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Two series of closely related SNS pincer ligands (L) were synthesised with the major structural variation on the nitrogen backbone containing either the methyl [L = (RSCH2CH2)2NMe: where R = Me (1), Et (2), Bu (3)] or the phenyl [L = (RSCH2CH2)2NPh: where R = Me (4), Et (5), Cy (6)] functional group. When ligands 1–3 were complexed to Ni by reaction with Ni(DME)Cl2 (DME = dimethoxyethane), they respectively yielded three new cationic dimeric [LNi(μ-Cl)3NiL]+ complexes (7–9), whilst ligands 4–6 on reaction with Ni(PPh3)2Br2 respectively yielded neutral mononuclear (LNiBr2) complexes 10–12. All the new compounds were characterised by IR, HRMS, elemental analysis and in addition, single crystal X-ray diffraction for complexes 9–12. X-ray structural data of 9 revealed an unusual three chlorido-bridged Ni dimer with the SNS ligand coordinated in a facial binding mode to the two pseudo-octahedral Ni centres. Molecular structures of complexes 10, 11 and 12 each displayed five-coordinate distorted trigonal bipyramidal geometry around the nickel(II) metal centres. When utilised as catalysts in the tert-butyl hydroperoxide oxidation of n-octane, all the complexes showed activity to mainly products of internal carbon activation (octanones and secondary octanols) with 11 as the most active (10% total substrate to oxygenates yield), whereas 10 was the least active, but most selective towards alcohols (alcohol/ketone = 2.13).

New Cu(II) complexes containing a set of tridentate hybrid SNS ligands were synthesised and fully characterised by IR, HRMS, elemental analysis and single-crystal X-ray diffraction. The complexes with the general formula Cu[bis(Rthioethyl)phenylamine]Cl2 (1); [R = methyl (a); ethyl (b); butyl (c); cyclohexyl (d) and t-butyl (e)] exhibited five-coordinate trigonal bipyramidal geometry around each Cu(II) centre in the solid-state with the S-donor atoms occupying the axial positions. However, complex 1b crystallised as a dimer bridged through a cuprate anion denoted as [1b(μ-CuCl4)1b]. Their application as catalysts in the oxidation of n-octane with hydrogen peroxide (H2O2) as an oxidant gave high substrate conversions to C-8 oxygenate products, mainly octanols, after reduction with PPh3. Notably, complex 1d produced the highest yield of 57% in 1 h reaction time at a catalyst concentration of 1 mol%. In general, high turnover numbers (2830–3180) were recorded for the 1/H2O2 catalytic systems with substantially high combined selectivity of 22–27% to 1-octanol and octanoic acid, which are the more desired products of n-octane oxidation resulting from its terminal carbon (C(1)) activation. The high activity of the catalysts is attributed to metal–ligand cooperative catalysis involving CuII-OOH intermediates as the active species modulated by the tridentate SNS ligands. In comparison with related complexes bearing N-donor atoms, the excellent catalytic performance of these series of CuSNS complexes highlights the critical role of the phenylamine N-donor atom.

WOS: 000443172200016, In this study: Ba, Mn and Pb metal soaps were synthesized using stearic acid with the salts of these metals, and then melting points were determined. Different concentrations of synthesized metal soaps were also used as catalysts for paraffin oxidation. The amount of aldehyde, ketone and carboxylic acids formed as a result of oxidation was determined as an acid value (A.V.) using the titration method. These values were converted to% stearic acid value (%SAD). The result also examines the relationship between Ba, Mn and Pb stearate soaps, behavior on paraffin oxidation as a catalyst and melting points.

This study seeks to address the need for the development of highly active paraffin activation catalysts that are reusable and based on cheap earth abundant metals. Hence, a series of related halide-free 1,3,4-trisubstituted-1,2,3-triazolium ionic liquids (IL)(3a–3f) bearing a variety of substituents were synthesized and fully characterized by spectroscopic and analytical techniques. Crystal structure of the halide derivative, compound 2f is also reported. With the IL as solvents for the dissolution of FeCl2, FeCl3, CoCl2, and NiCl2, a series of catalyst systems were developed and used to activate the catalytic oxidation of n-octane in the presence of H2O2 as the oxidant in a biphasic IL/H2O system. All systems tested were found to be active under optimum conditions yielding oxygenated products (mainly octanones). The role of the substituents around the triazole ring was to influence catalytic efficiency in terms of conversion of the substrate n-octane and selectivity to oxygenated products (octanols, octanal, octanones, and octanoic acid). In a test for recyclability, recovered IL dissolved catalysts were found to be effective up to three cycles without any significant loss of catalytic activity before leaching to the aqueous phase resulted in loss of activity.

Half-sandwich nickel complexes bearing a variety of mesoionic N-heterocyclic carbene ligands (η5-cyclopentadienyl)-iodo-{1-(R)-3-methyl-4-phenyl-1H-1,2,3-triazol-3-ium-5-yl}nickel; where R = phenyl (3a); 2-ethoxy-2-oxoethyl (3b); propyl (3c); benzyl (3d) were synthesized by the reaction of nickelocene with the respective triazolium salts. The complexes were characterized by HRMS and multi-nuclear NMR, and the solid state structures of 3c and 3d were elucidated by single crystal X-ray diffraction analysis in which both complexes displayed a trigonal planar geometry. As catalysts for the oxidation of n-octane in the presence of oxidants under mild reaction conditions, all the complexes showed activity for the substrate yielding a range of oxygenated products. Under optimized reaction conditions, catalyst 3c with lighter substituents on the triazolium ring exhibited the highest catalytic activity of 15% total conversion to products. With H2O2 as the more productive oxidant, the preferential activation of internal carbons led to the observation of a mixture of octanones as the dominant product stream of the oxidation reaction.

Low-temperature oxidation of bitumen with air in the temperature range of 130–160 °C was investigated. Of particular interest were the addition reactions taking place during oxidation, which contributed to the observed increase in viscosity of oxidized bitumen. During the autoxidation of bitumen, the relative aliphatic to aromatic loss-ratio of hydrogen increased from 18:1 to 30:1 when the temperature was increased from 140 °C to 150 °C and then remained almost the same at 160 °C. It coincided with a bitumen oxidation selectivity change reported in the literature. The hydrocarbon class responsible for most addition reactions during bitumen oxidation is the naphthenic-aromatic class. A model compound oxidation study at 130 °C found no addition products during paraffin oxidation, low addition product selectivity for naphthenic and alkylaromatic compounds, and no measurable oxidation of aromatics without alkyl groups. It was proposed that the dominant pathway for addition reactions of hydrocarbons is hydroge...

Paraffin was mixed with microcrystalline wax at certain temperatures, airflow rate, and time. The catalyst and the catalyst promoter were added, and the oxidation reaction took place. Factors affecting induction period and activation energy, such as the airflow rate, the reaction temperature, the mass of the catalyst, the mass of catalyst promoter, and the reaction time, were also investigated. The induction period and the activation energy could be reduced, and the production's acid number and its saponification number could be improved by increasing the airflow rate and the reaction temperature. The productions can substitute the beeswax.

This paper examines the most important factors that affect the functionalization of light alkanes by means of selective oxidation. The state-of-the-art in paraffin oxidation and the main features that affect the choice of the reactor and the process configuration are discussed.

Department of Chemistry, Dr. Hari Singh Gour University, Sagar-470 003, Madhya Pradesh, India E-mail : drtssrao@yahoo.co. in Manuscript received 28 December 2011, revised 02 May 2012, accepted 07 June 2012 Alkylhydroperoxides formed initially as the products of paraffin oxidation undergo decomposition to give alcohols, ketones etc. The further oxidation of these products yields carboxylic acids. The transition metal salts like stearates of Mn, Co and Cr and acetylacetonates of Mn, Co, Cr, Mo and complexes of metals like Ru, Pd, Ni etc. can accelerate the decomposition. Temperature directly influences the radical decarbonylation and decarboxylation reactions. The rate of C-H bond activation depends not only upon the nature (primary, secondary and tertiary) but also their distance from the chain end. The oxidation of n-butane to maleic anhydride is the only commercialized process of paraffins. Higher rate of oxidation of the partial oxidation products than the starting paraffin and the irreversible deactivation of the catalysts have to be addressed. Selective photo-catalytic oxidation at ambient conditions may be the answer to use the readily available paraffin sources economically.

The sections in this article are Introduction Analyzing the Challenge of Heterogeneously Catalyzed Alkane Oxidation Analysis on a Microscopic Basis of the Critical Steps of Paraffin Oxidation Utilizing Solid Catalysts Utilizing Solid Catalysts Activation of Oxygen and Paraffin Models for the Active Site The Role of Co-Feeds in the Educt Stream The Role of the Crystalline Nature and the Admixture of Different Crystalline Phases for the Catalyst The Role of the Acid–Base Interaction of Reactant and Catalyst Analysis of the Technical Challenges of Paraffin Oxidation Utilizing Solid Catalysts Conversion of Butane to Maleic Anhydride: An Overview of a Mature Technology Manufacturing Technologies for MA from n-Butane The VPO-Catalyst: Structural Basis and Synthetic Pathways The VPO-Catalyst: Reaction Pathways and Potential Active Sites of the Catalyst Propane Oxidation to Acrylic Acid and Acrylonitrile: Getting Closer to a Technical Solution Rutile-Based Structures for Selective Propane Oxidation Complex Bronze Structures Based on Molybdenum for Selective Propane Oxidation Ethane to Acetic Acid: The Search for a Viable Pathway Outlook Acknowledgments Keywords: oxyfunctionalization; solid catalyst; maleic anhydride

Higher aliphatic alcohols (C6–C18) are produced in a number of important industrial processes using petroleum-based raw materials, eg, the Ziegler, oxo, and aldol processes. By far the largest volume synthetic alcohol is 2-ethylhexanol, C8H18O, used mainly in production of the poly(vinyl chloride) plasticizer bis(2-ethylhexyl) phthalate, C24H38O4, commonly called dioctyl phthalate or DOP. Other, lower volume synthetic alcohol application areas include solvents and specialty esters. Keywords: 2-Ethylhexanol; Ziegler process; Alcohols; higher aliphatic; Oxo process; Aldol process; Paraffin oxidation; Guerbet process

Publisher Summary The most studied systems for oxidative propane upgrading are vanadium, vanadium-antimony, vanadium-molybdenum, and vanadium-phosphorus based catalysts. Another family of light paraffin oxidation catalysts are molybdenum based systems, for example, nickel-molybdates, cobalt-molybdates, and various metal-molybdates. Ni–Co-molybdates are viable oxidation catalysts for the activation of light paraffins, such as propane and butanes, to produce the respective olefins. Maximum yields are in the range of 16% at about 80% selectivity. The catalysts activate methylene C–H bonds, abstracting the hydrogen of the substrate in the rate limiting step of the reaction. With propane as feed, propylene is the only first formed product and all the higher oxidized products ensue in subsequent steps after the propylene has been formed. Acrolein is formed from the in situ produced propylene and acrolein is the main intermediate, leading to waste products CO and CO2. Binary molybdates of the formula AMoO4, where A = Ni, Co, Mg, Mn, and/or Zn and some ternary Ni–Co-molybdates promoted with P, Bi, Fe, Cr, V, Ce, K, or Cs, have been recently under study. A specific representative of these systems is the composition Nio.5Co0.5MoO4 that has been recently selected for an in depth kinetic study and whose mechanistic aspects are now further discussed in this chapter.

By computer simulation of the dependencies of the mole numbers of the ketones and alcohols derived from the starting paraffin, of the acids and esters, and in some cases also of the lower alkan-2-ones on the paraffin conversion relative rate constants were determined on the basis of a plausible kinetic model of the paraffin oxidation. The data obtained show that about 67% of the oxidation proceeds via bifunctional primary products. With the aid of the relative rate constants determined a good simulation of the experimental mole number-conversion curves is possible.

1. Industrial tests on the continuous method of paraffin oxidation carried out in the “Twelfth Meeting of the Communist Party USSR” Ufa Oil Refinery have shown that the output of the columns can be doubled without deterioration of the product quality owing to change-over to the new hydrodynamic regime. 2. The continuous oxidation process is easily controlled and may be conpletely automated.

1. The optimum ozone content in air for oxidation of paraffin in the presence of Mn-K soaps of C5−C9 acids is equal to 0.3% by wtif ozonized air is used throughout the course of the whole oxidation process; and is 1.0–1.5% if ozonized air is used only for the duration of the first 30–60 min of oxidation. 2. The combined use of ozone and an accelerator containing manganese offers the possibility of increasing the rate of paraffin oxidation threefold while maintaining the qualities of the oxidation products obtained. 3. On oxidation of paraffin with air containing ozone, the presence of potassium salts does not affect the rate of the oxidation process, nor the composition of the substances formed.

Petroleum utilizing microorganisms in flasks containing enriched seawater exhibited a clear metabolic preference for saturated paraffins in a Louisiana crude oil. The rates of oxidation of these compounds were directly proportional to incubation temperature and roughly doubled with a ten degree increase. A pattern of growth consisting of an initially large rate of saturated paraffin oxidation, followed by a decrease and another increase in rate was observed. The initially large rates were attributed to the metabolism of n-paraffins smaller than C-18. No even or odd chain length preference for n-paraffins was indicated. There was no evidence of utilization for aromatic compounds. Application of a microbial culture to an oil slick under simulated field conditions, clearly showed that microbes could accelerate the removal of a Louisiana crude oil from an oil slick on seawater. The rates of oil removal in outdoor, exposed conditions, were twice as large as the rates of evaporative oil loss. The microbes produced a significant change in oil “stickiness”. Measurements indicated the oil was dispersed through microbial activity. The cells preferentially remained at the oil-water interface during the experimental periods.

1. A method has been worked out for preparing return raw material for the oxidation process, consisting of treating the unsaponifiables with a water solution of the low-molecular organic acids which is obtained in the form of an aqueous condensate in the manufacture of synthetic fatty acids, with separation of the salt solution in an electrical field. 2. The use of a dc electrical field reduces the settling time for unsaponifiables 10- to 12-fold and improves the completeness of separation of sodium salts from unsaponifiables. 3. The use of return raw material which has been treated with acid water makes it possible to stabilize the oxidation process, reduce the oxidation time by a minimum of 30%, and reduce the air consumption by at least a factor of 1.4.

The induction of paraffin oxidation in intact cells of Pseudomonas aeruginosa was investigated. Oxidation of 14 C-heptane by cell-free extracts of adapted cells showed that the activity of whole cells is a reliable reflection of the synthesis of the first enzyme in the degradation of n -alkanes. Induction was significantly affected by glucose and could be completely repressed by malate. The amino acids l -proline, l -alanine, l -arginine, and l -tyrosine exhibited a rather low repressor action. Malonate, a nonrepressive carbon source, allowed gratuitous enzyme synthesis. A number of compounds which did not sustain growth were found to be suitable substitutes for paraffins as an inducer. Among these were cyclopropane and diethoxymethane. The induction studied under conditions of gratuity with the latter compound as an inducer showed immediate linear kinetics only at saturating inducer concentrations. With n -hexane as the inducer, a lag time was always observed, even when high concentrations were used.

Es wurde versucht, Einzelkomponenten aus der Vorlauffettsaure der Paraffinoxydation durch mehrmalige Feinfraktionierung zu isolieren und die verzweigtkettigen von den geradkettigen Fettsauren zu trennen auf Grund von Harnstoff-Additionsverbindungen der letzteren. Unter Einhaltung bestimmter Destillationsbedingungen war die Isolierung der Fettsauren moglich. Dagegen war die quantitative Trennung der Iso-Sauren mit Harnstoff nur teilweise erfolgreich, doch konnten auf alle Falle die Iso-Sauren in den Rest-Fettsauren angereichert werden. Studies on Isolation of Single Components of Paraffin Oxidation It was tried to isolate single components from the first run of fatty acids of the paraffine oxydation by repeated fractional distillation, and to separate the branched-chain from the straightchain fatty acids by addition compounds of the latter with urea. Under certain conditions of fractional distillation the isolation of fatty acids was possible. The quantitative separation of iso-acids with urea was only partly successful, but in any case the iso-acids could be concentrated in the tails.

Paraffins are found in almost every organism, plants (2), animals (13), and microorganisms (14). The most common biological source of paraffins appears to be the surface lipids of plants (2), the chain length of the most abundant paraffin being most often C,9 or C31. These natural paraffins can be readily catabolized by soil organisms (5) and to a limited extent by anlimals (6). The mechanism of paraffin oxidation was elucidated with bacteria (12) and with enzymes isolated from them (4,15,16). Young leaves of many plants readily synthesize paraffins from fatty acids (8). Experiments on the time course of incorporation of labeled substrates into paraffins of Brassica oleracea failed to show any turnover, possibly because the paraffins are ejected onto the surface of the leaves as soon as they are synthesized (7). Attempts to show catabolism by providing Co, paraffin to excised leaves, leaf tissue slices, or leaf homogenates failed. The extremely low solubility of these very long paraffins, and the resulting lack of uptake made it almost impossible to find out whether plants possess the capacity to oxidize their natural paraffins. In order to circumvent these problems a much smaller paraffin, hexadecane-l-14C, was used as substrate. This communication describes experimental results which show that plants do possess the ability to oxidize the terminal methyl carbon of this paraffin to a carboxyl group. Hexadecane-l-'4C (47.2 mc/mmole, Nuclear-Chicago) contained polar impurities and was therefore purified by column chromatography on activated SilicAR cc-4 100 to 200 mesh (Mallinckrodt Chemical Works. St. Louis, Missouri) with hexane as the solvent (9). The purified hexadecane-l-14C contained no radiochemical impurity as determined by thin-layer chromatography. A sample of this labeled paraffin (50 juc) was dissolved in 4 to 5 ml ethyl ether and 3 (rops of Tween-20 were added. The ether was evaporated with a stream of nitrogen, and the residue shaken with 10 ml of water to give a stable emulsion of the paraffin. Young leaves of broccoli, pea and tobacco, second from the apex and not fully expanded, were sliced (2 X 10 mm) with a razor blade. These slices when incubated with the purified hexadecane, produced radioactive lipids more polar than paraffin as shown in table I. Although Table I. Oxidation of Hexadecane-1-l4C by Leaf Slices of Broccoli, Pea, and Tobacco In experiment 1, 1 g of leaf slices was incubated with 2 X 106 cpm hexadecane-l-14C for 4 hr at 30° in 3 ml water. In experiment 2, 3 g of pea hypocotyl slices were incubated with 4 X 106 cpm hexadecane-l-14C for the periods indicated at 30° in 3 ml water. At the end of the incubation period, tissue slices were ground in a 2:1 mixture of chloroform and methanol, and the total lipids extracted as described before (9). Aliquots of the total lipids were chromatographed on silica gel G plates with hexane as the developing solvent in an unlined tank. Only paraffins migrated with the solvent front. The oxidation products such as fatty alcohols, acids and phospholipids remained at the origin. The radioactivity in this fraction is shown in the table.