Isomerization studies: III. decarbonylation of oleoyl chloride preparation of C19 dicarboxylic acids

Mixtures of siomeric C₁₇ diene hydrocarbons were obtained when oleoyl chloride was decarbonylated in the presence of a transition metal catalyst. The choice of catalyst determined the composition of diene mixture produced. Diene mixtures were characterized as a mixture of conjugated and 1,4- dienes, or as a mixture of isolated double bond dienes. Carboxylation of the conjugated C₁₇ diene by hydroformylationoxidation procedure gave a C₁₈ monocarboxylic acid as the major product, whereas with nonconjugated C₁₇ diene, the major product was a C₁₉ dicarboxylic acid. Application of the Koch carboxylation procedure to C₁₇ diene mixtures gave a C₁₉ dicarboxylic acid mixture as the major product. This latter acid mixture was structurally different from diacids obtained from the hydroformylation-oxidation procedure.     

Co- and terpolymerizations of α-olefins and dienes with MgH2-supported Ziegler catalyst

Copolymerizations of ethylene or propylene with butadiene, 1,5-hexadiene or 1,7-octadiene by MgH₂/TiCl₄-AlEt₃ catalyst system were carried out. The effect of diene concentration in the reaction medium for each polymerization system on catalytic activity was observed. The compositions of the obtained copolymers were evaluated and the reactivity ratios were determined. Ethylene-propylene-diene terpolymerizations with the same catalyst system were also investigated.     

Application of Methoxy-Bromomercuric-Adduct Fractionation to the Study of Cyclic Fatty Acid Monomers from a Heated Linseed Oil

A linseed oil was heated at 275° C for 12 hr under nitrogen. The triglycerides were isolated from the polymers by gel permeation chromatography on 2μ-styragel columns using tetrahydrofuran (THF) as solvent. One part of the isolated triglyceride fraction was submitted to HPLC on a C₁₈ reverse phase column. The resulting 8 fractions were transformed into methyl esters and hydrogenated on PtO₂ The content of cyclic fatty acid monomers (CFAM) in the different hydrogenated fractions was determined by gasliquid chromatography (GLC) on a Silar-10 C column. The other part of the isolated triglyceride fraction was submitted to the action of BF₃/MeOH. The resulting methyl esters were fractionated by thin-layer chromatography of the corresponding methoxybromomercuric adducts. Five bands were obtained using a mixture of hexane: dioxane (60:40) as the solvent system. A band between the diene and the triene bands contained 40.6% of the total cyclic fatty acid monomers (CFAM) while the diene and the monoene band contained respectively 38.9 and 11.2% of these cyclic components. The diene band and the band between the diene and the triene bands were hydrogenated on PtO₂ The structures of the resulting hydrogenated cyclic fatty acid monomers were studied using a gas-liquid chromatograph coupled with a mass spectrometer (GC-MS).     

Regio- and stereochemistry of the first insertion step in the 1,3-butadiene polymerization catalyzed by CpTiCl3-MAO

CpTiCl₃-MAO (methylaluminoxane) catalytic system promotes the butadiene polymerization leading to 85% of 4,1-cis polymer. The generally well accepted homopolymerization mechanism involves a diene insertion on a π-allylic terminal growing chain. In α-olefin-diene copolymerizations, diene monomer can also insert on a σ carbon-metal bond.In order to simulate an insertion of a conjugated diene on a σ chain, experimental and theoretical studies, relative to the first insertion step, are reported. Unexpectedly 56% of 1,2-primary and 44% of 4,1-trans first inserted units were obtained, by using as catalyst CpTiCl₃/MAO/Al(¹³CH₃)₃. The experimental results were rationalized by DFT (Density Functional Theory) calculations, by including a solvent molecule coordinated to the catalytic site during the first insertion step.     

Sperm oil replacements from selectively hydrogenated soybean and linseed esters: Special lubricants

Soybean and linseed oils were selectively hydroenated with copper-on-silica gel catalyst. The linolenate content of the oils was reduced to diene and monoene with no appreciable increase in saturates. Hydrogenated soybean oils contained 68–76% monoene, 11–18% diene, 0% conjugated diene and triene, 1–6% conjugatable diene, 0–0.3% conjugatable triene, and 23–40% isolatedtrans double bonds. Hydrogenated linseed oils contained 44–54% monoene, 35–45% diene, 0% conjugated diene and triene, 0–7% conjugatable diene, 0–02% conjugatable triene, and 44–59% isoaltedtrans double bonds. Esters of fatty acids, derived from these selectively hydrogenated oils, were prepared with trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, ethylene glycol, C₁₈ saturated cyclic alcohols, primary C₁₂–C₁₈ saturated (nC₁₂, nC₁₄, nC₁₆, nC₁₈) alcohol, and primary C₁₆–C₁₈ saturated (nC₁₆, nC₁₈) alcohol blends. Measurements of viscosities and of smoke, flash, and fire points indicate that these esters are possible replacements for sperm oil. Certain of them, after sulfurization, also have potential as extreme pressure lubricant additives. Presented at the AOCS meeting in Philadelphia, September 1974.     

Dynamic simulation and experimental evaluation of EPDM synthesis with ET(IND)2ZRCL2/MAO catalyst system

A mathematical model for the homogeneous terpolymerization of ethylene–propylene–diene (EPDM) in a semibatch reactor using Et(Ind)₂ZrCl₂/MAO as a catalyst system was developed and reported herein. In this study, we developed a kinetic model in order to explain the catalyst and EPDM properties such as catalyst activity, weight‐average molecular weight, and terpolymer composition, which were experimentally and theoretically obtained. For this system, a lower E/P feed ratio leads to a lower molecular weight and a broader initial molecular weight distribution, while the increase in diene concentration leads to a decrease in the catalyst activity without broadening the MWD of the resulting polymers. The proposed model accounts for these experimental trends and for some data in the literature.     

Copolymers of ethylene with bicyclic dienes

The copolymerization of ethylene (E) with dicyclopentadiene (DCP), ethylidene norbornene (ENB) or methyl endomethylene hexahydronaphthalene (MEHN) by ZIEGLER -NATTA catalysts in presence of H₂ affords low-mol.-wt. products over a wide range of unsaturation. In this paper some characteristic features of the copolymerization and some physical properties of the raw products are discussed. For the catalytic system VOCI₃-Al₂Et₃Cl₃ differences in catalyst efficiency, copolymer composition, diene incorporation and viscosity can be seen as a function of type and amount of diene monomer. Physical properties of the copolymers are strongly dependent on composition. Incorporation of dience results in lowered melting points of the parent PE. In case of E-DCP and E-ENB the materials become amorphous beyond 15-20 mole-% diene. At this composition minimum glass transition temperatures are seen.     

The production of ethene/propene/5-ethylidene-2-norbornene terpolymers using metallocene catalysts: Polymerization,characterization and properties of the metallocene EPDM

Metallocene catalysts Et(Ind)₂ZrCl₂/MAO and Et(Ind)₂HfCl₂/MAO were used in ethene/propene copolymerization and in ethene/propene/5-ethylidene-2-norbornene (E/P/ENB) terpolymerization. The copolymerization activity of the Et(Ind)₂ZrCl₂/MAO system was 20 × 10³ kg_polym/mol_Mt *h, the Et(Ind)₂HfCl₂/MAO yielding 5 × 10³ kg_polym/mol_Mt *h. The polymerization activity decreased with diene addition, but this effect was significant only at very large diene feeds. The catalysts incorporated diene readily. Materials with an ethene content of 55 to 70 mol % and an ENB content of 2 to 16 mol % were produced. Et(Ind)₂HfCl₂ produced a considerably higher molar mass material than the Et(Ind)₂ZrCl₂ catalyst. The molar mass distributions were narrow. Copolymers and terpolymers with up to 3 mol % ENB content had some crystallinity. Copolymer T_gs were between −59°C and −55°C. The terpolymer glass transition temperature rose 1.5°C per wt % of ENB in the polymer. Polymer characteristics reported include composition, molar mass distribution, melt flow rate, density, and thermal behavior. The dynamic mechanical and rheological properties of the materials in comparison with commercial E/P/ENB terpolymers are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 35–44, 1997     

Unlubricated rolling and sliding wear against steel of carbon‐black‐reinforced and in situ cured polyurethane containing ethylene/propylene/diene rubber compounds

The dry rolling and sliding friction and wear of ethylene/propylene/diene rubber containing carbon black and in situ cured polyurethane (EPDM+PUR_CB) were studied. For rolling and sliding tests against steel counterparts, different experimental conditions and tribotests were selected. The apparent network properties and phase structures of the rubbers were derived from dynamic mechanical thermal analysis and atomic force microscopy results. It was concluded that in EPDM+PUR_CB, both rubber phases, present in a 1 : 1 ratio, were continuous (interpenetrating network). The coefficient of friction (COF), specific wear rate (W_s), and heat development during the tribotests were determined. The carbon black and polyurethane contents did not much influence the COF in rolling wear tests. W_s of the ethylene/propylene/diene rubber containing carbon black went through a minimum as a function of the carbon black content. W_s of the EPDM+PUR_CB compounds decreased monotonously with an increasing amount of carbon black. The incorporation of polyurethane into the ethylene/propylene/diene rubber compounds decreased the resistance to rolling wear markedly. With carbon black filling of the ethylene/propylene/diene rubber–polyurethane compound, the COF and W_s increased and dramatically decreased, respectively, under sliding wear. The wear mechanisms were inspected with scanning electron microscopy and discussed as a function of recipe modifications and changes in the testing conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Initiation of lipid peroxidation by a peroxidase/hydrogen peroxide/halide system

A lactoperoxidase/H₂O₂/halide system caused the initiation of linoleate peroxidation as indicated by diene conjugation. Coupled lipid peroxidation was accelerated by iodide, chloride and bromide ions at pH 4.0 and 6.2. No peroxidation occurred in the presence of H₂O₂ or lactoperoxidase alone. The rate of linoleate peroxidation by lactoperoxidase in the presence of chloride depended on the concentration of H₂O₂. Linoleate peroxidation by the enzymatic system was inhibited by high concentration of H₂O₂ by methionine, tryptophan and BHT. Oxygen was absorbed during peroxidation and the major products were the 13-hydroperoxides. The mechanisms of the initiation of lipid peroxidation by a peroxidase/H₂O₂/halide system are discussed.     

An improved synthesis of (24R)-3β-(2H-Tetrahydropyran-2-yloxy)cholesta-5,7-diene-24,25-diol – a key intermediate in the synthesis of (24R)-24,25-dihydroxyvitamin D3

A multistep procedure for the conversion of ergosterol into the tetrahydropyranyl ether of (24R)-24,25-dihydroxyprovitamin D₃ using 1,4-dihydrophthalazine-1,4-dione as diene protecting agent was compared with an established route, which uses 4-phenyl-1,2,4-triazoline-3,5-dione for the protection of the diene system. The disclosed reaction sequence allows to double the overall yield. The 1,4-dioxo-1,2,3,4-tetrahydrophthalazin-2,3-ylene group proved to be the better diene protecting group in the ozonolytic degradation of the ergosterol side chain. Maintaining the protecting group in the next reaction steps offered further advantages by diminishing the air and light sensitivity of the intermediates.     

Dynamic simulation and experimental evaluation of EPDM terpolymerization with vanadium-based catalyst

The development of a simplified kinetic model describing some effects observed in catalyzed olefin terpolymerization is presented. Based on the method of moments, the model describes the influence of Al/V ratio and diene concentration on reaction yield and on polymer characteristics such as molecular weight, ethylene incorporation, and polydispersity. In order to verify the model validity, the terpolymerization reactions were performed using VOCl₃–Al₂Et₃Cl₃ systems and 2-ethylidenebi-cyclo[2.2.1]hept-5-ene (ENB) as diene. The results of dynamic simulation fit well the experimental data for Al/V up to 15, but the model fails under high diene concentration, where branching reactions, neglected by reason of simplification, become significant. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1173–1189, 1998     

Fluorination Studies on Glycyrrhetic Acid Derivatives

Attempts to introduce a fluorine atom directly at the C-3 position of the triterpenoidal glycyrrhetic acid 1 by reacting the tosylate 2 with KF, or methyl glycyrrhetate 5 with Et₂NCF₂CHCIF, failed. The ring A olefin 3 and the rearrangement product 4 were obtained. The homoannular diene 7 was treated with NOF, but only nitroso-fluorine compounds 8, 9 were isolated. Nitrosyl fluoride was also reacted with olefin 3 . A difluoro compound 10 and the expected 2-keto-3α-fluoro compound 11 were obtained. The above two olefins were also reacted with bromine fluoride. Although the diene 7 gave only fluorine-free compounds 13, 14 , the expected fluoro-bromine compound 16 was obtained from 3 . When the 2β-fluoro-3α-bromo compound was treated with Bu₃SnH, the bromine atom was replaced by hydrogen and the 2β-fluoro compound 17 was formed.     

Comparison of homogeneous and heterogeneous palladium hydrogenation catalysts

Mechanistic and kinetic studies of Pd-catalyzed hydrogenation at atmospheric pressure and 30–100 C were carried out with methyl sorbate, methyl linoleate and conjugated linoleate. Homogeneous Pd catalysts and particularly Pd-acetylacetonate [Pd(acac)₂] were significantly more selective than Pd/C in the hydrogenation of sorbate to hexanoates, mainlytrans-2-hexenoate. Relative rate constants for the different parallel and consecutive reactions, determined by computer simulation, indicated that the low diene selectivity of Pd/C can be dattributed to a significant direct reduction of sorbate to hexanoate. The similar behavior of PdCl₂ to that of Pd/C suggests that Pd(II) was initially reduced to Pd(O). Valence stabilization of PbCl₂ by adding DMF or a mixture of Ph₃P and SnCl₂ increased the diene selectivity but decreased the activity. Stabilization of Pd(acac)₂ with triethylaluminum (Ziegler catalyst) resulted in increased activity but decreased selectivity. The kinetics of methyl linoleate hydrogenation showed that although Pd(acac)₂ was only half as active as Pd/C, their respective diene selectivity was similar (10.4 and 9.6). The much greater reactivity of conjugated compared with unconjugated linoleate toward Pd(acac)₂ suggests the possible formation of conjugated dienes as intermediates that are rapidly reduced and not detected in the lipid phase during hydrogenation.     

Diastereo‐ and Enantioselective Synthesis of trans‐2,3‐Disubstituted 2,3‐Dihydropyran‐4‐one Derivatives

trans‐Diastereoselective hetero‐Diels–Alder reactions took place in the presence of SiCl₄/activator systems. The reactions of aldehydes with a derivative of Danishefsky’s diene afforded the corresponding pyrones with high yields and diastereoselectivity upon activating SiCl₄ with suitable neutral Lewis bases. Aldol intermediates deriving from a Mukaiyama‐type pathway were isolated in many cases. The employment of a chiral activator allowed us to convert Danishefsky’s diene (or its disubstituted derivative) into both aldols and pyrones in good to high enantiomeric excesses.     

Synthesis and characterization of EPDM films

A series of ethylene–propylene-2-ethylidenebicyclo[2.2.1]hept-5-ene terpolymers have been prepared using the VOCl₃/Al₂Et₃Cl₃ catalyst under various initial Al/V ratios and diene concentrations. The V/C and Al/V ratios in EPDM films were determined by Rutherford backscattering spectrometry. The concentration of incorporated vanadium increases with the increase of the iodine number, i.e., with the number of double bonds in the polymer. However, the concentration of incorporated V in the terpolymers remains relatively low, which is attributed to the small percentage of V(III) active species due to the presence of the diene. On the other hand, the Al/V molar ratio in the terpolymers was seen to be roughly constant (between 6 and 8), independent of the iodine number and of the initial Al/V molar ratio in the reaction mixture. The polymerization yield was seen to increase with the augmentation of the initial Al/V ratio and of the diene concentration, until reaching a maximum of about 500 g polymer/g V. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 535–541, 1998     

Homologation of Monoterpenoids into New Sesquiterpenoids via Tandem Isomerisation/Claisen Rearrangement Reactions with Three‐Component Ruthenium Catalysts,and Ru(methallyl)2(COD) Revealed by High Throughput Screening Techniques

A catalytic system B based on a ruthenium source Ru₃(CO)₁₂, a bulky imidazolinium salt and Cs₂CO₃ appears very efficient for the transformation of a 1,7‐diene into a γ,δ‐unsaturated aldehyde via tandem isomerisation/Claisen reactions. 1,6‐Dienes arising from the terpenoids menthone and myrtenal were selectively transformed into the corresponding unsaturated aldehydes with catalyst B . High throughput experiments were undertaken to evaluate other multicomponent catalysts: metal source/ligand/base for these tandem reactions. An unexpected catalyst was found to be Ru(methallyl)₂(COD) which can operate without additional ligand or reagent.     

Effect of segment structure on the thermal stability of CPVC in the Gas–Solid PVC chlorination process

The chlorination of the polyvinyl chloride resin with different ratios of  CH₂ , CHCl₂, and CCl₂ was carried out through a gas–solid process by varying the temperature, reaction time, and chlorine concentration. The rheological properties and thermal stability of the resin were characterized. ¹³C NMR was used to characterize the segment structure of the resin. In addition, conjugated diene structure was determined by UV–Visible to study its chlorination process. The results show that  CCl₂ units in the structure promote the dehydrochlorination of CPVC, forming a conjugated diene structure and reducing the rheological properties and thermal stability. In contrast, the formation of  CHCl in the chlorination process increased the thermal stability of the resin. Moreover, a structure-effect relationship between the structure and performance has been established, and a stepwise process of chlorination was obtained by analyzing the changes of the structure segment content at different stages.     

An Electron‐Deficient Diene as Ligand for Palladium‐Catalyzed Cross‐Coupling Reactions: An Efficient Alkylation of Aryl Iodides by Primary and Secondary Alkylzinc Reagents

An electron‐deficient diene, L₁ , was found to be an effective ligand in facilitating palladium‐catalyzed Negishi couplings involving primary and secondary alkylzinc reagents. The reactions took place readily at 60 °C in THF with 5 mol% of a catalyst generated in situ from bis(acetonitrile)palladium dichloride [PdCl₂(MeCN)₂] and L₁ , and functional groups such as chloro, bromo, etc. attached to phenyl ring as well as β‐H atoms adjacent to the reaction site were well tolerated. The problematic isomerizations in secondary alkyzinc reagents involved in the reactions reported in the literature were also observed in our system when isopropylzinc chloride was employed alone as the nucleophile. However, the isomerization was significantly suppressed when i‐Pr₂Zn was utilized in the presence of L₁ .     

Ethylene/propylene/5-ethylidene-2-norbornene

Summary Ethylene/propylene/5-ethylidene-2-norbornene(ENB) terpolymerization was carried out with a highly active Ti catalyst system(MgCl₂/TiCl₄/C₆H₅COOC₂H₅ (EB) — AliBu₃/di-iso-amyl ether (IAE)). The obtained terpolymer could be vulcanized with sulfur, but the increase of torque value through the vulcanization measured by curelastometer for the terpolymer obtained with this catalyst was considerably lower than that for the terpolymer obtained with the conventional VOCl₃ catalyst system. It was suggested that lower torque value would be attributed to the heterogeneous diene distribution in the obtained terpolymer, particularly lower ENB content in the high molecular weight fraction.