Olefinic Alcohols Research Articles

Semi‑hydrogenation of acetylenic alcohol to olefinic alcohol catalyzed by Pd nanoparticles embedded in nitrogen-enriched porous carbon derived from ZIF-8

Semi‑hydrogenation of acetylenic alcohol to olefinic alcohol catalyzed by Pd nanoparticles embedded in nitrogen-enriched porous carbon derived from ZIF-8

Validation of octane hyperboosting phenomenon in prenol and structurally related olefinic alcohols

Hyperboosting is a recently discovered phenomenon in which the research octane number (RON) of a blend is higher than both the neat blendstock and the neat fuel it was blended into. RON is a measure of a fuel’s resistance to knock, and knock is a cause of engine inefficiency. Blends which exhibit hyperboosting are blends in which an overall improvement in engine efficiency may be expected. The first discovery of hyperboosting came from blending experiments in which prenol was blended into several different base fuels. Here, ignition delay time (IDT) measurements taken using a commercially available constant volume combustion chamber called the Advanced Fuel Ignition Delay Analyzer (AFIDA) are presented. The data show that some prenol blends have longer IDTs (lower reactivity) than either neat prenol or the base fuel, providing further evidence of hyperboosting. Additionally, more blending data is presented in which the base fuel is varied, which allows for a better understanding of hyperboosting sensitivity to chemical classes. The data indicate that aromatics may inhibit, and branched alkanes may enhance the magnitude of hyperboosting observed. Enthalpy of vaporization estimates are also given for several molecules which are blended into a 4-component surrogate. These estimates are derived from Equation of State simulations and reveal that there is no observable correlation between hyperboosting and enthalpy of vaporization. Blending data for molecules which share structural similarities with prenol are also presented. Structure property relationships are suggested, in which the double bond motif of prenol seems to play an important role in hyperboosting. This may help to understand hyperboosting and its underlying mechanism. Lastly, blending curves of surrogate blends with prenol experienced hyperboosting under lean (Homogeneous Charged Compression Ignition-HCCI) operating conditions, which validates that hyperboosting is not an artifact of the octane test methods, but inherent to the properties of prenol.

Microbial production of high octane and high sensitivity olefinic ester biofuels

BackgroundAdvanced spark ignition engines require high performance fuels with improved resistance to autoignition. Biologically derived olefinic alcohols have arisen as promising blendstock candidates due to favorable octane numbers and synergistic blending characteristics. However, production and downstream separation of these alcohols are limited by their intrinsic toxicity and high aqueous solubility, respectively. Bioproduction of carboxylate esters of alcohols can improve partitioning and reduce toxicity, but in practice has been limited to saturated esters with characteristically low octane sensitivity. If olefinic esters retain the synergistic blending characteristics of their alcohol counterparts, they could improve the bioblendstock combustion performance while also retaining the production advantages of the ester moiety.ResultsOptimization of Escherichia coli isoprenoid pathways has led to high titers of isoprenol and prenol, which are not only excellent standalone biofuel and blend candidates, but also novel targets for esterification. Here, a selection of olefinic esters enhanced blendstock performance according to their degree of unsaturation and branching. E. coli strains harboring optimized mevalonate pathways, thioester pathways, and heterologous alcohol acyltransferases (ATF1, ATF2, and SAAT) were engineered for the bioproduction of four novel olefinic esters. Although prenyl and isoprenyl lactate titers were limited to 1.48 ± 0.41 mg/L and 5.57 ± 1.36 mg/L, strains engineered for prenyl and isoprenyl acetate attained titers of 176.3 ± 16.0 mg/L and 3.08 ± 0.27 g/L, respectively. Furthermore, prenyl acetate (20% bRON = 125.8) and isoprenyl acetate (20% bRON = 108.4) exhibited blend properties comparable to ethanol and significantly better than any saturated ester. By further scaling cultures to a 2-L bioreactor under fed-batch conditions, 15.0 ± 0.9 g/L isoprenyl acetate was achieved on minimal medium. Metabolic engineering of acetate pathway flux further improved titer to attain an unprecedented 28.0 ± 1.0 g/L isoprenyl acetate, accounting for 75.7% theoretical yield from glucose.ConclusionOur study demonstrated novel bioproduction of four isoprenoid oxygenates for fuel blending. Our optimized E. coli production strain generated an unprecedented titer of isoprenyl acetate and when paired with its favorable blend properties, may enable rapid scale-up of olefinic alcohol esters for use as a fuel blend additive or as a precursor for longer-chain biofuels and biochemicals.

Segmented Polyurethanes and Thermoplastic Elastomers from Elemental Sulfur with Enhanced Thermomechanical Properties and Flame Retardancy

AbstractThe production of elemental sulfur from petroleum refining has created a technological opportunity to increase the valorization of elemental sulfur by the creation of high‐performance sulfur based plastics with improved thermomechanical properties, elasticity and flame retardancy. We report on a synthetic polymerization methodology to prepare the first example of sulfur based segmented multi‐block polyurethanes (SPUs) and thermoplastic elastomers that incorporate an appreciable amount of sulfur into the final target material. This approach applied both the inverse vulcanization of S8 with olefinic alcohols and dynamic covalent polymerizations with dienes to prepare sulfur polyols and terpolyols that were used in polymerizations with aromatic diisocyanates and short chain diols. Using these methods, a new class of high molecular weight, soluble block copolymer polyurethanes were prepared as confirmed by Size Exclusion Chromatography, NMR spectroscopy, thermal analysis, and microscopic imaging. These sulfur‐based polyurethanes were readily solution processed into large area free standing films where both the tensile strength and elasticity of these materials were controlled by variation of the sulfur polyol composition. SPUs with both high tensile strength (13–24 MPa) and ductility (348 % strain at break) were prepared, along with SPU thermoplastic elastomers (578 % strain at break) which are comparable values to classical thermoplastic polyurethanes (TPUs). The incorporation of sulfur into these polyurethanes enhanced flame retardancy in comparison to classical TPUs, which points to the opportunity to impart new properties to polymeric materials as a consequence of using elemental sulfur.

Synergistic Relay Reactions To Achieve Redox‐Neutral α‐Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis

AbstractHerein, we report a ruthenium‐catalyzed redox‐neutral α‐alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone‐type “carbanions” and active protons in a one‐pot reaction, and at the same time achieves the first Grignard‐type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.

Synergistic Relay Reactions To Achieve Redox‐Neutral α‐Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis

Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type "carbanions" and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.

Carbonylation and Olefination of Alcohols

Key words carbonylation - olefination - alcohols - palladium catalysis

Hemilabile Benzyl Ether Enables γ-C(sp3)-H Carbonylation and Olefination of Alcohols.

Pd-catalyzed C(sp3)-H activation of alcohol typically shows β-selectivity due to the required distance between the chelating atom in the attached directing group and the targeted C-H bonds. Herein we report the design of a hemilabile directing group which exploits the chelation of a readily removable benzyl ether moiety to direct γ- or δ-C-H carbonylation and olefination of alcohols. The utility of this approach is also demonstrated in the late-stage C-H functionalization of β-estradiol to rapidly prepare desired analogues that required multi-step syntheses with classical methods.

Pd Nanoparticles Stabilized by Hypercrosslinked Polystyrene Catalyze Selective Triple C-C Bond Hydrogenation and Suzuki Cross-Coupling

This paper describes the synthesis of Pd-containing catalysts based on nonfunctionalized hypercrosslinked polystyrene via impregnation with Pd acetate. Developed Pd nanoparticulate catalyst allowed achieving conversion of aryl halide up to 90% in Suzuki cross-coupling reaction under mild conditions and at the absence of phase-transfer agents. During the selective hydrogenation of triple C-C bond of 2-methyl-3-butyn-2-ol, up to 96% selectivity with respect to corresponding olefinic alcohol was found at 95% conversion. The influences of the procedure of catalyst synthesis like precursor decomposition and reductive activation method on Pd nanoparticle formation are discussed.

Encapsulation of Crabtree's Catalyst in Sulfonated MIL-101(Cr): Enhancement of Stability and Selectivity between Competing Reaction Pathways by the MOF Chemical Microenvironment.

Crabtree's catalyst was encapsulated inside the pores of the sulfonated MIL‐101(Cr) metal–organic framework (MOF) by cation exchange. This hybrid catalyst is active for the heterogeneous hydrogenation of non‐functionalized alkenes either in solution or in the gas phase. Moreover, encapsulation inside a well‐defined hydrophilic microenvironment enhances catalyst stability and selectivity to hydrogenation over isomerization for substrates bearing ligating functionalities. Accordingly, the encapsulated catalyst significantly outperforms its homogeneous counterpart in the hydrogenation of olefinic alcohols in terms of overall conversion and selectivity, with the chemical microenvironment of the MOF host favouring one out of two competing reaction pathways.

Encapsulation of Crabtree's Catalyst in Sulfonated MIL‐101(Cr): Enhancement of Stability and Selectivity between Competing Reaction Pathways by the MOF Chemical Microenvironment

AbstractCrabtree's catalyst was encapsulated inside the pores of the sulfonated MIL‐101(Cr) metal–organic framework (MOF) by cation exchange. This hybrid catalyst is active for the heterogeneous hydrogenation of non‐functionalized alkenes either in solution or in the gas phase. Moreover, encapsulation inside a well‐defined hydrophilic microenvironment enhances catalyst stability and selectivity to hydrogenation over isomerization for substrates bearing ligating functionalities. Accordingly, the encapsulated catalyst significantly outperforms its homogeneous counterpart in the hydrogenation of olefinic alcohols in terms of overall conversion and selectivity, with the chemical microenvironment of the MOF host favouring one out of two competing reaction pathways.

Stereoselective Total Synthesis of Proposed Structure of Stagonolide D

The stereoselective total synthesis of the proposed structure of naturally occurring nonenolide stagonolide D has been achieved using D-mannitol as the starting material. The latter has been utilized for the preparation of both the olefinic alcohol segment and the olefinic acid segment of the target molecule. The synthetic sequence involves asymmetric epoxidation and ring-closing metathesis as the key steps.

Direct Olefination of Alcohols with Sulfones on Pt/C Nanoparticles

Direct Olefination of Alcohols with Sulfones on Pt/C Nanoparticles

ChemInform Abstract: Direct Catalytic Olefination of Alcohols with Sulfones.

The synthesis of terminal, as well as internal, olefins was achieved by the one-step olefination of alcohols with sulfones catalyzed by a ruthenium pincer complex. Furthermore, performing the reaction with dimethyl sulfone under mild hydrogen pressure provides a direct route for the replacement of alcohol hydroxy groups by methyl groups in one step.

Racemization of Olefinic Alcohols by a Carbonyl(cyclopentadienyl)ruthenium Complex: Inhibition by the Carbon-Carbon Double Bond

In this article, racemization of various olefinic sec-alcohols by Ru(CO)(2)((5)-C5Ph5)Cl was investigated. The racemization of three aliphatic sec-alcohols with different chain lengths containing terminal double bonds was studied. A dramatic decrease of the racemization rate was found for these sec-alcohols compared to that of the corresponding saturated substrates. The slow racemization rate of the former alcohols is ascribed to coordination of the double bond to the ruthenium centre, which blocks the free site needed for -hydride elimination. This mechanism was supported by a recent study, in which 5-hexen-2-ol was found to form an alkoxycarbonyl complex having the double bond coordinated to the ruthenium atom. Aliphatic sec-alcohol substrates with a di- or trisubstituted double bond were found to give a lower degree of inhibition of the racemization rate than the substrates with a monosubstituted double bond.

ChemInform Abstract: First Total Synthesis of the E‐ and Z‐Isomers of Cytospolide‐D.

Abstract A simple, convergent, and efficient approach for the total synthesis of the bioactive E- and Z-isomers of cytospolide-D is described. The key features of the synthetic strategy include stereoselective methylation, regioselective epoxide opening, olefin cross-metathesis, and a Yamaguchi protocol reaction for the formation of the E-olefinic geometry of the 10 membered ring; Steglich esterification and ring-closing metathesis reaction for the formation of the 10 membered ring with a Z-olefinic geometry in the skeleton. l -Malic acid was used as a chiral pool starting material for the construction of the olefinic acid fragment while d -mannitol was used as a chiral pool starting material for the building of the olefinic alcohol fragment.

Stereoselective approach to the DEF ring system of terpendole E

Diastereoselective construction of a DEF ring model of terpendole E, a M phase-specific antimitotic natural product, has been achieved from a known bicyclic keto ester by a 10-step (or 12-step) sequence that features an efficient one-pot intramolecular etherification of an olefinic alcohol with mCPBA. The synthesis proceeded in an excellent overall yield of 36% through 10 steps or in 56% via 12 steps which involved a highly diastereoselective reduction of a ketone derived from an undesired diastereomeric alcohol intermediate.

First total synthesis of the E- and Z-isomers of cytospolide-D

A simple, convergent, and efficient approach for the total synthesis of the bioactive E- and Z-isomers of cytospolide-D is described. The key features of the synthetic strategy include stereoselective methylation, regioselective epoxide opening, olefin cross-metathesis, and a Yamaguchi protocol reaction for the formation of the E-olefinic geometry of the 10 membered ring; Steglich esterification and ring-closing metathesis reaction for the formation of the 10 membered ring with a Z-olefinic geometry in the skeleton. l-Malic acid was used as a chiral pool starting material for the construction of the olefinic acid fragment while d-mannitol was used as a chiral pool starting material for the building of the olefinic alcohol fragment.

Synthesis of rumphellaone A via epoxy nitrile cyclization

The first enantioselective total synthesis of rumphellaone A, a cytotoxic 4,5-seco-caryophyllane isolated from the gorgonian coral Rumphella antipathies, has been achieved from a known olefinic alcohol by a 16-step sequence involving Stork's epoxy nitrile cyclization as the key step to concomitantly install a cyclobutane ring and three contiguous stereogenic centers contained in the molecule.

The stereoselective total synthesis of (−)-achaetolide

The stereoselective total synthesis of (−)-achaetolide is described in a convergent manner. Grignard addition, Wittig homologation, acetate aldol and ring closing metathesis reactions were the key steps involved. The required olefinic alcohol fragments were synthesized from a single chiral pool material 2-deoxy-d-ribose and olefinic acid fragment was prepared from acetate aldol reaction. Both the olefinic acid and alcohols were prepared in a concise method.