MYCOCHRYSONE: II. CARBON SKELETON, PRINCIPAL CHROMOPHORE, AND OXYGEN FUNCTIONS

1959 ◽  
Vol 37 (11) ◽  
pp. 1881-1887 ◽  
Author(s):  
G. Read ◽  
L. C. Vining
Keyword(s):  
Oxygen Atom ◽  
Methyl Ether ◽  
Infrared Spectra ◽  
Carbon Skeleton ◽  
Hydroxyl Oxygen ◽  
Elemental Analyses

A mono-and di-methyl ether and two diacetates of mycochrysone have been prepared. Elemental analyses of these derivatives and of the purified pigment itself are consistent with a revised C20H12O7 formula for mycochrysone.The formation of a leucohexaacetate suggests that the molecule contains two hydroxyl or potential hydroxyl oxygen functions in addition to the quinonoid and phenolic (or enolic) groups already shown to be present. The infrared spectra of mycochrysone and derivatives provide evidence that the remaining oxygen atom is ketonic. The principal chromophore of mycochrysone is related to 8-hydroxy-1,2-naphthoquinone. Hydrogenation experiments indicate that the pigment has a perylene carbon skeleton.

Oxidation of secondary alcohols and ethers by dimethyldioxirane

1999 ◽  
Vol 77 (3) ◽  
pp. 308-312 ◽  
Author(s):  
Alfons L Baumstark ◽  
Franci Kovac ◽  
Pedro C Vasquez
Keyword(s):  
Oxygen Atom ◽  
Methyl Ether ◽  
Radical Pair ◽  
Parent Compound ◽  
Activation Parameters ◽  
Silyl Ether ◽  
Secondary Alcohols ◽  
Benzyl Alcohols ◽  
Oxidation Of Alcohols ◽  
Direct Abstraction

The oxidation of several series of secondary alcohols 2-9, ethers 10-17, and related derivatives 18 and19, by dimethyldioxirane, 1, in acetone at 25°C produced the corresponding ketones in good to excellent yields for all but two cases. (The exceptions: oxidation of 1-methoxy-2-methyl-1-phenylpropane (48%) and 1-methoxy-2,2-dimethyl-1-phenylpropane (24%).) The oxidation of the secondary alcohols was found to yield k2 values that were roughly 10-fold greater than those of the corresponding methyl ethers. The rate constant for oxidation of a silyl ether was slightly lower than that for the corresponding methyl ether while that for the ester derivative was roughly half the value. For oxidation of alcohols and methyl ethers, the k2 values became smaller as the R " series (Me, Et, nPr, iPr, and tBu) increased in steric bulk (ρ* = 1.7; r = 0.998 and ρ* = 3.2; r = 0.95, respectively). The Hammett study for the oxidation of the methyl ethers of α-methyl-p-benzyl alcohols (10, 20-25) yielded a ρ value of -0.74. The activation parameters for oxidation of the parent compound of the ether series (1-methoxy-1-phenylethane) were ΔH‡ = 14.8 ± 0.5 kcal/mol, ΔS‡ = -21.9 eu, ΔG‡ = 21.3 kcal/mol, k2 (25°C) = 1.6 × 10-3 M-1 s-1. The mechanistic aspects of the oxidation are discussed in relation to two mechanistic extremes: (a) direct insertion of the oxygen atom into the C—H bond and (b) direct abstraction of the H by dimethyldioxirane to yield a caged-radical pair, with subsequent coupling to hemi-ketal intermediates that fragment to yield acetone, alcohol or water, and ketone as the final products.Key words: dimethyldioxirane, oxidation.

INFRARED SPECTRA OF 2,6-DIMETHYL-4-PYRONE COMPLEXES

1961 ◽  
Vol 39 (6) ◽  
pp. 1184-1189 ◽  
Author(s):  
Denys Cook
Keyword(s):  
Complex Formation ◽  
Oxygen Atom ◽  
Carbonyl Group ◽  
Lewis Acid ◽  
Frequency Band ◽  
Infrared Spectra ◽  
Donor Site ◽  
Carbonyl Oxygen ◽  
Acid Strength ◽  
Group A

The infrared spectra of 2,6-dimethyl-4-pyrone in solution, and in complexes with HgCl2, ZnCl2, BF3, SbCl5, and HBr have been recorded. A band at 1639 cm−1 in the free pyrone moves to progressively lower frequencies in the complexes as the Lewis acid strength increases, identifying this band as the carbonyl stretching frequency and the donor site as the carbonyl group. A higher-frequency band, at 1678 cm−1 in the free pyrone, moves to lower frequency on complex formation, but to a much smaller extent, and is to be identified with a stretching mode of the ring. The site of protonation in 2,6-dimethyl-4-pyrone salts has been unequivocally shown to be the carbonyl oxygen atom.

Raman and infrared spectra, conformational stability, barrier to internal rotation, and ab initio calculations for 1,1-dichloromethyl methyl ether

1994 ◽  
Vol 25 (9) ◽  
pp. 747-760 ◽  
Author(s):  
Howard D. Stidham ◽  
A. Charla Vlaservich ◽  
David Y. Hsu ◽  
Gamil A. Guirgis ◽  
J. R. Durig
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Internal Rotation ◽  
Methyl Ether ◽  
Infrared Spectra ◽  
Conformational Stability

The coordination of β-amino ketoximes with divalent iron, cobalt, nickel and zinc

1978 ◽  
Vol 31 (11) ◽  
pp. 2409 ◽  
Author(s):  
HKJ Powell ◽  
JM Russell
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Stability Constant ◽  
Methyl Ether ◽  
Infrared Spectra ◽  
Iron Cobalt ◽  
Divalent Iron ◽  
Cobalt Nickel ◽  
Stability Order ◽  
The Stability

The iron(II), nickel(II) and zinc(II) complexes of the diamine dioxime ligand 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dioxime (H2dddo) and the cobalt(II), nickel(II) and zinc(II) complexes of its O-methyl ether (Hddmo) have been studied potentiometrically at 25°C, I 0.10M NaCl. Stability constant data are compared with those obtained for the copper(II) and cobalt(II) complexes of H2dddo and the copper(II) complexes of Hddmo. H2dddo coordinates in the oxime-oximato form [M(Hdddo)]+ with iron(II), cobalt(II), nickel(II) and zinc(II) Hddmo forms complexes with the ligand coordinated in the oxime form [M(Hddmo)]2+ and the oximato form [M(ddmo)]+. The complexes [Zn(Hddmo)2]2+, [Zn(Hddmo)(ddmo)]+ and [Co(ddmo)(OH)] were also characterized in aqueous solution. The stability order FeII < CoII < NiII < CuII > ZnII was observed for the formation of 1 : 1 complexes with the ligands Hdddo- (log K = 8.8, 11.7, 15.2, 23.3, 12.0 for Fe to Zn respectively) and Hddmo (5.7, 6.6, 12.1, 5.3 for Co to Zn). The infrared spectra of the complexes [Ni(Hdddo)] ClO4,H2O and [Zn(Hdddo)] ClO4 are discussed in terms of oxime-oximato hydrogen bonding.

FURTHER EVIDENCE FOR CYCLIC MONOMERS IN HEATED LINSEED OIL

1961 ◽  
Vol 39 (10) ◽  
pp. 1906-1914 ◽  
Author(s):  
A. G. McInnes ◽  
F. P. Cooper ◽  
J. A. MacDonald
Keyword(s):  
Double Bond ◽  
Infrared Spectra ◽  
Chemical Structure ◽  
Linseed Oil ◽  
Carbon Skeleton ◽  
Side Chain ◽  
Partition Chromatography

The distillable esters of heated linseed oil contain a fraction, designated NAFD, which fails to form an adduct with urea. NAFD itself has now been separated into three fractions by gas-liquid partition chromatography. The chemical structure of these component esters was investigated by means of their infrared spectra and by analysis of the products obtained on oxidation of the esters with periodate–permanganate. It is concluded that all the components have the same carbon skeleton, namely, 1-propyl-2-alkenecarboxycyclohexene, but differ in the position of the double bond in the side chain.

scholarly journals Tetranuclear Hetro-Metal [MnIII2NiII2] Complexes Involving Defective Double-Cubane Structure: Synthesis, Crystal Structures, and Magnetic Properties

2019 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Yuki Suemitsu ◽  
Ryuji Matsunaga ◽  
Takashi Toyofuku ◽  
Yasunori Yamada ◽  
Masahiro Mikuriya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Crystal Structures ◽  
Infrared Spectra ◽  
Magnetic Measurements ◽  
Metal Core ◽  
X Ray ◽  
Structure Synthesis ◽  
Elemental Analyses

Tetranuclear hetero-metal MnIII2NiII2 complexes, [Mn2Ni2(L)4(OAc)2] (1) and [Mn2Ni2(L)4(NO3)2] (2) [H2L = N-(2-hydroxymethylphenyl)-5,6-benzosalicylideneimine], have been synthesized and characterized by X-ray crystal structure analyses, infrared spectra, and elemental analyses. The structure analyses revealed that the complexes have a defective double-cubane metal core connected by μ3-alkoxo bridges. Complexes consist of two bis-μ-alkoxo bridged MnIIINiII heteronuclear units making a dimer-of-dimers structure. The double-cubane cores are significantly distorted due to an effect of syn–syn mode acetato or nitrato bridges. Magnetic measurements indicate that weak antiferromagnetic interactions (Mn-Ni = −0.66 ~ −4.19 cm–1) are dominant in the hetero-metal core.

COORDINATION COMPLEXES OF TITANIUM (IV) HALIDES: III. PREPARATION AND INFRARED SPECTRA OF THE COMPLEXES OF TITANIUM TETRACHLORIDE WITH UREA, THIOUREA, AND SOME OF THEIR DERIVATIVES

1962 ◽  
Vol 40 (12) ◽  
pp. 2234-2242 ◽  
Author(s):  
Roland Rivest
Keyword(s):  
Molecular Weight ◽  
Oxygen Atom ◽  
Infrared Spectra ◽  
Titanium Tetrachloride ◽  
Coordination Complexes ◽  
Dinuclear Complexes ◽  
Derivatives Of

The following coordination complexes of titanium (IV) have been prepared: TiCl4•2CO(NH2)2, TiCl4•CO(NHCH3)2, TiCl4•2CO(NHCH3)2, 2TiCl4•2NH2CON(C6H5)2, 2TiCl4•2CO(NHC6H5)2 TiCl4•2CS(NH2)2, 2TiCl4•CS(NHC2H5)2, 2TiCl4•NH2CSN(C6H5)2, and 2TiCl4•CS(NHC6H5)2; their infrared spectra have been measured and their molecular weight determined. For urea and its derivatives the coordination to titanium (IV) is always through the oxygen atom. The phenyl derivatives of urea led to dinuclear complexes which were best explained by assuming halogen bridging between the titanium atoms. Thiourea and its derivatives gave complexes in which coordination occurred through one of the nitrogens in the case of thiourea and through both nitrogens in the case of the derivatives. Halogen bridging was again assumed to explain the formation of the dinuclear complexes.

scholarly journals X-ray structure of cytidine-5′-O-dimethylphosphate. Novel stacking between the ribosyl O(2′) hydroxyl oxygen atom and the base

1984 ◽  
Vol 12 (17) ◽  
pp. 6813-6825 ◽  
Author(s):  
Richard G. Brennan ◽  
Norman S. Kondo ◽  
Muttaiya Sundaralingam
Keyword(s):  
Oxygen Atom ◽  
X Ray ◽  
Hydroxyl Oxygen ◽  
Hydroxyl Oxygen Atom

Conformation of dimethylaminoethanol, its methyl ether and of the corresponding trimethylammonium iodides. NMR and vibrational spectra

1987 ◽  
Vol 52 (5) ◽  
pp. 1256-1271 ◽  
Author(s):  
Jan Štokr ◽  
Bohdan Schneider ◽  
Danica Doskočilová ◽  
Stanislav Ševčík ◽  
Martin Přádný
Keyword(s):  
Methyl Ether ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Crystalline State ◽  
Nmr Spectra ◽  
H Nmr ◽  
Liquid States ◽  
Fully Coupled ◽  
Solid And Liquid States ◽  
C Nmr

By analysis of fully coupled 13C NMR spectra and of 1H NMR spectra of dimethylaminoethanol, its methyl ether, and of the corresponding trimethylammonium iodides, populations of isomers generated by rotation about the bonds N-CH2, CH2-CH2, and CH2-O in these compounds in solution were determined. By analysis of Raman and infrared spectra of these compounds in the solid and liquid states it was found that in the crystalline state these compounds form structures with parallel N-CH3 and O-CH2 bonds, which are also preferred in the liquid state.

scholarly journals Synthesis and characterization of novel oxo-bridged, trinuclear mixed-metal complexes of Cr(III) and Fe(III)

2009 ◽  
Vol 74 (4) ◽  
pp. 401-406 ◽  
Author(s):  
Mohammad Yazdanbakhsh ◽  
Iman Khosravi ◽  
Haman Tavakkoli
Keyword(s):  
Metal Complex ◽  
Infrared Spectra ◽  
Carboxylate Ligand ◽  
Synthesis And Characterization ◽  
Chlorobenzoic Acid ◽  
Mixed Metal ◽  
Elemental Analyses ◽  
New Type ◽  
Mixed Metal Complexes

Two new heterotrinuclear p-chlorobenzoates, [Fe2CrO(C7H4O2Cl)6(py)3]NO3 (1) and [Cr2FeO(C7H4O2Cl)6(py)3]NO3 (2) were prepared as nitrate salts and characterized by elemental analyses (CHN), spectroscopic (infrared, electronic) studies and atomic absorption spectroscopy. These complexes are a new type of oxo-bridged mixed-metal complex in which the carboxylate ligand is p-chlorobenzoic acid. Bridging coordination modes for the carboxylates were indicated by the presence of ?asym (M2M'O) vibrations in the infrared spectra.

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