Aromatic Dihydroxy Compounds Research Articles

Rate coefficients for the gas‐phase reaction of OH radicals with selected dihydroxybenzenes and benzoquinones

Rate coefficients have been determined for the gas-phase reaction of the hydroxyl (OH) radical with the aromatic dihydroxy compounds 1,2-dihydroxybenzene, 1,2-dihydroxy-3-methylbenzene and 1,2-dihydroxy-4-methylbenzene as well as the two benzoquinone derivatives 1,4-benzoquinone and methyl-1,4-benzoquinone. The measurements were performed in a large-volume photoreactor at (300 ± 5) K in 760 Torr of synthetic air using the relative kinetic technique. The rate coefficients obtained using isoprene, 1,3-butadiene, and E-2-butene as reference hydrocarbons are kOH(1,2-dihydroxybenzene) = (1.04 ± 0.21) × 10−10 cm3 s−1, kOH(1,2-dihydroxy-3-methylbenzene) = (2.05 ± 0.43) × 10−10 cm3 s−1, kOH(1,2-dihydroxy-4-methylbenzene) = (1.56 ± 0.33) × 10−10 cm3 s−1, kOH(1,4-benzoquinone) = (4.6 ± 0.9) × 10−12 cm3 s−1, kOH(methyl-1,4-benzoquinone) = (2.35 ± 0.47) × 10−11 cm3 s−1. This study represents the first determination of OH radical reaction-rate coefficients for these compounds. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 696–702, 2000

Transglycosylation by Streptococcus mutans GS-5 glucosyltransferase-D: acceptor specificity and engineering of reaction conditions.

The acceptor specificity of Streptococcus mutans GS-5 glucosyltransferase-D (GTF-D) was studied, particular the specificity toward non-saccharide compounds. Dihydroxy aromatic compounds like catechol, 4-methylcatechol, and 3-methoxycatechol were glycosylated by GTF-D with a high efficiency. Transglycosylation yields were 65%, 50%, and 75%, respectively, using 40 mM acceptor and 200 mM sucrose as glucosyl donor. 3-Methoxylcatchol was also glycosylated, though at a significantly lower rate. A number of other aromatic compounds such as phenol, 2-hydroxybenzaldehyde, 1,3-dihydroxybenzene, and 1, 2-phenylethanediol were not glycosylated by GTF-D. Consequently GTF-D aromatic acceptors appear to require two adjacent aromatic hydroxyl groups. In order to facilitate the transglycosylation of less water-soluble acceptors the use of various water miscible organic solvents (cosolvents) was studied. The flavonoid catechin was used as a model acceptor. Bis-2-methoxyethyl ether (MEE) was selected as a useful cosolvent. In the presence of 15% (v/v) MEE the specific catechin transglucosylation activity was increased 4-fold due to a 12-fold increase in catechin solubility. MEE (10-30% v/v) could also be used to allow the transglycosylation of catechol, 4-methylcatechol, and 3-methoxycatechol at concentrations (200 mM) otherwise inhibiting GTF-D transglycosylation activity.

Ladder type polymers from dihydroxyaromatic compounds and dialdehydes

Ladder type polymers from dihydroxyaromatic compounds and dialdehydes

Ladder type polymers from dihydroxyaromatic compounds and dialdehydes

Ladder polymers were synthesized by reaction of dihydroxynaphthalene and bisphenols with malondialdehyde and glutardialdehyde. Differential scanning calorimetry and thermogravimetric analysis were used to determine the thermal behaviour of the polymers, and conductivities of two representative polymers were measured. Ladder polymers with higher molecular weights showed better thermal resistance.

Synthesis of bis(hydroxyethyl ether)s of aromatic dihydroxy compounds and poly(ether-carbonate)s with bisphenol A

A new class of copoly(ether-carbonate)s was synthesized using a melt polycondensation reaction of the bis(hydroxyethyl ether) of bisphenol A with bisphenols and diphenyl carbonate. Copolymers with a wide range of Tg values (62–140°C) were obtained. The copolymer structures were established by 1H NMR, 13C NMR and FTIR investigations. © 1998 Society of Chemical Industry

Length of Phenolic Strings in Dissolution Inhibition Resists

We have determined the inhibition strength of a group of difunctional naphthalene-1-sulfonic acid esters. In these structures the sulfonic acid groups were placed at increasing distances from each other by using aromatic dihydroxy compounds as spacers. At short distances the inhibition factors of the difunctional compounds are much smaller than the sum of the inhibition factors of the monofunctional sulfonic acid groups, and we interpret this as the result of interference between the phenolic strings emanating from the S=O dipoles of the sulfonic acid moieties. By systematically increasing the distance between the sulfonic acid groups, we were able to determine the critical distance at which their strings no longer influence each other. We believe that in this way we have found the radius of gyration and hence the length of the undisturbed strings.

31 Redox cycling by cytochrome P-450

The cytochrome from Bacillus megaterium (P-450 BM-3) is a catalytically self-sufficient haem-thiolate enzyme consisting of a haem domain which is the site for substrate binding and a reductase domain containing an NADPH binding site [l], and acting as a source of electrons. The two domains have significant sequence similarities with the corresponding separate eukaryotic proteins. Expression systems for intact P-450 BM-3 and for its individual domains are available [Z]. P-450 BM-3 may be a convenient analogue for the less readily available mammalian drug-metabolising cytochrome P-450s. It hydoxylates long-chain fatty acids [3], and we were interested in identifying other compounds that it would accept as substrate. Dihydroxyaromatic compounds can appear in the biotransformation of quinones, which are widely distributed [4], and are used as antitumour and cytostatic agents [5]. We measured binding and catalytic activity for the interaction of 2,3-dihydroxynaphthalene with intact enzyme and with reductase domain alone (Table 1). NADPH consumption and peroxide production show similar activities for the two proteins. We assume that quinone is formed and is then subsequently reduced directly by the reductase, with concomitant oxidation of NADPH. Redox cycling by cytochrome P-450

Selective oxidation of phenols using copper complexes encapsulated in zeolites

The oxidation and hydroxylation of phenols to dihydroxy aromatic compounds have been investigated using phthalocyanines and substituted (chloro- and nitro-) phthalocyanines of copper encapsulated in zeolites (X and Y). H 2O 2 has been used as oxidant. At ambient conditions, the encapsulated copper chloro- and nitro phthalocyanine complexes, unlike their unsubstituted analogs, are able to oxidise, selectively, phenol to catechol and hydroquinone. The catalytic efficiency (turnover number) of the copper atoms are higher in the encapsulated state compared to that in the “neat” complex. The solid catalysts have been characterised by IR, UV, ESR and ESCA spectroscopy. The influence of various process parameters (like temperature, reaction time, substrate/oxidant ratio, catalyst weight etc.) on the conversion and product distribution is also illustrated and discussed.

Organophosphorus compounds XV. The reaction of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's Reagent) with aromatic dihydroxy compounds. Simple new route to 1,3,2-dioxaphospholane-2-sulfide

2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's Reagent) and its p-phenoxy derivative react with o-dihydroxybenzene derivatives, dihydroxy naphthalene and 2,2-dihydroxybiphenyl in toluene at reflux temperature to give 1,3,2-dioxaphospholane-2-sulfide derivatives, 3a–f, 8a,b and 11a,b respectively. The structure of the products has established either chemically using methanolysis and methylation or spectroscopically. Also, analytical data has been used. A mechanistic considerations on the formation of the above products are discussed.

Organosubstituierte 1,6‐Dioxa‐2‐sila‐5‐bora‐3‐cycloalkene – Herstellung und Charakterisierung

Organosubstituted 1,6‐Dioxa‐2‐sila‐5‐bora‐3‐cycloalkenes – Preparation and Characterisation1)The cis‐alkenes ROSi(CH3)2C(R)  C(C2H5)B(C2H5)OR (R  CH3: 11; C2H5: 12; C6H5: 13) are prepared from CH3NSI[CH3)2C(R)C(C2H5)BC2H5 [R  CH3: A; R  C(CH3)  CH2: B] with the monohydroxy compounds ROH (R  CH3, C2H5, C6H5). A or B react with aliphatic dihydroxy compounds HOR′OH [R′  CH2CH2: 1; CH(CH3)CH2: 2; CH(CH3)CH(CH3): 3; C(CH3)2C(CH3)2: 4; (CH2)3: 5; (CH2)4: 6] to give 8‐, 9‐, and 10‐membered ring compounds OSi(CH3)2C(R)  C(C2H5)OR′ [15a,b, 16/16′, meso/rac‐17a, D‐17a,b, 18, 19, (20)n]. A is initially cleaved at the SiN bond with formation of 14 Compound 15a crystallises as the 16‐membered (15a)2 [X‐ray structure analysis). The aromatic dihydroxy compounds catechol (7), resorcinol (8), 2,3‐dihydroxynaphthalene (9), 1, 8‐dihydroxynaphthalene (10) react with A to form 21 to 24, but mainly by protolytic BCvinyl fission to give the 2,5‐dihydro‐1,2,3‐dioxaboroles (e.g. 7f1, 9f1, 10f1) and the acyclic boron‐free compounds 7f′3, 9f3, 10f3. The MS and NMR (1H, 11B, 13C, 29Si) data of the new compounds are discussed.

Condensation polymerization of 2,2′‐diiodobiphenyl‐4,4′‐dicarbonyl dichloride with some mono‐ and dihydroxy aromatic compounds

AbstractSeveral potentially thermostable polyesters 3a–1 were prepared by Schotten‐Baumann condensation of 2,2′‐diiodo‐4,4′‐biphenyldicarbonyl dichloride (1) with several aromatic hydroxy compounds 2a–1. The reactivity of 1 towards various phenols was tested and the spectra of the resulting model compounds 4a–d were compared with those of the polymers. With some exceptions (3h and 3c) the polyesters were found to be soluble in organic solvents. Their inherent viscosities vary between 0,1 and 0,45 dl · g−1 (in CHCl3 at 25°C). The values of the inherent viscosity were in the range of 0,06–0,45 dl/g (c = 0,2 g/dl in CHCl3 at 25°C). The melting points of the polymers were found to be higher than 300°C.

Stability Constants of Biligand Chelates of Lanthaum(II) and Neodymium(II) with NTA, HEDTA, EDTA, CYDTA and DTPA as Primary Ligands and Aromatic Dihydroxy Compounds as Secondary Ligand

Stability Constants of Biligand Chelates of Lanthaum(II) and Neodymium(II) with NTA, HEDTA, EDTA, CYDTA and DTPA as Primary Ligands and Aromatic Dihydroxy Compounds as Secondary Ligand

Phosphonitrilic chloride. XXV. Synthesis of cyclolinear phosphazene polymers by polycondensation reaction of tetrachlorodiphenylcyclophosphazene trimer and aromatic dihydroxy compounds

AbstractTetrachlorodiphenylcyclophosphazene trimer P3N3Cl4(C6H5)2 (TCP) was synthesized by Friedel‐Crafts reaction. Then, polycondensation reactions of TCP with aromatic dihydroxy compounds were carried out in pyridine as a solvent. The polycondensation products obtained from the reaction of TCP with aromatic dihydroxy compounds were soluble in the most polar solvents. The measured molecular weight was about 1,100 to 3,400. A difference in the molecular weights resulted from a different kind of used aromatic dihydroxy compounds. All polycondensation products were amorphous, white or yellow coloured solids. The polycondensation product obtained from TCP and p,p'‐dihydroxydiphenyl showed the highest softening point at about 260 to 267°C. Consequently, this product seemed to be the most stable against flame. Also it was found that the polycondensation products obtained from TCP and bisphenol‐A or p,p'‐dihydroxydiphenylsulfone had a three dimensional network structure as they had no softening point.

Polyorthocarbonates

AbstractHitherto unreported aromatic polyorthocarbonates have been synthesized by the reaction of dichlorodiphenoxymethane and various aromatic dihydroxy compounds. magnified image The polymers possess the structure of a methanetetra‐ol ether (carbonic acid orthoester) in the main chain. The direct structural evidence was obtained by 13C NMR. High molecular weight, linear polyorthocarbonates were derived from sterically unhindered bisphenols. The polymers were noncrystalline, and clear, flexible films were obtained by casting from solution. Aromatic polyorthocarbonates decomposed above 360°C under nitrogen. The polymers were extremely stable under basic conditions but were unstable in strongly acidic media, particularly at elevated temperatures.

Preparation and properties of condensation polymers containing a phosphorus–nitrogen heterocycle and derivatives of hydroquinone

AbstractCondensation polymers were obtained by the reaction of several aromatic dihydroxy compounds (especially substituted hydroquinones) and 1,3‐dimethyl‐2,4‐dithio‐2,4‐dichloro‐1, 3‐diaza‐2,4‐diphosphetidine. The condensation polymers thus obtained were investigated on their thermal behavior. The thermal stability is lowered in the following series: hydroquinone ≈ resorcinol > tetramethylhydroquinone ≫ tetrachloro‐hydroquinone ≈ tetrafluorohydroquinone ≫ pyrocatechol. The infrared spectra of these new polymers have been measured and are discussed in detail.

165. High coking polymers from interaction of diamino- and dihydroxy-aromatic compounds

165. High coking polymers from interaction of diamino- and dihydroxy-aromatic compounds

Bacterial degradation of aromatic compounds

AbstractThe bacterial degradation of catechol, 3‐methylcatechol, 2,3‐dihydroxy‐β‐phenylpropionic acid, and protocatechuic acid has been studied in detail. From the results obtained a general sequence has been proposed for the microbial oxidation of dihydroxy aromatic compounds.