The use of HPLC for the analytical determination of diisocyanates and acid anhydrides in the air of working environments

Abstract

Measurements of airborne concentrations of (monomeric) 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6- TDI), 4,4′ - diisocyanato diphenylmethane (MDI) and phthalic anhydride have been performed at 17 Danish manufactories using these compounds in the production of polyurethane foams, insulating materials, elastomers, coatings, lacquers and glues.

Diisocyanate vapours at workplaces were collected in impingers, containing a solution of 9-(N-methylaminomethyl)-anthracene (1 × 10^?4 M) in toluene. By reaction with this amine compound the diisocyanates are converted to stable urea derivatives. Phthalic anhydride particles were collected on glass fiber filters.

For separation and detection of the diisocyanate derivatives and the phthalic acid formed upon hydrolysis of its anhydride, reversed phase high performance liquid chromatography on a bonded octadecylsilyl phase using isocratic elution with acetonitrile/water and UV-monitoring at Λ = 254 nm were used. The results obtained for each manufactory are presented.     

Novel oxazepinedione-derived symmetric dimers: synthesis and mesophase characterisation of seven-membered heterocyclic compounds

The synthesis and characterisation of three sets of symmetric dimeric compounds composed of seven-membered oxazepinedione heterocyclic rings were carried out. All the dimers possess the tetradecyl- (n = 14) alkyl side chain attached to the nitrogen atom of the oxazepinedione core. The oxazepinedione core in turn was connected with varied connecting spacers (n = 4, 6, 8, 10 and 12). The dimers were spectroscopically characterised by FT-IR, ¹H-NMR, ¹³C-NMR and elemental analysis techniques. The compounds were investigated for liquid crystalline properties using differential scanning calorimetry and polarising optical microscopy with heating assembly. The precursor imines 2a–e itself started exhibiting liquid crystalline SmA/tilted hexatic mesophase. Further fusion of 2a–e with maleic anhydride, succinic anhydride and phthalic anhydride gave the novel oxazepinedione-derived symmetric dimers 3a–e, 4a–e and 5a–e respectively. The dimers 3a–e and 4a–e did not exhibit any liquid crystal (LC) properties. However, the phthalic anhydride-fused oxazepinediones 5a–e show monotropic nematic liquid crystalline phase. The results indicate that the formation of mesophase is dependent on the type of fused oxazepinedione ring.     

Quantitation of 1,2 and 1,4-naphthoquinone in phthalic anhydride by HPLC

Summary A simple method of analysis of the 1,2 and 1,4 isomers of naphthoquinone in crude phthalic anhydride has been developed. The sample was first dissolved in water at 60°C to quantitatively hydrolyse the anhydride to phthalic acid.Analysis of the aqueous solution by reversed-phase HPLC using 7525 methanol:water mobile phase resulted in excellent resolution between the phthalic acid and the naphthoquinones and enabled quantitative measurement of each of the naphthoquinones to 0.1 % in crude phthalic anhydride.     

Zur Reaktion von 1,3-Oxazolidinen mit Dicarbonsäureanhydriden

Reaction of 3-methyl-1,3-oxazolidine with phthalic anhydride in chloroform leads to ring opening and higher oligomers2 are formed. These are cleaved by addition of protic solvents and 2-methylaminoethyl hydrogenphthalate3 a is obtained. Other 1,3-oxazolidines and succinic anhydride behave similarly.

Herrn Prof. Dr. Dr. h. c.Karl Kratzl mit den besten Wünschen zum 70. Geburtstag gewidmet.     

Synthesis and antitumor activity evaluation of some 1, 2, 4-triazine and fused triazine derivatives

Reactions of 3-hyrazino-5,6-diphenyl-1,2,4-triazine with various carbonyl compounds such as ethyl acetoacetate, acetylacetone, benzoin, isatin, phthalic anhydride, phenyl isocyanate and acetic anhydride were discussed. Its reactions with α, β unsaturated compounds such as arylidinemalononitrile, diethyl acetylenedicarboxylate, dibenzylidine hydrazine were studied. These reactions led to the formation of various triazine and fused-triazine derivatives. The antitumor activity of the synthesized compounds was tested against HePG2 and MCF-7 cell lines. Some of the tested compounds were most active, whereas other compounds exhibited little or no activity.     

Mechanism of phthalic anhydride formation in the oxidation of n-pentane on a vanadium-phosphorus oxide catalyst

The reaction paths of product formation in the partial oxidation of n-pentane on vanadium-phosphorus oxide (VPO) and VPO-Bi catalysts are considered. The condensed products of n-pentane oxidation were analyzed by chromatography-mass spectrometry, and the presence of C₄ rather than C₅ unsaturated hydrocarbons was detected. It was found that the concentration of phthalic anhydride in the products increased upon the addition of C₄ olefins and butadiene to the n-pentane-air reaction mixture. With the use of a system with two in-series reactors, it was found that the addition of butadiene to a flow of n-butane oxidation products (maleic anhydride, CO, and CO₂) resulted in the formation of phthalic anhydride. The oxidation of 1-butanol was studied, and butene and butadiene were found to be the primary products of reaction; at a higher temperature, maleic anhydride and then phthalic anhydride were formed. The experimental results supported the reaction scheme according to which the activation of n-pentane occurred with the elimination of a methyl group and the formation of C₄ unsaturated hydrocarbons. The oxidation of these latter led to the formation of maleic anhydride. The Diels-Alder reaction between maleic anhydride and C₄ unsaturated hydrocarbons is the main path of phthalic anhydride formation.     

ORGANOPHOSPHORUS COMPOUNDS,XXX

Abstract

Fluoroenylidenetriphenylphosphorane (1a) reacts with maleic and phthalic anhydrides to give lactones 2a and 3, respectively. The same reagent (1a) extrudes sulphur from thiophthalic anhydride yielding the spiro-1,3-indandione derivative 4. The infrared and mass spectra of the new products are discussed.     

Electron-impact studies XCII–Negative ion-molecule reactions in anhydride systems. Perfluoroacetic anhydride with succinic,maleic and phthalic anhydrides. An ion cyclotron resonance study

The trifluoroacetate anion undergoes reaction with succinic, maleic and phthalic anhydrides to yield 1 : 1 adducts. The molecular anions of maleic and phthalic anhydride also undergo reaction with perfluoroacetic anhydride to produce [CF₃CO₂]^?· Maleic anhydride parent ions produce [M + CF₃CO·]^? ions when allowed to react with perfluoroacetic anhydride.     

Selective vapor‐phase oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H3PW12O40@TiO2 using molecular oxygen as a green oxidant

The oxidation of o‐xylene to phthalic anhydride over Co‐Mn/H₃PW₁₂O₄₀@TiO₂ was investigated. The experimental results demonstrated that the prepared catalyst effectively catalyzed the oxidation of o‐xylene to phthalic anhydride. Also, the synergistic effect between three metals plays vital roles in this reaction. From a green chemistry point of view, this method is environmentally friendly due to carrying out the oxidation in a fixed‐bed reactor under solvent‐free condition and using molecular oxygen as a green and cheap oxidizing agent. The resulting solid catalysts were characterized by FT‐IR, XRD, XPS, ICP‐OES, FESEM, TEM, EDX, DR‐UV spectroscopy, BET and thermogravimetric analysis. The oxidation of o‐xylene yields four products: o‐tolualdehyde, phthaldialdehyde, phthalide and finally phthalic anhydride as the main product. The reaction conditions for oxidation of o‐xylene were optimized by varying the temperature, weight hourly space velocity and oxygen flow rate (contact time). The optimum weight percentage of phosphotungstic acid (HPW) and Co/Mn for phthalic anhydride production were 15 wt % and 2 wt%, respectively. The best Co/Mn ratio was found to be 10/1. Oxygen flow rate was very important on the phthalic anhydride formation. The optimum conditions for oxidation of o‐xylene were T = 370 °C, WHSV = 0.5 h^?1 and oxygen flow rate = 10 mL min^?1. Under optimized conditions, a maximum of 88.2% conversion and 75.5% selectivity to phthalic anhydride was achieved with the fresh catalyst. Moreover, reusability of the catalyst was studied and catalytic activity remained unchanged after at least five cycles.     

An example of quality control of fine chemical intermediates: related impurity analysis of industrial phthalic anhydride by reversed-phase high-performance liquid chromatography

A reliable reversed-phase high-performance liquid chromatographic method has been developed for analysis of related impurities in industrial phthalic anhydride (PA). Maleic acid (hydrolysis product of maleic anhydride), phthalimide, and benzoic acid were separated from phthalic acid (Pa, hydrolysis product of PA) on a C₁₈ column by gradient elution with acetonitrile and 0.1% (v/v) aqueous perchloric acid solution. This method is simple, sensitive, and accurate, and has been successfully applied to quality control of PA for industrial use.     

Solubility and dissolution thermodynamics of phthalic anhydride in organic solvents at 283–313 K

The solubility of phthalic anhydride was measured at 283–313 K under atmospheric pressure in ethyl acetate, n-propyl acetate, methyl acetate, acetone, 1,4-dioxane, n-hexane, n-butyl acetate, cyclohexane, and dichloromethane. The solubility of phthalic anhydride in all solvents increased with the increasing temperature. The Van’t Hoff equation, modified Apelblat equation, λh equation, and Wilson model were used to correlate the experimental solubility data. The standard dissolution enthalpy, the standard entropy, and the standard Gibbs energy were evaluated based on the Van’t Hoff analysis. The experimental data and model parameters would be useful for optimizing of the separation processes involving phthalic anhydride.     

Synthesis and biological assessment of novel cyanopyridine derivatives

New pyridine derivatives bearing p-dimethyl amino phenyl and p-bromophenyl moieties at position-4 and 6 have been prepared. The behavior of pyridone derivative 2 toward ethyl chloroacetate followed by hydrazine hydrate gave pyridinyl acetohydrazide derivative 7, and its behavior toward carbon electrophiles has been investigated by its reaction with aromatic aldehydes, ethyl acetoacetate, acetyl acetone, cyclohexanone, phthalic anhydride, maleic anhydride, and isatin affording the pyridine derivatives 8a–e to 16, respectively. Treatment of compound 2 with acrylonitrile in Et₃N, yielded the N- alkylated derivative 17. Some pyrazole derivatives have been synthesized by interaction of the chalcone 1 with hydrazine hydrate afforded pyrazole derivative 18. Treatment of compound 18 with benzoyl chloride and or acetic anhydride resulted in the formation of the acylated compounds 19 and 20. Elemental and spectroscopic pieces of evidence characterized all the newly synthesized compounds. Some of the synthesized compounds were tested for their antibacterial activities against Gram-positive and Gram-negative bacteria.     

Features of reactions of phthalic anhydride with polyfluorinated alcohols

Polyifluoroalkyl mono- and diesters of phthalic acid were obtained by the reaction of phthalic anhydride with polyfluorinated alcohols. The structure of the polyfluoroalkyl phthalates was studied using IR and ¹H, ¹³C NMR spectroscopy. The nature of the associative interactions between cyclohexanone and polyfluorinated alcohols was revealed.     

The Effect of Glyceride Composition on the Mechanical Properties of Alkyd Resin Films

Abstract

The dynamic mechanical properties of dried films prepared from alkyd resins made by the reaction of phthalic anhydride with synthetic mixtures of the mono-, di-, and trilinoleates of glycerol of the same overall composition are reported. The properties of the films dried at room temperature correlate with the microgel content of the resins, which is a function of the monoglyceride content of the original reaction mixture. Films dried at 120°C show smaller differences in mechanical properties.     

13C?C13 coupling constants in dimethyl phthalate and phthalic anhydride. Determination of signs—III

Relative signs of ¹³C? ¹³C coupling constants between ring carbons and carbonyl carbons in dimethyl phthalate and phthalic anhydride, ¹³C-labelled in both carbonyl groups, have been determined. The two-and three-bond coupling constants are shown to be positive, whereas four-bond coupling constants are negative. Substituent effects on carbon-carbon couplings due to a carboxyl group have been determined and effects of 5-membered ring formation in phthalic anhydride have been observed.     

Thermally stable polymers based on bismaleimides containing amide,imide, and ester linkages

Seven new structurally different bismaleimides were synthesized and characterized by infrared and proton nuclear magnetic resonance spectroscopy. The chain of these polymer precursors was extended by incorporating amidized, imidized, and esterified 4-chloroformyl phthalic anhydride. The bismaleimides containing amide and imide linkages were prepared by a simple synthetic route based on the reaction of the monomaleamic acid derived from various aromatic diamines (1 mol) with 4-chloroformyl phthalic anhydride (0.5 mol) and subsequent cyclodehydration of the intermediate triamic acid. In addition, chain extended bismaleimides were prepared by reacting the monomaleamic acid derived from p-phenylenediamine with several dianhydrides such as p-phenylene bis(trimellitamide anhydride), p-phenylene bis(trimellitate anhydride), and bis-phenol A bis(trimellitate anhydride). The differential thermal analysis scans of bismaleimides showed exotherms at 221–304°C associated with their polymerization reactions. The thermogravimetric analysis traces of polymers did not show a weight loss up to 351–393 and 344–372°C in N₂ and air atmospheres, respectively. The anaerobic char yield of polymers at 800°C was 44–61%. These polymers can be used for fabrication of composites having improved properties.     

Synthesis and radical polymerization of end-methacrylated poly(succinimide) leading to poly(aspartic acid) hydrogel

The polycondensation of aspartic acid in the presence of phthalic anhydride was carried out in mesitylene/sulfolane using o-phosphoric acid as a catalyst. The polymer yields were 91–78%, when 5–20 mol-% phthalic anhydride was added into the feed. The obtained poly(succinimide) carried a phthalic imide unit and a succinic acid unit as end groups. In the MALDI-TOF mass spectrum, the peak-to-peak distances between adjacent signals were 97.07 m/z, corresponding to the calculated value (97.07) of the succinimide unit. Poly(succinimide) was reacted with 2-(methacryloxy)ethyl isocyanate to give end-methacrylated poly-(succinimide), in which the end-functionality of the methacrylate group was ca. 1. End-methacrylated poly-(succinimide) was polymerized with ethylene glycol dimethacrylate using 2,2′-azoisobutyronitrile to give poly(succinimide) gel, which could be converted into water-absorbing poly(aspartic acid) hydrogel.     

Ultrasound-promoted Friedel-Crafts acylation of arenes and cyclic anhydrides catalyzed by ionic liquid of [bmim]Br/AlCl3

A simple and efficient method of Friedel-Crafts acylation of arenes with succinic anhydride, phthalic anhydride and glutaric anhydride under the action of 1-butyl-3-ethylimidazolium ([bmim]Br/AlCl₃ ([bmim]⁺) cation (ionic liquid) and ultrasound irradiation is presented. Thy purity of products was tested by GC-MS and their structures evaluated by IR and ¹H NMR spectroscopy.     

Methylthiofurane: Herstellung und Reaktionen

Preparation and Reactions of Methylthiofurans By lithiation of 3,4-dimethoxyfuran, 2-methylfuran and furan, followed by reaction with dimethyldisulfide, the methylthiofurans 2, 8 , and 10 have been prepared. Reaction of 8 with maleic anhydride has yielded 6-methyl-3-(methylthio)phthalic anhydride ( 9 ), a yellow substance with a strong greenish fluorescence, obviously formed by elimination of H₂O from an unstable cycloadduct. An analgous reaction of 2 resulted in an unexpected mixture from which the following yellow compounds were isolated: 3-hydroxy-4,5-dimethoxy-6-(methylthio)phthalic anhydride ( 3 ), 4-hydroxy-5-methoxy-3,6-bis(methylthio)phthalic anhydride ( 4 ), and bis(S-methyl) (2Z,4E,6Z)-2,3,6,7-tetramethoxy-4,5-bis(methylthio)-2,4,6-octatrienethioate ( 5 ). Compound 5 is also formed on standing of 2 at RT. Mild acid hydrolysis of 2 results in ring-opening accompanied by an intramolecular oxido-reduction to yield S-methyl(3Z)-3-methoxy-4-(methylthio)-2-oxo-3-butenethioate ( 6a ). The structures of compounds 5 and 6a have been determined by X-ray analysis.     

A novel one-pot isocyanide-based four-component reaction: synthesis of highly functionalized 1H-pyrazolo[1,2-b]phthalazine-1,2-dicarboxylates and 1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates

A new protocol has been developed for the efficient synthesis of structurally diverse 1H-pyrazolo[1,2-b]phthalazine-1,2-dicarboxylates and 1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates via a four-component reaction of hydrazine hydrate, dialkyl acetylenedicarboxylates, isocyanides and various cyclic anhydrides such as succinic anhydride, maleic anhydride and phthalic anhydride in ethanol/acetone (1:1) at room temperature in good to moderate yields.