Phenol Fragments Research Articles

Molecular design and QSAR study of low acute toxicity biocides with 4,4′-dimorpholyl-methane core obtained by microwave-assisted synthesis

The solventless microwave-assisted synthesis of aldehydes (1a, 2b–h) and morpholine (3) in 1 : 2 (aldehyde : morpholine) ratio yielded eight 4,4′-dimorpholyl-methanes (4a–4h), which were thoroughly characterized through FT-IR, 1H, 13C and 2D NMR, confirming structures of type 4. The described compounds are dimorpholino-methane (4a), 2-(dimorpholinomethyl)-phenol (4b), 4-bromo-2-(dimorpholinomethyl)-phenol (4c), 2,4-di-tert-butyl-6-(dimorpholinomethyl)-phenol (4d), 4,4′-(pyridin-2-ylmethylene)-dimorpholine (4e), 4,4′-((4-iso-propylphenyl)methylene)-dimorpholine (4f), 4,4′-(naphthalen-1-ylmethylene)-dimorpholine (4g) and 4,4′-(pyren-1-ylmethylene)-dimorpholine (4h). Additionally, single crystal X-ray diffraction analysis for 4b, 4c, 4d and 4e derivatives was accomplished showing interesting geometrical features. The obtained 4,4′-dimorpholyl-methanes were subjected for two biological tests, (i) acute toxicity, related to Photobacterium phosphoreum (Vibrio fischeri), and (ii) biocidal activities, determined for B. subtilis, E. coli and Ps. fluorescence strains. The results show that 4a–h compounds have varying degrees of toxicity, classified as 4a, 4b, 4c, 4e and 4f as slightly to moderately toxic agents, 4g and 4h as highly toxic chemicals, and 4d as an extremely toxic compound. Besides, the biocidal activities, which is controlled mainly by the substituent directly bonded to the methinic bridge (named C5, which originally is the carbon atom of the aldehyde functionality), have shown varying degrees of inhibitory effects on the growth of selected strains, depending on the chemical structure of 4a–h. A QSAR study was developed, and quantum-chemical parameters of 4a–h were obtained with the DFT approach at the B3LYP/6-311G(d) level of theory in the gas phase. Hence ten molecular descriptors were determined, being EHOMO, ELUMO, GAP, C5 Mulliken atomic charge (ACMulliken), C5 atomic charge of NBO (ACNBO), dipolar moment (μ), molecular hydrophobicity as log P, molecular volume (Vol), electrostatic potential (ESP) and δ13C(C5), all of them being typical determinants of biological activities in other, different or related, molecular systems. A linear combination from three to six molecular descriptors was chosen as a multivariate model to achieve correlations in order to relate them to their acute toxicity and understand the obtained trend. Three sets of descriptors accomplished the statistical goal, and through an identity analysis the conserved descriptors in these three series are log P, the ESP and the δ13C(C5), which seemed to be the tracking variables in the system. To a lesser extent, the frontier orbitals and their relations (HOMO, LUMO and GAP) are also present within the correlations. The phenol-bearing structures (4b, 4c and 4d, derived from salicylidenes) are best tuned within these variables since the substitution in the phenol fragment both governs the toxicity and the biocidal potency. Finally, we can guarantee that the best candidates in this series are 4a, 4b and 4c, because diminished toxicity and preserved biocidal potency were obtained at the same time. A more hydrophobic substitution (4d) extremely increases the Vibrio fischeri toxicity, ruling out its application. Through the full analysis presented in this piece of work it can be stated that selected prototypes could be used in industrial facilities, particularly in the petroleum industry, as a new generation of ecological chemical products.

4-Hydroxy-N′-(2-hydroxybenzylidene)benzohydrazide

In the title mol­ecule, C14H12N2O3, the –N—C(=O)– and 2-(imino­meth­yl)phenol fragments are almost coplanar, with an r.m.s. deviation of 0.0308 A. The dihedral angle between the mean planes of p-phenol and N′-(2-hydroxy­benzyl­idene)formohydrazide is 20.95 (7)°. Inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into zigzag chains running along the b axis. Weak inter­molecular N—H⋯O hydrogen bonds stabilize these chains into a three-dimensional packing.

22-Hydroxybenziporphyrin: Switching of Antiaromaticity by Phenol−Keto Tautomerization

22-hydroxybenziporphyrin, a porphyrin analogue containing a phenol moiety, has been shown to exist as an equilibrium mixture of two distinctly different tautomers. One of them actually contains the hydroxy group and shows the local [6]annulene aromaticity in the phenol fragment. The other tautomer contains a keto group and exhibits a [20]annulenoid structure characterized by macrocyclic antiaromaticity. The tautomerization process has been investigated in detail using variable-temperature 1H NMR spectroscopy. The process is very fast, with an estimated activation energy of ca. 30 kJ/mol. Further insight into the energetics of the tautomerization is obtained from density functional (DFT) calculations. Surprisingly, the estimated energy of the antiaromatic keto species is 3-5 kcal/mol lower than the energy of the phenolic tautomer. The geometric and magnetic manifestations of aromaticity and antiaromaticity in the two tautomers are probed using a number of computational devices, including Wiberg bond indices, resonace weights derived from the harmonic oscillator model, and nucleus-independent chemical shifts. It is shown that mixing of phenolic and keto contributions in both tautomers is stronger than that in related tautomers of phenol. This effect is caused by extensive conjugation with the tripyrrolic unit of 22-hydroxybenziporphyrin and, to a lesser extent, by intramolecular hydrogen bonding.

New oligomeric thioether antioxidants for polymers

Polyfunctional oligomeric antioxidants with a sterically hindered phenolic fragment were prepared. The influence of these antioxidants on oxidation and degradation of SKI-3 rubber was analyzed.

1-(2-Hydroxyphenyl)ethanone benzoylhydrazone

In the title compound, the planes of the phen­yl and 2-(1-imino­eth­yl)phenol fragments form dihedral angles of 28.18 (11) and 28.51 (11)°, respectively, with the central –N—C(=O)– fragment. The mol­ecule is stabilized by inter­molecular N—H⋯O hydrogen bonds, which form a one-dimensional chain parallel to the a axis.

Oleic acid peroxidation in the presence of metallo-porphyrins

The influence of free bases of meso-tetrakis(3,5-di-tert-butyl-4-hydroxy-phenyl)porphyrins and meso-tetraphenylporphyrins and their complexes of Co , Ni , Cu , Pt upon the radical chain oxidation of oleic acid as model substrates for lipid peroxidation has been studied. It was shown that the introduction of the antioxidative phenolic fragment into the porphyrin ring leads to the dual activity of phenolic porphyrins when compared with their tetraphenyl substituted analogues in substrate oxidation. Free base phenolic porphyrins and their nickel, copper, platinum complexes demonstrate acute inhibitory effect upon oleic acid peroxidation due to the key role of 2,6-di-tert-butylphenol moities, whereas cobalt porphyrin exhibits dual activity associated with the presence of both the redox active metal center and phenolic group.

Core-modified porphyrin incorporating a phenolate donor. Characterization of Pd(II), Ni(II), Zn(II), Cd(II), and Fe(III) complexes.

Coordinating properties of acetoxybenziporphyrin, (TPBPOAc)H, have been investigated for a number of metal ions. Insertion of Ni, Pd, and Fe results in the cleavage of the acetoxy group leading to complexes (TPBPO)Ni(II), (TPBPO)Pd(II), and (TPBPO)Fe(III)X containing a M-O bond. No cleavage is observed with Zn(II) and Cd(II), which form complexes (TPBPOAc)M(II)Cl, where M = Zn, Cd. (TPBPO)Ni(II) can also be obtained from the dication of hydroxybenziporphyrin, [(TPBPOH)H(3)]Cl(2), which is prepared by acid hydrolysis of the acetoxy compound. The diamagnetic (TPBPO)Ni(II) can be transformed into the paramagnetic (TPBPOAc)Ni(II)Cl in a reaction with acetyl chloride. X-ray structures have been determined for (TPBPO)Pd(II) and (TPBPOAc)Zn(II)Cl. In the palladium species, the phenolate moiety forms a strong bond to the Pd ion and an unusual interaction geometry is observed, enforced by the macrocyclic environment. Association of a TFA molecule to the phenolic oxygen does not cause significant structural changes in the (TPBPO)Pd(II) molecule. In (TPBPOAc)Zn(II)Cl, the metal ion weakly interacts with the phenolic fragment. The paramagnetic Fe(III) complexes, (TPBPO)Fe(III)X, have been investigated with (1)H NMR spectroscopy. The observed spectral patterns are consistent with the presence of a high-spin Fe(III) center and pi delocalization of spin density onto the phenoxide fragment. Each of the compounds (TPBPO)Fe(III)X exists in solution as a mixture of two isomers, which for X = I are shown to remain in a temperature-dependent equilibrium. The observed isomerism results from two nonequivalent orientations of the axial halide with respect to the puckered macrocyclic ring.

2-(2,1-benzoxazol-3-yl)-3,5-dimethoxyphenol and 3-phenyl-2,1-benzoxazole.

The title compounds, C(15)H(13)NO(4), (I), and C(13)H(9)NO, (II), are produced, along with the corresponding anilines, by the reduction of the appropriate o-nitrobenzophenones. In (I), the planar benzisoxazole and phenol fragments are tilted relative to one another by a rotation of 53.02 (14) degrees about the bond joining them, and the molecules are linked into chains by phenol O--H...N and phenyl C--H...O(oxazole) hydrogen bonds. The cell of (II) (space group I2/c) contains eight molecules in general positions, four more in the 2b sites, with twofold axial symmetry that induces a degree of disorder, and a further four as centrosymmetric pairs of complete molecules, each with an occupancy of one-half. The relative tilt of the planar fragments varies slightly from one molecule to another but is much less than that in (I), ranging from 8.8 (8) to 12.58 (15) degrees.

Effect of arylamines containing 3,5-di-tert-butyl-4-hydroxyphenyl fragment on stability of polypropylene, isoprene rubber, and thermoelastoplastics derived from them

The effect of arylamines containing a sterically hindered phenolic fragment on the resistance of polypropylene, synthetic isoprene rubber, and thermoelastoplastics derived from them to oxidative and thermomechanical degradation was studied in relation to the structure of the additives.

Electrochemical reduction and oxidation of fullerenopyrrolidines* and the ESR spectra of paramagnetic intermediates

Electroreduction and electrooxidation of monosubstituted N-methyl[60]fullerenopyrrolidines were studied by cyclic voltammetry and potentiostatic microelectrolysis in the cavity of an ESR spectrometer. Stepwise reversible transfer of three electrons to the fullerenopyrrolidine molecule results in the formation of stable radical anions (according to ESR, g = 2.0000, ΔH = 0.8 G), dianions, and radical trianions (according to ESR, g = 2.0015, ΔH = 1.5 G). The reduction potentials vary over narrow limits depending on the nature of the substituents in the pyrrolidine fragment of the compounds. Electrooxidation is irreversible and occurs in either one or two steps. For compounds containing the aniline, indole, or phenol fragment, the first step is associated with oxidation of these fragments and only after that, is the fullerenopyrrolidine core oxidized. Oxidation of the pyrrolidine fragment is substantially more difficult than that of tertiary amines.

Fulleropyrrolidine-containing sterically hindered phenol. Synthesis, structure, and properties

Fulleropyrrolidine containing a sterically hindered phenolic fragment was synthesized by the reaction of fullerene C60 with N-methylglycine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde. Electrochemical reduction of fulleropyrrolidine-containing phenol 1 and the corresponding phenoxide ion proceeded stepwise to form stable radical anions, dianions, and trianions. The radical anion (g = 2.0000) and the phenoxyl radical (g = 2.0045) obtained by chemical oxidation with lead dioxide were identified by ESR spectroscopy. The electron affinity of fulleropyrrolidine was estimated at 2.58 eV. For the phenoxide ion, the electrochemical gap was determined (ΔE = EIox – EIred = 0.47 V). The heats of formation and the energies of the frontier orbitals of fulleropyrrolidine and its transformation products were evaluated by the PM3 method.

X-ray and NMR investigation of 25,27-dihydroxy-26,28-bis(diethoxyphosphoryloxy)-tert-butylcalix[4]arene in the1,2-alternate conformation

The crystal structure of 25,27-dihydroxy-26,28-bis(diethoxyphosphoryloxy)-tert-butylcalix[4]arene (1) (hexane solvate, 1:1) was determined by x-ray crystallography. The crystal data are P21/n, a = 12.652(1) Å, b = 12.564(2) Å, c = 18.781(4) Å, β = 105.56(1)°, V = 2876.0(8) Å3, Z = 2. In this complex the molecule adopts a 1,2-alternate conformation. Both the calixarene and hexane molecules are centrosymmetric. The phenol units in the asymmetric part of the calix are inclined with respect to the main macrocyclic plane by 115.46(6)° and 128.01(7)° for the phosphorylated and the non-phosphorylated ring, respectively. Self-inclusion of the ethyl chains in the half-cavities is observed. One intramolecular O—H…O and several intermolecular C—H…O hydrogen bonds are present. In the 1H NMR spectrum one average AX spin system for methylene bridge protons can be interpreted as fast (on the NMR time-scale) interconversion of non-phosphorylated phenol fragments. © 1998 John Wiley & Sons, Ltd.

ChemInform Abstract: Synthesis and Properties of sym‐Triazine Derivatives. Part 12. Synthesis of 2,4‐Bis(trichloromethyl)‐6‐substituted sym‐Triazines Containing Sterically Hindered Phenol Fragments.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

1,2-Disubstituted imidazolines with heterocyclic fragments as antimicrobial additives for jet fuels

The most promising and convenient method for protecting hydrocarbon fuels against damage by microorganisms is the use of antimicrobial additives that are effective for extended periods in the storage and transportation of fuels. Imidazoline derivatives manifest high biocidal activities in petroleum distillate fuels, with the activity depending considerably on the nature and structure of the radicals linked to the imidazoline ring. One example of a highly effective additive is AID 9-12, the basic components of which are 1,2-disubstituted imidazolines obtained by the condensation of polyethylenepolyamines with an n-C{sub 9} - C{sub 12} fraction of synthetic fatty acids. At low concentrations in jet fuels, this additive exhibits high activities against microbial damage without having any adverse effects on the physicochemical or service properties of the fuels. Also effective as antimicrobial additives for jet fuels are imidazolines with sterically hindered phenol fragments or with naphthyl or benzyl radicals. In our search for effective antimicrobial additives, we have investigated a series of 1,2-disubstituted imidazolines with heterocyclic fragments. In this paper, we report the results of our investigation.

Effect of azoles andsym-triazines with hindered phenol fragments on protective properties of turbine oils

In gas compressors operating on natural gas containing hydrogen sulfide, considerable amounts of hydrogen sulfide may get into the lubricating oil, as the hydrogen sulfide is quite oil-soluble. When this happens, the metals and alloys that are in contact with hydrogen sulfide-saturated oils are subject to severe hydrogen sulfide corrosion. The corrosion products, if they enter the oil, render it unsuitable for further service. The most effective means for protecting gas field equipment against hydrogen sulfide corrosion is the use of corrosion inhibitors in the oil. There is considerable urgency in this search for suitable corrosion inhibitors having good compatibility with lube oils. Heterocyclic nitrogen compounds are of much interest. As a rule, they are multifunctional: They manifest antioxidant, anticorrosion, antiwear, and antiscoring properties. In searching for prospective inhibitors of hydrogen sulfide corrosion, we have investigated previously synthesized azoles and sym-trizines containing hindered phenol fragments. In this paper, we present the results of our investigation.

ChemInform Abstract: Synthesis and Properties of sym‐Triazine Derivatives. Part 10. Synthesis of 2,4‐Diamino‐sym‐triazines (V), Containing Sterically Hindered Phenol Fragments.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Salts of acyl halides and 3, 5-di-tert-butyl-4-hydroxy-N, N-dimethylbenzylamine in benzylation reactions

The interaction of 3, 5-di-tert-butyl-4-hydroxy-N, N-dimethylbenzyiamine with various acyl halides has been studied. The N-acyl quaternary ammonium salts obtained can be used to introduce a sterically hindered phenol fragment into organic compounds containing an active methylene group.

Total synthesis of the ionophore antibiotic CP-61,405 (routiennocin)

The total synthesis of the spiroketal ionophore antibiotic routiennocin 1 (CP-61,405) employing π-allyltricarbonyl iron lactone complexes is described. These complexes were used as precursors for the preparation of substituted 2-phenylsulphonyl pyrans which, in turn, were coupled with iodoacetonides to afford spiroketals. Elaboration of the spiroketals by tetra- n-propylammonium perruthenate (TPAP) oxidation and coupling with 2-lithio-1-[β-(trimethylsilyl)ethoxymethyl] pyrrole followed by further oxidation, deprotection, oxidation and benzoxazole formation afforded the natural product. The preparation of the amino phenol fragment necessary for benzoxazole formation involved a novel amination procedure using benzeneselenenic anhydride and hexamethyldisilazane followed by samarium diiodide reduction.

A theoretical conformation analysis for 4-(4?-hydroxybenzylidene)-2,5-cyclohexadien-1-one

Atom-atom potentials have been used with complete geometrical optimization in calculations on the conformations of 4-(4'-hydroxybenzylidene)-2,5-cyclohexadien-1-one. The optimal conformation corresponds to a torsion angle between the plane phenol and p-quinonemethide fragments. Internal rotation involves overcoming barriers of 2.6 kJ/mole and 18.7 kJ/mole. It is suggested that the ionic and radical forms of this compound are also nonplanar and therefore belong to the class of systems with coupled conformational-electronic rearrangements.

ChemInform Abstract: New Derivatives of Imidazoline‐3‐oxide and Thiazoline with 2,6‐Dialkylphenol Fragments.

AbstractDie aus 2,6‐Dialkylphenolen (I) durch Umsetzung mit Methylvinylketon (II) hergestellten 4‐Arylbutanone (III) cyclisieren mit Amino‐oximen (IV) zu Imidazolin‐oxiden (V).