P.C. Wailes

Insertion reactions of dicyclopentadienyldimethylzirconium and related cyclopentadienyl compounds with sulphur dioxide and nitric oxide

Abstract The reactions of (π-C 5 H 5 ) 2 Zr(CH 3 ) 2 are characterized by lability of the methyl groups, one or both of which may be displaced by reaction with hydrogen, phenylacetylene, methanol or lead chloride. Sulphur dioxide will insert between both methyl groups and the zirconium atom and also between one of the cyclopentadienyl ligands and the metal atom. Nitric oxide will insert between one of the methyls and the zirconium leading to a novel zirconium complex of methylnitrosohydroxylamine. Insertion reactions of SO 2 and NO were also observed with the monomethyl derivative (π-C 5 H 5 ) 2 Zr(Cl)CH 3 , and with (C 5 H 5 ) 4 Zr.

Hydrido complexes of zirconium: III. Reactions with acetylenes to give alkenylzirconium derivatives

Abstract The zirconium hydride (C5H5)2Zr(H)Cl reacts with both mono and disubstituted acetylenes by addition of Zr-H across the triple bond. Generallytrans-alkenyl derivatives result although in some cases mixtures of isomers are formed. With monosubstituted acetylenes (C5H5)2ZrH2 behaves similarly giving di(trans-alkenyl)zirconium compounds, but with diarylacetylenes hydrogen is evolved and tetraarylbutadiene complexes result.

Dimeric dicyclopentadienyltitanium(III) halides

Abstract The synthesis and characterization of dicyclopentadienyltitanium(III) fluoride completes the series (Cp 2 Ti III X) 2 [where Cp = π-cyclopentadienyl; X = F, Cl, Br or I]. Two new methods of preparation are reported for the other members of the series. Structuralinvestigation by means of molecular weight determinations, spectroscopic, and magnetic susceptibility measurements confirm the dimeric model shown below.

Sulphur dioxide insertion reactions with dicyclopentandienyltitanium and -zirconium alkyl and aryl compounds

Abstract Sulphur dioxide was found to react in the expected manner with alkyl- and aryldicyclopentadienyltitanium compounds to yield the red monomeric O-sulphinates (π-C5H5)2Ti(O2SCH3)2, (π-C5H5)2Ti(O2SCH3Cl, and (π-C5H5)2Ti(O2SC6H5)2. With dicyclopentadienylzirconium compounds, the sulphur dioxide inserts into the zirconium-alkyl bond also into the zirconium-cyclopentadienyl bond in certain cases, even though the cyclopentadienyl group is π-bonded to zirconium. The preparations of the O-sulphinates [π-C5H5(C5H5SO2)Zr(O2SCH3)Cl]n, [π-C5H5(C5H5SO2) ZrO]n and [π-C5H5(C5H5SO2)ZrSO3]n are reported.

Five-coordinate organotitanium(IV) dithiocarbamates

Monocyclopentadienyltitanium(III) halides, CpTiX2 (X = Cl or Br) are oxidized by thiuram disulphides, R2NC(S)Sue5f8SC(S)NR2 [R = CH3, C2H5, n-C4H0 or R2 = —(CH2)5—] to monomeric dithiocarbamates, CpTi(S2CNR2)X2, which contain five-coordinate titanium.

Novel reactions of monocyclopentadienyltitanium(III) dihalides with organic carbonyl groups

Abstract Cyclopentadienyltitanium(III) dihalides, CpTiX2 (where X = Cl or Br), or their tetrahydrofuranates, CpTiX2·THF, have been brought into reaction with organic compounds containing the carbonyl group (benzophenone, acetophenone, acetone, and benzaldehyde). The physical and chemical properties of the yellow crystalline products suggest that organotitanium(IV) derivatives are formed by an intramolecular “redox” process. Evidence for reversibility of the reaction is offered in the case of benzophenone complexes.

Continuous hydrogenation of Yallourn brown-coal tar

Abstract Hydrogenation of brown-coal tar offers a source of liquid fuel or chemical feedstock. In order to make a preliminary assessment of its potential, tar from pyrolysis of Yallourn brown-coal briquettes has been hydrogenated in a laboratory scale continuous-flow hydrogenation unit over sulphided nickel molybdate and cobalt molybdate catalysts. Over a 148 h running period the product oil was characterized by periodical measurement of refractive index, infrared spectrum, density, viscosity, elemental analyses and boiling range. Effluent gases were also monitored. The fifty most abundant compounds in the product were identified by gas chromatography/mass spectrometry. The oils contain 50–60% aromatics and boil over a wide range, including gasoline to gas oil fractions. Carbon and iron deposition on the catalyst caused a decrease in surface area and a consequent deterioration in product quality. The use of an efficient pre-coking furnace should increase catalyst life significantly.

Upgrading of coal-derived products☆

Abstract A number of processes such as pyrolysis, solvent extraction, etc. can be used for the primary upgrading of coal to liquid products. The type of process used can have a significant influence on the character of the product obtained. The chemistry and associated problems involved in the catalytic hydrotreatment of flash pyrolysis tars are discussed in this Paper. The difficulties encountered in the upgrading of flash pyrolysis tar are due principally to factors such as the thermal instability of the tar (high Conradson carbon), particulate matter in the tar and the high molecular weight of the tar. The design and mode of operation of the reactor have been chosen to minimize such problems. An important function of the catalyst used in this work (Co-Mo-Al 2 O 3 and Ni-Mo-Al 2 O 3 ) was to reduce the heteroatom content of the feedstock. A description of the type of molecules and reactions involved in tar upgrading is given.

Constitution of tars from flash pyrolysis of Australian coals: 3. A structural study of Millmerran asphaltene components by hydrogenolysis

Asphaltenes derived from tar from the flash pyrolysis of Millmerran coal have been separated into acid, base, polyfunctional and neutral fractions by ion-exchange chromatography. Each fraction was studied by high-pressure catalytic hydrogenolysis followed by g.c.-m.s. analysis of the volatile products. The high content of n-alkanes from C9 to C32 in the organic products highlights the unusual maceral composition of Millmerran coal and its high HC ratio. The results show that most of the asphaltenes are made up of small 1 — or 2-ring aromatic units probably linked by methylene chains bonded through intermediate functional groups. In some cases, the asphaltene structures appear to be ‘simpler’ than the corresponding coal-tar resin structures in the maltenes. Because no amphoteric molecules were detected these results support the concept of an acid-base structure for coal-derived asphaltenes.

Constitution of tars from the flash pyrolysis of Australian coals: 2. Structural study of Millmerran coal-tar resins by hydrogenolysis

Abstract The structures of the acid, base, polyfunctional and neutral resin fractions of Millmerran coal tar have been studied by high-pressure catalytic hydrogenolysis followed by g.c.-m.s. analysis of the volatile products. n -Alkanes from C 9 to C 32 constitute 4–24% of the organic products. Each fraction shows a characteristic n -alkane distribution. The alkanes are considered to be an integral part of the coal-tar resin structure. The results show that 40–70% of the coal-tar resin fractions consist of 1- or 2-ring aromatic units substituted or linked by long methylene chains.