A study of the chemisorption of a series of aminophenols on plasma-grown aluminium and magnesium oxides by IETS

Inelastic electron tunnelling spectroscopy (IETS) has been applied to study the adsorption of a series of aminophenols on plasma-grown aluminium and magnesium oxides. Vapour-phase doping of these surfaces was used and spectra recorded for 1,2-aminophenol, 1,3-aminophenol and 1,4-aminophenol. The tunnel spectra of the 1,2- and 1,3-aminophenols show that their chemisorption at both oxide surfaces is via reaction between phenolic and surface hydroxyl groups. For the 1,4-aminophenol example, adsorbate chemisorption involves transfer of surface-bound protons from the oxide in amino-group protonation. Some of these protons are replaced by deprotonation of the phenol at surface oxide ions. Observed band intensities for all three systems on aluminium oxide are held to be indicative of an adsorbate orientation on the surface which is close to the vertical. In contrast, those for magnesium oxide are more consistent with a non-vertical configuration.     

Adsorption of some functionalized aliphatic compounds on plasma-grown thin-film aluminium and magnesium oxides

A study of the inelastic electron tunnelling (IET) spectra of N,N-diethyl-1,2-diaminoethane, N,N′-diethyl-1,2-diaminoethane, N,N′-dimethyl-1,2-diaminoethane, N,N,N′,N′-tetraethyl-1,2-diamino-ethane and N,N,N′,N′-tetramethyl-1,2-diaminoethane, shows all five systems to form five-membered chelate structures with both nitrogen atoms present in the adsorbate acting as Lewis donors at the same cation on either aluminium oxide or magnesium oxide. The IET spectra for the N-ethyl-2-aminoethanol, N,N-diethyl-2-aminoethanol and N,N-dimethyl-2-aminoethanol also examined indicate that similar alkoxy-amino chelated structures are formed with these adsorbates. For the aminoethanols adsorption—chelation appears to involve adsorbate deprotonation and hydroxyl depletion of the oxide surfaces involved with concomitant binding of the nitrogen atom present to the surface metal ion involved in alkoxide formation.     

A study by IETS of the chemisorption of benzotriazole and benzimidazole on plasma-grown aluminium and magnesium oxides

The inelastic electron tunnelling spectra of benzotriazole and benzimidazole suggest that these are adsorbed on thin-film plasma-grown magnesium oxide by deprotonation thus forming an anionic surface species. Conversely, the formation of a cationic adsorbate seems likely for both systems on the corresponding less basic aluminium oxide surface.     

Synthesis of banana-like 1,3-dihydroxybenzene and 2,7-dihydroxynaphthalene esters and luminescence of their terbium(III) complexes

New esters of 1,3-dihydroxybenzene and 2,7-dihydroxynaphthalene with 4-(4-alkoxybenzoyloxy)-2-(or 3-)methoxybenzoic acids were synthesized. The correlation between their structure and liquid crystal properties was examined, and the luminescence characteristics of terbium(III) complexes with these esters were studied.     

Determination of Dihydroxybenzenes in Plastic Food Packaging Materials and in Food Simulating Liquids Using Capillary Electrophoresis

A capillary electrophoresis method has been developed to determine 1,2-dihydroxybenzene and 1,3-dihydroxybenzene in the food simulants distilled water, 3% acetic acid, 15% ethanol, and olive oil. Both substances, used as monomers and additives to make food packaging plastics, could be analyzed within 15 min. The 1,4-dihydroxybenzene isomer was unretained and eluted with the electroosmotic flow, and so the CE method can give only a semi-quantitative estimate of this isomer if it is present as a migrant. The analytical recovery for the 1,2- and 1,3-isomers from spiked simulants was good at 87% to 98% except for 1,2-dihydroxybenzene which could only be recovered to the extent of 58% from olive oil. Calibration graphs were linear and the limit of detection for each substance was 0.6 mg/kg, which is well below migration limits for these substances. It is concluded that CE offers a rapid and reliable analysis for the control of migration from plastics intended for food contact which employ 1,2-dihydroxybenzene or 1,3-dihydroxybenzene during manufacture, and offers a screening method for 1,4-dihydroxybenzene migration.     

Reactions of 1,2-diaza-1,3-dienes with thiol derivatives: a versatile construction of nitrogen/sulfur containing heterocycles

The synthesis of substituted 2,3-dihydro-1,4-thiazines, fused cycloalkyl-1,4-thiazines, 1,4-benzothiazines and fused cycloalkyl-1,4-benzothiazines by 1,4-addition of 1,2-aminothiols to 1,2-diaza-1,3-dienes bearing carboxylate, carboxamide, or phosphorylated groups and subsequent internal heterocyclization is described. The reaction of carboxylated 1,2-diaza-1,3-butadienes with 2-(butylamino)ethanethiol affords 1,4-thiazinan-3-ones. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-aminothiols produces 2,3-dihydro-1,4-thiazines and 1,4-benzothiazines.     

Vibrational analysis of substituted phenols: part I. Vibrational spectra,normal coordinate analysis and transferability of force constants of some formyl-, methoxy-, formylmethoxy-, methyl- and halogeno-phenols

The Raman (including FT-Raman) and Fourier transform infrared (FTIR) spectra of 1,3-dihydroxybenzene, 1,4-dihydroxybenzene, 2-hydroxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde, 1,2-dihydroxy-3-methoxybenzene, 2,5-dihydroxytoluene, 2,6-dihydroxytoluene, pentachlorophenol and pentabromophenol were measured. Raman polarisation measurements were made wherever possible. A normal coordinate treatment was carried out for both the in-plane and out-of-plane vibrations of these molecules using a 123-parameter-modified valence force field. An overlay least-squares technique was employed to refine the force constants using 347 frequencies of 10 molecules. The reliability of these force constants was tested by making a zero-order calculation for 10 related molecules. Unambiguous vibrational assignments of all the fundamentals were made using the potential energy distributions and eigenvectors.     

卡尔曼滤波紫外光度法同时测定邻、间、对苯二酚

研究了苯二酚三种同分异构体水溶液的紫外吸收光谱，在ｐＨ３．６的缓冲溶液中，邻、间、对苯二酚的紫外吸收峰分别为２７５ｎｍ、２７３ｎｍ和２８８ｎｍ，三者重叠严重。选取在２４０ｕｍ～２９０ｎｍ范围内，每隔１ｎｍ测量一次吸光值共５１个点，采用卡尔曼滤波进行处理。可以获得较满意的结果。对１０个不同比例组成的标准混合液进行测定，邻、间、对苯二酚三者的平均回收率分别为９７．４％，１０１．７％和９８．０％，标准偏差分别为１．７２％，３．８６％和２．０４％。对模拟试样中加入标准的回收率均在９６．０％～１０３．０％之间。     

卡尔曼滤波紫外光度法同时测定邻、间、对苯二酚

研究了苯二酚三种分异构体水溶液的紫外吸收光谱，在ＰＨ３．６的缓冲溶液中，邻、间、对苯二酚的紫我吸收峰分别为２７５ｎｍ，２７３ｎｍ和２８８ｎｍ三者重叠严重。选取在２４０ｎｍ－２９０ｎｍ范围内，每隔１ｎｍ测量一次吸光值截５１个点，采用卡尔曼滤波进行处理，可以获得较满意的结果，对１０个不同比例组成 标准混合液进行测定，邻、间、对苯二酚三者的平均回收率分别为９７．４％，１０１、７％和９８．０％，标准偏差分     

Effects of structural isomerism on solution behaviour of solutes: Apparent molar volumes and isentropic compression of catechol,resorcinal, and hydroquinone in aqueous solution at T = (283.15, 293.15, 298.15, 303.15, and 313.15) K

Effects of structural isomerism on solution behaviour of dihydroxybenzenes were examined through the determination of volumetric properties such as apparent molar volumes, apparent molar isentropic compressions, and isobaric expansions. The isomers were 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), and 1,4-dihydroxybenzene (hydroquinone). The volumetric properties were determined from accurate density and speed of sound measurements at T = (283.15, 293.15, 298.15, 303.15, and 313.15) K and at various concentrations. Values at infinite dilution of these parameters were obtained by suitable extrapolation procedures. The results are discussed in terms of hydrophobic, hydrogen bonding, and dipole–dipole interactions between the three isomers and water. Catechol was found to have the strongest hydrophilic and the weakest hydrophobic interactions with water among the three isomers.     

Reactivity of hydrogen species on oxide surfaces

Hydrogen species on oxides are widely involved in oxides-catalyzed reactions such as H_2/hydrocarbon oxidation, hydrogenation/dehydrogenation, water-gas shift, and water-splitting reactions. Thus identifications of hydrogen species on oxide surfaces and their reactivity are important for fundamental understanding of these oxides-catalyzed reactions. In this Feature Article, we briefly review our research progress on the reactivity of various hydrogen species on oxides, including surface hydroxyl species,hydride species and hydrated protons. We have successfully developed effective strategies of using gas-phase atomic H to controllably create oxygen vacancies and prepare various hydrogen species on oxide model catalysts under ultra-high vacuum(UHV) conditions and using well-defined oxide nanocrystals with different surface structures and oxygen vacancy concentrations to study the H_2-oxide interaction under ambient or even higher H_2 pressures. Reactivity of various hydrogen species on oxide surfaces has been identified, including local oxygen vacancy-controlled reactivity of OH species, oxygen vacancystabilized hydride species, homolytic dissociation of H2 at oxygen vacancies of reduced oxide surfaces into hydride species accompanied by surface oxidation, photoexcited holes-stimulated desorption of hydride species, electron-stimulated desorption of hydride and OH species, and photoexcited electrons-stimulated desorption of hydrated protons. Strong influences of oxygen vacancies in oxides on both stability and reactivity of various hydrogen species on oxide surfaces are highlighted.     

Thermodynamic Properties of Binary Mixtures of Butanediols with Water

Ultrasonic velocities and densities at five different temperatures over the entire composition range for aqueous solutions of 1,2, 1,3, 1,4, and 2,3 butanediols were measured. Excess volumes and adiabatic compressibilities were calculated using the experimental data. Apparent and partial molar volumes and compressibilities were analyzed to evaluate the departure from ideal solution behavior. From the analysis of the results, the interactions of isomeric butanediols with water are discussed in terms of the placements of hydroxyl groups in the isomeric butanediol molecules.     

Sulfoalkylation of 1,2-Dihydro-3,6-pyridazine- and 2,3-Dihydro-1,4-Phthalazinediones and Their N-Phenyl Derivatives by 1,3-Propanesultone and Bromoalkanesulfonates

When 1,2-dihydropyridazine-3,6-, 2,3-dihydrophthalazine-1,4-, 1-phenyl-1,2-dihydropyridazine-3,6-, and 2-phenyl-2,3-dihydrophthalazine-1,4-diones react with 1,3-propanesultone and bromoalkanesulfonates, depending on the nature of the sulfoalkylating agent in the case of 1,2-dihydropyridazine-3,6- and 2,3-dihydrophthalazine-1,4-diones, either N,O- or O,O1-disulfoalkylated compounds may be formed, while O-monosulfoalkylated reaction products may be formed in the case of the N-phenyl-substituted derivatives of the above-indicated azinediones.     

Synthesis, structure, and reactivity of novel 3,4-diphosphacyclobutenes bearing silyl groups

[reaction: see text] Copper-mediated homocoupling of sterically hindered 2-(2,4,6-tri-tert-butylphenyl)-1-trialkylsilyl-2-phosphaethenyllithiums afforded 1,2-bis(trialkylsilyl)-3,4-diphosphacyclobutenes (1,2-dihydrodiphosphetenes) through a formal electrocyclic [2+2] cyclization in the P=C-C=P skeleton as well as 2-trimethylsilyl-1,4-diphosphabuta-1,3-diene. Reduction of 1,2-bis(trimethylsilyl)-3,4-diphosphacyclobutenes followed by quenching with electrophiles afforded ring-opened products, (E)-1,2-bis(phosphino)-1,2-bis(trimethylsilyl)ethene and (Z)-2,3-bis(trimethylsilyl)-1,4-diphosphabut-1-ene. The structures of the ring-opened products indicated E/Z isomerization around the C=C bond after P-P bond cleavage of 5, and the isomerization of the P-C=C skeleton. Ring opening of 1,2-bis(trimethylsilyl)-3,4-diphosphacyclobutenes affording (E,E)- and (Z,Z)-1,4-diphosphabuta-1,3-dienes was observed upon desilylation.     

Thermal and electron-impact transformations of cis-1,2-dibbnzoylalkenes

Several cis-1,2-dibenzoylalkene derivatives have been prepared in yields ranging between 60–80%, through the Diels-Alder addition of the appropriate dienes to dibenzoylacetylene. These include, 2,3-dibenzoyl-bicyclo [2.2.1]hepta-2,5-diene (10), 2,3-dibenzoylbicyclo[2.2.2]octa-2,5-diene (11), 7-oxa-2,3-dibenzoyl-bicyclo [2.2.1]hepta-2,5-diene (12), 1,4-diphenyl-2,3-dibenzoyl-1,4-epoxynaphthalene (13) and 9,10-dihydro-11,12-dibenzoy1-9, 10-ethenoanthracene (15), formed from cyclopentadiene, cyclohexa-1,3-diene, furan, 1,3-diphenylisobenzofuran and anthracene, respectively.

Thermolysis of 2,3-dibenzoylbicyclo[2.2.1]hepta-2,5-diene gave chiefly cyclopentadiene, arising through a retro-Diels-Alder mode of fragmentation. Similar retro-Diels-Alder fragmentations have been observed in the cases of 7-oxa-2,3-dibenzoylbicyclo[2.2.1]hepta-2,5-diene and 9,10-dihydro-11,12-dibenzoyl-9,10-ethenoanthracene. The thermoylsis of 1,4-diphenyl-2,3-dibenzoyl-1,4-epoxynaphthalene, however, gave a mixture of 1,3-diphenylisobenzofuran and 1,2-dibenzoylbenzene. The formation of 1,2-dibenzoylbenzene in this case has been shown to be through the air-oxidation of 1,3-diphenylisobenzofuran. Thermolysis of 2,3-dibenzoylbicyclo[2.2.2]octa-2,5-diene, on the other hand, gave a nearly quantitative yield of 1,2-dibenzoylbenzene, which did not undergo further transformation even on heating around 260° for several hours. In none of these cases, the expected pericyclic transformation, analogous to the conversion of cis-1,2-dibenzoylstilbene (6) to the isomeric 2,2,3,4-tetraphenylbut-3-enolide (9), has been observed under thermal conditions. Treatment of 9,10-dihydro-11,12-dibenzoyl-9,10-ethenoanthracene (15) with phosphorous pentasulphide resulted in the formation of a mixture of 12,14-diphenyl-9, 10(3', 4')furanoanthracene (28) and 12,14-diphenyl-9,10(3',4')thiophenoanthracene (31), arising through the postulated intermediates, 9,10-dihydro-11-benzoyl-12-thiobenzoyl-9,10-ethenoanthracene (26) and 9,10-dihydro-11,12-dithiobenzoyl-9, 10-ethenoanthracene (29), respectively.

The electron-impact induced transformations of the cis-1,2-dibenzoylalkenes, 6, 10, 11, 12, 13 and 15 on the other hand, can be rationalized in terms of both retro-Diels-Alder type fragmentations and pericyclic transformations of the dibenzoylalkene components.     

Glycosylidene Carbenes. Part 14. Glycosidation of partially protected galactopyranose-, glucopyranose-, and mannopyranose-derived vicinal diols

The relation between H-bonding in diequatorial trans-1,2 and axial, equatorial cis-1,2-diols and the regioselectivity of glycosidation by the diazirine 1 was examined. H-Bonds were assigned on the basis of FT-IR and ¹H-NMR spectra (Fig. 1). Glycosidation by 1 of the gluco-configurated diequatorial trans-2,3-diols 4–7 yielded the mono-glucosylated products 16/17/20/21 (69–89%); 1,2-/1,3-linked products (37–46:63–54), 24/25/28/29 (60–63%; 1,2-/1,3-linked products 46–51:54–49), 32–35 (69–94%; 1,2-/1,3-linked products 45–52:55–48), and 36/37/40/41 (59–63%; 1,2-/1,3-linked products 52–59:48–41), respectively (Scheme 1, Table 3). The disaccharides derived from 4, 5 , and 7 were characterized as their acetates 18/19/22/23, 26/27/30/31 , and 38/39/42/43 , respectively. Glycosidation of the galacto-configurated diequatorial 2,3-diols 8 and 9 and the manno-configurated diequatorial 3,4-diol 10 by 1 (Scheme 2, Table 3) also proceeded in fair yields to give the disaccharides 44–47 (69–80%;1,2-/1,3-linked products ca. 1:1), 48–51 (51–61%;1,2/-1,3-linked products 54–56:56–54), and 56/57/60/61 (71–80%; 1,3-/1,4-linked products 49–54:51–46), respectively. The 1,3-linked disaccharides 56/57 derived from the diol 10 were characterized as the acetates 58/59 . The regio- and stereoselectivities of the glycosidation by 1 were much better for the α-D -manno-configurated axial, equatorial cis-2,3-diol 11 and the galacto-configurated axial, equatorial cis-3,4-diol 13 (1,2-/1,3-linked disaccharides ca. 3:7 for 11 and 1,3-/1,4-linked disaccharides ca. 4:1 for 13 ; Scheme 3, Table 4). The regio- and stereoselectivity for the β-D -manno-configurated cis-2,3-diol 12 were, however, rather poor (1,2-/1,3-linked products 48:52). The 1,2-linked disaccharides 66/67 derived from 12 were characterized as the acetates 70/71 . Koenigs-Knorr-type glycosidation of the cis-diols 11–13 by 2 or 3 proceeded with a similar regio- and a higher stereoselectivity (α-D > β-D with the donor 2 and α-D < β-D with the donor 3 ) than with 1 , with the exception of 12 which did not react with 2 . The regioselectivity of the glycosidations by 1 agrees fully with the H-bonding scheme of the diols and with the hypothesis that the intermediate carbene is preferentially protonated by the most weakly H-bonded OH group. The regioselectivity of the glycosidation by 2 and by 3 is determined by a higher reactivity of the equatorial OH groups and by H-bonding. Several H-bonded and equilibrating isomers of a given diol may intervene in the glycosidation by 1 , or by 2 and 3 , resulting in the same regioselectivity. The low nucleophilicity of 12 and the low degree of regioselectivity in its reaction with 3 show that stereoelectronic effects may also profoundly influence the nucleophilicity of OH groups.     

Reaction of Triphenylphosphine Oxide with ortho-Dihydroxyaromatic Compounds

Triphenylphosphine oxide was first reacted with 2,3-dihydroxynaphthalene, as well as with halo- and alkyl-substituted 1,2-dihydroxybenzenes to obtain the corresponding (ortho-naphthylenedioxy)- or (ortho-phenylenedioxy)triphenylphosphoranes.     

Viscosity, Surface Tension, and Refractive Index Measurements of Mixtures of Isomeric Butanediols with Water

Solution properties of aqueous mixtures of isomeric butanediols have been investigated employing viscosity, surface tension, and index of refraction measurements as functions of temperature. The deviation of viscosity, surface tension, and molar refraction from ideal solution behavior is evaluated from the experimental data. The deviation from ideality is discussed in terms of molecular interactions between the components. Surface activity of the diols is evident from the surface tension measurements. It is found that the degree of hydrophobicity of the diols varies in the order 1,2 > 2,3 > 1,3 > 1,4. The strength of interaction of diols with the water varies in the order 2,3 > 1,4 1,3 > 1,2.     

Synthesis of functionalized α-amino-phosphine oxides and -phosphonates by addition of amines and aminoesters to 4-phosphinyl- and 4-phosphonyl-1,2-diaza-1,3-butadienes

1,2-Diaza-1,3-butadienes derived from phosphine oxides and phosphonates and with optically active substituents on N-1 and C-3 are obtained by 1,4-elimination from chlorohydrazonoalkyl-phosphine oxides and -phosphonates in the presence of bases. Michael addition (1,4-addition) of ammonia, aliphatic and aromatic amines and aminoesters to these azo-alkenes gives functionalized α-amino-phosphine oxides and -phosphonates.     

An IETS study of the chemisorption of 1,2- and 1,4-diaminobenzene on thin-film plasma-grown aluminium oxide

The inelastic electron tunnelling spectra of 1,2- and 1,4-diaminobenzene on thin-film plasma-grown aluminium oxide suggests that these molecules are adsorbed on this surface via Lewis acid—Lewis base and hydrogen-bonded interactions, with chelate formation at the surface likely in the case of the 1,2-diamino compound. Protonation of nitrogen in both structures is also considered given the spectral features observed. In both adsorbates the ring plane is believed to be near perpendicular with respect to the local oxide surface.