A novel vapor phase process for aromatic ketone synthesis

The vapor phase catalytic reaction between aromatic carboxylic acid and acetic acid was investigated. Many metal oxides catalyzed the reaction between 2methylbenzoic acid (OTA) and acetic acid (AA) to produce 2methylacetophenone (OMA), and weakly acidic oxides such as Th, U, Ce, and La oxide exhibited higher yield of OMA. The OMA yield depended on the catalyst support. SiO₂, Al₂O₃, TiO₂, and ZrO₂ with a surface area of less than 200 m² g^–1 appeared to be suitable as industrial catalyst supports. CeO₂ on Al₂O₃was chosen as an industrial catalyst for the synthesis of OMA because of higher productivity, longer catalyst life, and lifting of legal restrictions on catalyst handling. This catalyst system can also be applied to the syntheses of acetophenone, nitroacetophenone, and chloroacetophenone.     

Multi-turn time-of-flight mass spectrometers with electrostatic sectors

The mass resolution of a time-of-flight (TOF) mass spectrometer is directly proportional to its total flight pathlength. Multi-turn or multi-passage ion optical geometries are necessary to obtain fight distances of sufficient length within reasonable size limitations. We have investigated ion optics for a multi-turn TOF mass spectrometer with electrostatic sectors. The concept of 'perfect' focusing conditions is introduced. Furthermore, a new type of multi-turn TOF mass spectrometer, the MULTUM Linear plus, was developed. It consists of four cylindrical electric sectors and 28 electric quadrupole lenses. It has a vacuum chamber 60 x 70 x 20 cm in size. Mass resolution is demonstrated to increase according to the number of ion cycles. A mass resolution of 350 000 (m/z = 28, FWHM) was achieved after 501.5 cycles. The MULTUM Linear plus analyzer is not simple, however; 28 electric quadrupole lenses are used. In order to reduce the number of ion optical parts, an improved multi-turn TOF mass spectrometer, the MULTUM II, consisting of only four toroidal electric sectors, was also developed. The possibility of tandem mass spectrometric applications using multi-turn TOF mass spectrometers is also discussed.     

Improved spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol in the presence of benzyldimethylstearyltrimethylammonium chloride

An improved spectrophotometric determination of uranium(VI) is proposed using 4-(2-pyridylazo)resorcinol(PAR) in the presence of benzyldimethylstearyltrimethylammonium chloride(BSTAC) as a cationic surfactant. The calibration graph is linear in the range of 0.3-60 microg/10 ml uranium(VI), measuring the absorbance at 550 nm. The reproducibility for 19.0 microg/10 ml uranium(VI) is 0.57%. The third-derivative method using the third-derivative distance (d(3)A/dlambda(3)) among lambda(1) 530 nm, lambda(3) 594 nm and lambda(2) 565 nm was also investigated.     

Highly sensitive spectrophotometric determination of osmium(VIII) with pyrogallolphthalein and hydrogen peroxide in the presence of Brij 35

Summary A highly sensitive determination of osmium(VIII) is based on the decolouring reaction with pyrogallolphthalein (gallein) and hydrogen peroxide in the presence of Brij 35. Beer's law was obeyed in the range of 0–0.5 ng of osmium(VIII) per 10 ml and the apparent decomposed absorption coefficient was 2.5×10⁹ l mol^–1 cm^–1 at 535 nm.Application of xanthene derivatives in analytical chemistry. Part XCIII. Part XCII see ref. [1]     

Synthesis of Potential Antimicrobial Agents from Maltose. III. Introduction of an Amino Group Into the 3′-Position of 1,6-Anhydro-Disaccharides

Abstract

Regioselective cleavage of 1,6-anhydro-maltose (1) with periodate and the subsequent recyclization with nitromethane gave 1,6-anhydro-3′-deoxy-3′-nitro-disaccharides (3). Three diastereomers, prepared by benzylidenation of 3, were separated by column chromatography. Each of 4′,6′-O-benzylidene derivatives successively underwent debenzylidenation, reduction of the nitro group, and peracetylation to give 3′-acetamido-3′-deoxy-disaccharide derivatives (7, 8, and 9). The configurations of the 3-amino sugar moietres in 7 (D-gluco), 8 (D-manno) and 9 (D-galacto) were determined on the basis of the ¹H NMR data. The main product (7) was further modified to the 6-deoxy-6-nitro derivative.     

The biosynthesis of fulvic acid,a fungal metabolite of heptaketide origin

Analyses of the regiochemistry of [¹³C]acetate incorporation into fulvic acid ($\text{2}$) by Penicillium brefeldianum indicates that the metabolite is biosynthesized via a heptaketide intermediate assembled as a single chain of seven C₂, units rather than from two smaller polyketide chains. This information favours a route leading through common C₁₄ intermediates to the three fungal metabolites, citromycetin, fulvic acid and fusarubin.     

Experimental and theoretical study on gas-phase ion/molecule reactions of silver trimer cation, Ag3+, with 12-crown-4

The reaction mechanisms of silver trimer cation, Ag3+, with 12-crown-4 (12C4) were studied experimentally and theoretically. Using a cylindrical ion trap time-of-flight mass spectrometer, gas-phase ion/molecule reactions of Ag3+ with 12C4 were observed. Metal-ligand complexes of [Ag(12C4)]+, [Ag3(12C4)]+ and [Ag3(12C4)2]+, and of [Ag(12C4)2]+ and [Ag3(12C4)3]+, were observed as the reaction intermediates and terminal products, respectively. The formations of the [Ag12C4]+ and [Ag(12C4)2]+ complexes indicated that the neutral dimer (Ag2) had been eliminated from the trimer cation. From the results of ab initio calculations at the HF/LanL2DZ level of theory and the experiments, it is suggested that three 12C4 molecules can attach to Ag3+ through consecutive reactions and that neutral Ag2 can be easily eliminated from [Ag3(12C4)]+.     

Total synthesis of amauromine

Total synthesis of amauromine ($\text{1}$), a novel alkaloid possessing two reversed prenyl groups in its molecule, was described.     

Spectrofluorometric determination of thallium(III) with pyrogallol red and 3,4,5,6-tetrachlorofluorescein

Summary A spectrofluorophotometric determination of thallium(III) is proposed. It is based on the enhancement of the fluorescence reaction of 3,4,5,6-tetrachlorofluorescein (TCF) with Pyrogallol Red (PR) by thallium(III) in the presence of Swanol (AM 301, lauryldimethyl aminoacetic acid betain) as an amphoteric surfactant. The method was found to be suitable for the determination of thallium(III) down to 4.0 g in 10.0 ml by measuring the difference in the relative fluorescence intensities of a TCF/PR/thallium(III) solution and a TCF/PR solution. The recovery test in artificial urine was satisfactory (96±2%).     

Alternative spectrophotometric determination of niobium and tantalum with o-hydroxyhydroquinonephthalein in cationic surfactant micellar media

Summary The alternative and simultaneous spectrophotometric determination of niobium and tantalum was examined by using the colour development between o-hydroxyhydroquinonephthalein (Qnph) and niobium or tantalum in the presence of hexadecyltrimethylammonium chloride (HTAC) in strong acidic media. Beer's law was obeyed up to 10.0 g of niobium and up to 18.0 g of tantalum in a final volume of 10.0 ml. The apparent molar absorption coefficients for niobium and tantalum were 2.18×10⁵ and 2.09×10⁵ l mol^–1 cm^–1 with Sandell's sensitivities of 0.00042 g/cm² niobium at 520 nm and 0.00085 g/cm² tantalum at 510 nm, respectively. The alternative assay of niobium and tantalum was possible by using two methods: Method A — masking method with oxalic acid, Method B — acid adjusting-method using 50% sulfuric acid. These methods were 2–6-times more sensitive than other methods.Application of xanthene derivatives in analytical chemistry. Part XC. Part LXXXIX see ref [1]