Pyrrole Hydrogen Research Articles

ChemInform Abstract: Preparation and Crystal Structure of an Imidazolate‐Bridged Polynuclear Complex ((Cu(im)(dien))n)(ClO4)n (dien = diethylenetriamine), and Its Properties in Dimethyl Sulphoxide Solution.

AbstractA precursor complex (I), obtained by reaction of Cu(ClO4)2 in MeOH/MeCN with diethylenetriamine in water and imidazole in MeOH, undergoes deprotonation of the pyrrole hydrogen in the coordinated imidazole in EtOH by the addition of a strong base or in alkaline aqueous solution containing an excess of NaOH, to give the title compound (II).

Catalytic hydrogenation of pyrroles at atmospheric pressure

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic hydrogenation of pyrroles at atmospheric pressureHans Peter Kaiser and Joseph M. MuchowskiCite this: J. Org. Chem. 1984, 49, 22, 4203–4209Publication Date (Print):November 1, 1984Publication History Published online1 May 2002Published inissue 1 November 1984https://doi.org/10.1021/jo00196a020RIGHTS & PERMISSIONSArticle Views1628Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (942 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: INFLUENCE OF THE METAL CENTERS ON THE PKA OF THE PYRROLE HYDROGEN OF IMIDAZOLE COMPLEXES OF (NH3)53+, M(III) = CO(III), RH(III), IR(III), RU(III)

Chemischer InformationsdienstVolume 15, Issue 39 Organoelement Compounds ChemInform Abstract: INFLUENCE OF THE METAL CENTERS ON THE PKA OF THE PYRROLE HYDROGEN OF IMIDAZOLE COMPLEXES OF (NH3)53+, M(III) = CO(III), RH(III), IR(III), RU(III) M. F. HOQ, M. F. HOQSearch for more papers by this authorR. E. SHEPHERD, R. E. SHEPHERDSearch for more papers by this author M. F. HOQ, M. F. HOQSearch for more papers by this authorR. E. SHEPHERD, R. E. SHEPHERDSearch for more papers by this author First published: September 25, 1984 https://doi.org/10.1002/chin.198439288AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue39September 25, 1984 RelatedInformation

Influence of the metal centers on the pKa of the pyrrole hydrogen of imidazole complexes of (NH3)53+, M(III) = Co(III), Rh(III), Ir(III), Ru(III)

On etudie le PK a , et l'influence de la temperature, pour la deprotonation du NH du pyrrole de plusieurs imidazoles coordinnees a (NH 3 ) 5 M 3+ avec M=Co, Rh, Ir ou Ru

Crystal structure of the mono-lactim ether of a bilatriene- abc derivative at 101 k

The crystal structure of (Z,Z,Z)-19, 24-dihydro-1-methoxy-19-oxo-2,7,13,18-tetramethyl-3,8,12, 17-tetraethyl-22H-bilin was determined at 101 K by X-ray diffraction methods: space group PĪ, a = 9.532(2), b = 12.189(4), c = 13.984(4)Å, α = 114.83(3),β = 103.56(2), γ = 90.55(1)°, Z = 2 (C 32H 40N 4O 2), D x =1.197 g cm −3. Intensity data were collected up to sin θ/λ= 0.765, which permitted anisotropic refinement of all non-hydrogen atoms and isotropic refinement of all hydrogen atoms. The lactim ether exists as the 22H,24H tautomer in the crystal, and assumes a quasi-helical conformation with a CO ⋯ O-Me distance of 3.94å. Molecular conformation and tautomeric form are discussed in terms of intramolecular hydrogen bonding between pyrrole hydrogen atoms and pyrrolenine nitrogen atoms. The molecular conformation in the crystal shows excellent agreement with the result of previous studies in solution.

Evidence for an Imidazolate-Bridged Fe(II)-Cu(II) Complex in Solution

Two new Cu(II) chelate complexes, Cu(imepH) 2+ and Cu(bidH 2) 2+, have been prepared that contain a titratable pyrrole hydrogen of a coordinated imidazole moiety. The deprotonated species, Cu(imep) + and Cu(bidH) +, have been observed to form imidazolate-bridged complexes with Fe(TIM)(CH 3CN) 2 2+ in 60% CH 3CN:40% CH 3OH (V:V). The presence of binuclear complexes at equilibrium with the monomer species in this solvent is confirmed by the appearance of a new CT band (∼620 nm) and altered electron spin resistance (ESR) spectra for the Cu(II) chelates. The binuclear species are O 2 sensitive; the bridged complexes I = [Fe(TIM)(CH 3CN)(imep)Cu] 3+ and II = [Fe(TIM)(CH 3CN) (bidH)Cu] 3+ are discussed in terms of the Palmer model for the heme a 3-Cu(β) interaction in cytochrome oxidase.

Effect of mixed-ligand complex formation on the ionization of the pyrrole hydrogens of histamine and histidine

Equilibrium studies have been carried out by pH titrimetry to determine the stability constants of the parent complexes of CuII NiII and ZnII with histamine and histidine, and of the mixed-ligand complexes of these with, glycine, ethylenediamine, 4,5-dihydroxybenzene-1,3-disulphonate, and 2,2′-bipyridyl. From titrations in an alkaline medium it is concluded that nickel(II) and zinc(II) ions do not affect the ionization of the pyrrole hydrogen significantly compared to the free ligand, but CuII decreases the relevant pKvalues in the parent complexes by about three orders of magnitude. As a consequence of charge-transfer processes, the deprotonation can also be in-fluenced significantly by the formation of mixed-ligand complexes.

Pyrrole hydrogen ionization of imidazole derivatives in metal ion complexes and carbonic anhydrase.

Zinc ion-induced pyrrole hydrogen ionization from a histidyl residue has recently been suggested as the source of the activity-related deprotonation in carbonic anhydrase (EC 4.2.1.1; carbonate hydro-lyase) occurring at pH 7-8. The results offered to support the hypothesis are shown to be deficient. Examination of the literature reveals no precedent for such a pronounced acidification from pK(a) [unk] 14.2 in imidazole compounds by zinc ion. It is suggested that Zn(II)-induced pyrrole ionizations in imidazoles occur with pK(a) about 13.

The Activity-Related Ionization in Carbonic Anhydrase

The catalytic activity of carbonic anhydrase (EC 4.2.1.1) is linked to the ionization of a group in close proximity to the essential zinc ion. Studies have been undertaken to delineate the ionizations germane to the active-site chelate system. Several imidazole ligand systems were studied in order to approach a representative chelate. The simplest involved the complexation of Zn(II) by imidazole and by N-methylimidazole. As well, two bidentate systems, Zn(II)-4,4'-bis-imidazoylmethane and Co(II)-cyclic-L-histidyl-L-histidine were investigated. It was found that in a species containing metal-bound water and imidazole coordinated by means of the pyridinium nitrogen, the most acidic group was the pyrrole N-H in the imidazole ring. By the use of N-methylimidazole, the pK(a) of a metal-bound water molecule in a tri-imidazole ligand field was found to be 9.1. Noting the preference for labilization of the pyrrole hydrogen, the catalytic features of carbonic anhydrase are reexamined assuming that the pK(enz) is associated with the N-H ionization, and not with the ionization of metal-bound water.

HEADER PART IS MISSING IN SOFT COPY

Summary. The toxicities to Aphis rumicis of certain aliphatic and aromatic amines and of some of the simpler nitrogen‐heterocyclic derivatives have been quantitatively determined. Tetramethylammonium hydrate and chloride are more toxic than the corresponding tetraethylammonium compounds. This is in keeping with the findings of Dale and his co‐workers who have shown that tetramethylammonium has certain physiological effects similar to those of nicotine which are not shown by tetraethylammonium. The aromatic amines, on the whole, show little insecticidal action. Aniline and most of the aliphatic anilines are only slightly toxic to A. rumicis. The substitution of aromatic groups in the amino group of aniline increases toxicity more than the substitution of aliphatic groups. There are interesting relationships in regard to toxicity among these compounds. For example, the following orders of toxicity were noted: Phenylamine (aniline) < diphenylamine > triphenylamine.Phenylamine (aniline) < benzylaniline > dibenzylaniline.Benzylamine < dibenzplamine > tribenzylamine. o‐Nitraniline is one of the most toxic of the aniline derivatives. α‐Naphthylamine is more toxic than aniline. Substitution of various radicals in the amino group of aniline has a greater effect on the toxicity of the resulting compound than substitution of the same radicals in α‐naphthylamine. α‐Naphthylamine derivatives are more toxic than the corresponding β‐derivatives. Among the heterocyclic compounds, nicotine is highly poisonous to A. rumicis. The heterocyclic rings constituting the molecule of nicotine are much less toxic than nicotine itself; pyrrole and pyridine show comparatively slight insecticidal action. The order of toxicity of the simpler N‐heterocyclic compounds runs: Pyrrole < pyridine < picoline < lutidine < quinoline and isoquinoline < acridine. Hydrogenation of pyridine and pyrrole increases their toxicity; piperidine is more toxic than pyridine and pyrrolidine than pyrrole. Benzyl‐pyridine is the most toxic pyridine derivative tested.