Potassium pyrrole

The Teixidor team further improved upon this chemistry by covalently linking units of 109 to the polypyrrole monomer prior to electropolymerization.139 A [3,3 -Co(C2B<)H11)2] anion was covalently bound to a pyrrole via a spacer through one of its boron atoms by the reaction of the species [3,3 -Co(8-C4H802-l,2-C2B9H10)(r,2 -(C2B9H11)2] with potassium pyrrole, as functionalization through... 

The conjugate addition of pyrrole to a, 3-unsaturated esters catalyzed by potassium pyrrolate led to the formation of P-pyrrolyl esters <06SL77>. 

When pyrrole is treated with potassium (but not with sodium) or boiled with solid potassium hydroxide, potassium pyrrole C4H4NK is formed, which is the starting point for AT-deriva lives of pyrrole, since reaction of the potassium with halogen of organic compound and with carbon... 

Azaferrocene (206) has been prepared by the reaction of sodium pyrrole, cyclopentadienylsodium, and ferrous chloride,157 or better by the reaction of potassium pyrrole with cyclopentadienyliron dicarbonyl iodide.158 It has been found159 that dioxane is a better solvent than benzene for this latter reaction. This reaction has also been applied to 2,4- and 2,5-dimethylpyrrole,158 3-acetyl-2-methyl-and 3-acetyl-2,4-dimethylpyrrole,160 and 2-methylpyrrole.159 The 2-methylazaferrocene from this latter pyrrole has been resolved with (—)6,6 -dinitrodiphenic acid.159 A compound (207) believed to be an intermediate in the formation of azaferrocenes has been isolated.161... 

Heterocyclic compounds containing a nitrogen atom commonly undergo N-alkylation or C-alkylation. N-Methyl pyrrole can be prepared by interaction of methyl iodide with potassium pyrrole (40%). N-Carbethoxy pyrrole is made from chloroformic ester and potassium pyrrole. The C-alkylation of pyrroles has been discussed. 3-Alkylindoles are made by the alkylation and decarboxylation of indole-2-carboxylic acid. The conditions for alkylation of pyrrolidine are analogous to those employed for the alkylation of a secondary amine. Thus, pyrrolidine on treatment with n-butyl bromide and potassium hydroxide in boiling benzene is con-... 

The only six membered hetero-cyclic compound which we shall consider is the one analogous to pyrrole. It contains a hetero-cyclic ring of five carbons and one nitrogen just as pyrrole contains four carbons and one nitrogen. This compound is known as pyridine. That pyridine is a six membered ring analogous to pyrrole is proven by the fact previously referred to (p. 854), that potassium pyrrole by the action of chloroform takes up an additional carbon and yields a chlorine substitution product of pyridine. 

Preparation of potassium pyrrole and subsequent formation of /V-(p-toluenesulfonyl)pyrrole [Scheme 2(i)]... 

Pyrrole (20 ml, 289 mmol in 100 mL of dry THF) is added drop-wise to the suspension of molten potassium and heating is continued until the potassium has been completely consumed. The mixture of potassium pyrrole is cooled and may be stored or used directly. To store the potassium pyrrole, the solid must be filtered quickly at the pump under a blanket of nitrogen, washed well with dry THF and dried in a vacuum desiccator over P2O5. The dry solid (which is yellow in colour) can then be stored under nitrogen. For direct conversion to A/-(p-toluenesulfonyl)pyrrole, then proceed as in step 5 below. 

The mixture of potassium pyrrole is diluted with a further quantity of THF (100 mL) to facilitate partial dissolution of the white solid and a solution of recrystallized p-toluenesulfonyl chloride (40.6 g, 213 mmol) in dry THF (200 mL) is added drop-wise. (Care This rection is exothermic and addition should be controlled so that only slight warming occurs.) The mixture is then allowed to stir for 24 h. 

These copolymers are prepared first by reacting the pendant chloromethyl groups on a styrene/p-chloro-methylstyrene (88/12) random copolymer with potassium pyrrole in refluxing THF overnight and then electrochemically polymerizing pyrrole onto the pendant pyrrole moiety [164,165]. 

An approach used to improve the mechanical properties of polypyrrole was the graft copolymerization of pyrrole with pyrrole-derivatized polystyrene [152]. The base polymer was obtained by the copolymerization of styrene and 4-chloromethylstyr-ene, followed by reaction with potassium pyrrole. The copolymer was dissolved in acetonitrile together with a... 

Pyrrole carbinols were identified as new base-labile protecting groups for aldehydes. The optimal bases for the preparation of a pyrrole carbinol via the reaction of metal pyrrolates with iso-butyraldehyde were sought. Alkali metal pyrrolates performed better than their alkaline earth counterparts. Lithium and sodium pyrrolates prepared via the deprotonation of pyrrole with n-BuLi, LHMDS, and NaHMDS afforded the corresponding pyrrole carbinol in 90%, 85% and 85% yields, respectively, whereas potassium pyrrolate obtained using KHMDS afforded the pyrrole carbinol in a lower yield (45%) (eq 75). ... 

The electronic structure of pyrrole allows us to understand not only the very weak basic properties of pyrrole but also its acidic character (p. 17). Pyrrole reacts with fused potassium hydroxide, or with potassium, to give potassium pyrrole, G4H4NK. The reaction with potassium proceeds smoothly, with evolution of hydrogen, in ligroin solution. Sodium pyrrole has not been obtained under such conditions, but pyrrole reacts with sodamide in liquid ammonia to give a compound C4H4lWa,NH3. This loses ammonia at 20°. Calcium and silver pyrrole can be prepared in the same way . 

With potassium pyrrole, the proportion of N-substitution increases with increasing solubility of the salt in the medium used. 

Deuterium exchange between pyrrole and deuterium oxide is slow at pH >2, and only monosubstitution occurs. At pH 1-2, more than one hydrogen atom is replaced at a measurable velocity, and at pHrapid exchange of all five hydrogen atoms occurs. Comparison of the monodeuteropyrrole formed at pH >2 with the compound prepared from deuterium oxide and potassium pyrrole proves it to be l-flf-pyrrole. Clearly, from pyrrole-t/s symmetrical pyrrole- /4 can be obtained by reaction with water ... 

It will be noticed that reaction at the pyrrole nitrogen atom usually involves either the use of potassium pyrrole or of alkaline conditions. It is not surprising, therefore, that in the presence of trimethylbenzylammonium hydroxide, pyrrole undergoes N-cyanoethylation with acrylonitrile e and that the sodium salt of 2-nitropyrrole behaves in the same way293. Related reactions are the formation of 1-pyridylethylpyrrole from the sodium pyrrole and 2-vinylpyridinei37 and of 1-vinylpyrrole from acetylene and potassium pyrrole. ... 

With electron-deficient acetylenes, the dithioate anions can be involved in the reactions of both 1,3-anionic cyclo- and nucleophilic additions [550], The reactions of 1,3-anionic cycloaddition are typical provided that the central atom of [S-C-S] has aromatic substituents ensuring the anion stabilization [551,552], For instance, potassium pyrrole-l-carbodithioate selectively reacts (acetonitrile, -30°C, CH3COOH) with dimethyl ester of acetylenedicarboxylic acid to form rapidly polymerizing 2-(pyrrol-l-yl)-4,5-dimethoxycarbonyl-l,3-dithiol (Scheme 2.80) [552,553]. 

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