyl bromide reacts with pyrrole at room temperature, but mixtures of mono- to tetra-allyl-pyrroles together with oligomers and polymers are obtained. [Pg.300]

Pyrrole reacts with A-chlorosuccinimide to give 2-chloropyrrole. However, with SO2CI2 or aq. NaOCl, one obtains 2,3,4,5-tetrachloropyrrole. A-Bromosuccinimide forms 2-bromopyrrole, and bromine forms 2,3,4,5-tetrabromopyrrole. Pyrroles are nitrated with HNO3 in acetic anhydride at -10°C to yield 2-nitropyrroles. Concentrated sulfuric acid causes polymerization of pyrroles, but at 100°C, pyridine-SO3 complex provides the corresponding pyrrole-2-sulfonic acids [35 a]. [Pg.89]

Pyrrole has been chemically polymerized with oxidants including sulfuric acid [87], bromine and iodine [88], copper(II) perchlorate [89], and iron(III) chloride [90]. Soluble polypyrrole can be prepared by the introduction of flexible side chains [91-93]. In contrast with the progress made in the synthesis of regioregular PTs, all 3-substituted polypyrroles reported so far have a regio-random structure. [Pg.549]

Deng and co-workers [171] synthesized A -(5-hydroxy-pentyl)pyrrole by reacting 5-amino-l-pentanol with 2,5-dimethoxytetrahydrofuran in refluxing acetic acid. They then attempted to react this monomer with acid groups on the surface of a polyester and to copolymerize it with pyrrole on the treated surface. They report that a smooth metallic-looking black polymeric film adhered strongly to the surface of the polyester with surface electrical resistance in the range of 0.3-20 Q. [Pg.499]

Another polypyrrole/polyamide composite film was obtained by the electrode coating method [84]. In this work the polyamide film was obtained in situ by coating a stainless steel electrode with a polyamic acid film followed by imidization with pyridine and acetic anhydride. The coated electrode was submitted to a constant current in a pyrrole/LiC104 solution in acetonitrile. The surface conductivity measured after detaching the composite film from the electrode showed a strong dependence on the charge density used in the synthesis, i.e. on the amount of pyrrole polymerized in the composite. The maximum value obtained was 2 S cm . Combination of polypyrrole with this polyamide was shown to increase markedly its thermal and environmental stability. [Pg.783]


See other pages where Pyrrole polymerization with acid is mentioned: [Pg.273]    [Pg.694]    [Pg.219]    [Pg.217]    [Pg.218]    [Pg.287]    [Pg.408]    [Pg.843]    [Pg.171]    [Pg.217]    [Pg.218]    [Pg.287]    [Pg.408]    [Pg.526]    [Pg.282]    [Pg.356]    [Pg.817]    [Pg.1010]    [Pg.204]    [Pg.817]    [Pg.172]    [Pg.849]    [Pg.154]    [Pg.440]    [Pg.115]    [Pg.587]    [Pg.655]    [Pg.1512]    [Pg.474]    [Pg.285]    [Pg.270]    [Pg.194]    [Pg.416]    [Pg.783]    [Pg.848]    [Pg.16]    [Pg.526]   
See also in sourсe #XX -- [ Pg.733 ]




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