Synthesis Of Diols Research Articles

Photocatalytic dihydroxylation of light olefins to glycols by water

Aliphatic diols such as ethylene and propylene glycol are the key products in the chemical industry for manufacturing polymers. The synthesis of these molecules usually implies sequential processes, including epoxidation of olefins using hydrogen peroxide or oxygen with subsequent hydrolysis to glycols. Direct hydroxylation of olefins by cheap and green oxidants is an economically attractive and environmentally friendly route for the synthesis of diols. Here, we report a photocatalytic reaction for the dihydroxylation of ethylene and propylene to their glycols at room temperature using water as the oxidant. The photocatalyst contains Pd clusters stabilized by sub-nanometric polyoxometalate with TiO2 as the host material. Under light irradiation, it results in production rates of ethylene glycol and propylene glycols of 146.8 mmol·gPd−1·h−1 and 28.6 mmol·gPd−1·h−1 with liquid-phase selectivities of 63.3 % and 80.0 %, respectively. Meanwhile, green hydrogen derived from water is produced as another valuable product. Combined spectroscopy investigation suggests that the reaction proceeds via π-bonded adsorption of olefins over Pd clusters with hydroxylation by hydroxyl radicals formed by photocatalytic dissociation of water.

Pseudomonas putida as a platform for medium-chain length α,ω-diol production: Opportunities and challenges.

Medium-chain-length α,ω-diols (mcl-diols) play an important role in polymer production, traditionally depending on energy-intensive chemical processes. Microbial cell factories offer an alternative, but conventional strains like Escherichia coli and Saccharomyces cerevisiae face challenges in mcl-diol production due to the toxicity of intermediates such as alcohols and acids. Metabolic engineering and synthetic biology enable the engineering of non-model strains for such purposes with P. putida emerging as a promising microbial platform. This study reviews the advancement in diol production using P. putida and proposes a four-module approach for the sustainable production of diols. Despite progress, challenges persist, and this study discusses current obstacles and future opportunities for leveraging P. putida as a microbial cell factory for mcl-diol production. Furthermore, this study highlights the potential of using P. putida as an efficient chassis for diol synthesis.

Iodine‐modified Pt nanoparticles accelerate the hydrogenative ring‐opening of furfurals to linear alcohols

AbstractThe hydrogenative ring‐opening of furfurals (furfural and 5‐methylfurfural) to linear diols (1,4‐pentanediol and 2,5‐hexanediol) is of great significance for bioderived fine chemical synthesis. Unfortunately, the catalytic activity and selectivity are unsatisfactory because of the interference of various side reactions, such as overhydrogenation to tetrahydrofurans. Herein, the preparation of an iodine (I) modified Pt‐based catalyst with abundant Pt‐I pairs is reported for the first time and shows high catalytic efficiency for linear diol synthesis with a yield of 80%–90% via the hydrogenative ring‐opening route, whereas bare Pt counterpart only shows tetrahydrofuran synthesis via the overhydrogenation route. The catalytic reaction mechanism shows the in‐situ hydrogen spillover‐promoted H−‐Pt‐I‐H+ pairs not only supply hydrogenation sites for the C=O hydrogenation step but also provide Brønsted acidic sites for the ring‐opening step. This work presents a feasible and convenient strategy for bifunctional catalysis with powerful linear diol synthesis over iodine‐modified noble metals.

Preparation of α-MoO3 from H3PMo12O40 precursor: synthesis of 1,2-cyclohexanediol from cyclohexene over α-MoO3-TiO2 catalyst

A series of α-MoO3-TiO2 mixed oxides were prepared by calcining a mixture of the heteropolyacid H3PMo12O40 and TiO2 at temperatures ranging from 350 °C to 600 °C. The mixed oxides thus prepared were characterized and tested for the oxidation of cyclohexene by the oxidizing mixture H2O2/CO2. FTIR and XRD characterizations showed that the Keggin structure of H3PMo12O40 was preserved for calcination temperatures below 400 °C. Above 450 °C, Keggin’s structure collapses. XRD analysis revealed that as the calcination temperature increased, more orthorhombic α-MoO3 was formed. Analysis of the reaction mixture by GC-MS showed that oxidation by the H2O2/CO2 mixture leads to 1,2-cyclohexanediol as the main product and to 2-cyclohexene-1-one and 2-cyclohexene-1-ol as minor products. Oxidation by H2O2/CO2 mixture proved to be more effective than H2O2 alone and CO2 alone. The conversion (69.4%) and the 1,2-cyclohexanediol selectivity (93.2%) obtained over α-MoO3-TiO2 mixed oxides, higher than that obtained with TiO2 monoxide and α-MoO3 monoxide, suggest a synergistic effect between TiO2 and α-MoO3. This efficient and stable catalyst after reuse can be developed for the synthesis of diols.

Recent Advances in the Catalytic Hydroconversion of 5-Hydroxymethylfurfural to Valuable Diols.

Biomass, a globally available resource, is a promising alternative feedstock for fossil fuels, especially considering the current energy crisis and pollution. Biomass-derived diols, such as 2,5-bis(hydroxymethyl)furan, 2,5-bis(hydroxymethyl)-tetrahydrofuran, and 1,6-hexanediol, are a significant class of monomers in the polyester industry. Therefore, the catalytic conversion of biomass to valuable diols has received extensive research attention in the field of biomass conversion and is a crucial factor in determining the development of the polyester industry. 5-Hydroxymethylfurfural (HMF) is an important biomass-derived compound with a C6-furanic framework. The hydroconversion of HMF into diols has the advantages of being simple to operate, inexpensive, environmentally friendly, safe, and reliable. Therefore, in the field of diol synthesis, this method is regarded as a promising approach with significant industrialization potential. This review summarizes recent advances in diol formation, discusses the roles of catalysts in the hydroconversion process, highlights the reaction mechanisms associated with the specificities of each active center, and provides an outlook on the challenges and opportunities associated with the research on biomass-derived diol synthesis.

Metabolic Engineering and Regulation of Diol Biosynthesis from Renewable Biomass in Escherichia coli.

As bulk chemicals, diols have wide applications in many fields, such as clothing, biofuels, food, surfactant and cosmetics. The traditional chemical synthesis of diols consumes numerous non-renewable energy resources and leads to environmental pollution. Green biosynthesis has emerged as an alternative method to produce diols. Escherichia coli as an ideal microbial factory has been engineered to biosynthesize diols from carbon sources. Here, we comprehensively summarized the biosynthetic pathways of diols from renewable biomass in E. coli and discussed the metabolic-engineering strategies that could enhance the production of diols, including the optimization of biosynthetic pathways, improvement of cofactor supplementation, and reprogramming of the metabolic network. We then investigated the dynamic regulation by multiple control modules to balance the growth and production, so as to direct carbon sources for diol production. Finally, we proposed the challenges in the diol-biosynthesis process and suggested some potential methods to improve the diol-producing ability of the host.

Synthesis of diols from jojoba oil via rhodium-catalyzed reductive hydroformylation: a smart way to access biobased polyurethanes

Diol was synthesised from Jojoba oil ester by a recyclable catalytic system and was used for biobased polyurethane synthesis.

Reductive Hydroformylation of Isosorbide Diallyl Ether.

Isosorbide and its functionalized derivatives have numerous applications as bio-sourced building blocks. In this context, the synthesis of diols from isosorbide diallyl ether by hydrohydroxymethylation reaction is of extreme interest. This hydrohydroxymethylation, which consists of carbon-carbon double bonds converting into primary alcohol functions, can be obtained by a hydroformylation reaction followed by a hydrogenation reaction. In this study, reductive hydroformylation was achieved using isosorbide diallyl ether as a substrate in a rhodium/amine catalytic system. The highest yield in bis-primary alcohols obtained was equal to 79%.

Recent Advancements in the Development of Osmium Catalysts for Various Oxidation Reactions: A New Era?

ABSTRACT Symmetric and asymmetric dihydroxylation reactions catalyzed by osmium have emerged as the most efficient route in the one-step synthesis of diols. This is because on an industrial scale 1,2-diols are prepared via a two-step procedure. Still, it is a challenge to prepare and apply osmium catalysts in dihydroxylation catalysis because of their safety and environmental implications; e.g., volatile, highly toxic, product contamination, etc. To date, few efforts were reported to comprehensively overcome these drawbacks with great success by heterogenizing to an insoluble matrix, including diminishment in catalytic performance. Hence, the need for efficacious solid-supported osmium catalysts to subdue these difficulties is a topic of great importance. This mini review provides a concise overview of some of the most encouraging solid-supported osmium catalysts reported over the last few years, which proved to be more efficient under mild conditions as opposed to other immobilized osmium catalytic systems. The summary discusses the latest developments in the synthetic heterogenizing and homogenization strategies, structure analysis and investigation toward symmetric and asymmetric dihydroxylation for diol production. Specific emphasis is focused on their mechanistic considerations, their reusability and improvement in their safety, and environmental implications.

Metathesis reaction from bio-based resources: Synthesis of diols and macrodiols using fatty alcohols, β-citronellol and natural rubber

Diols and macrodiols (hydroxytelechelic compounds) were synthesized via metathesis from fatty alcohols and terpenes derivatives using [(1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene) dichloro (o-isopropoxyphenylmethylene) ruthenium] (second generation Hoveyda-Grubbs catalyst) as catalyst. The unsaturated diols: octadec-9-ene-1,18-diol, icos-10-ene-1,20-diol and 3,10-dimethyl-dodec-6-ene-1,12-diol were obtained with yields of 45–98% using mild conditions reaction, in absence of solvent. In other hand, macrodiols with high yields (>97%) and Fn ≈ 2 were synthetized in one-pot reaction by cross-metathesis degradation from the natural rubber (NR) and the cis-1,4-polybutadiene (PB), using the unprotected free alcohols, 9-decen-1-ol (9de), 10-undecen-1-ol (10un) and β-citronellol (βc), as chain transfer agents (CTA's). The results suggest that 9de, 10un and βc were effective CTA's in such metathesis reactions. The molecular weights were changed in a wide range (297 g/mol to 13,650 g/mol) controlling the rubber/CTA ratio and were in good agreement with their theoretical values.

Highly chemoselective hydrogenation of lactone to diol over efficient copper-based bifunctional nanocatalysts

Owing to the high economic values and broad applications of diols with various alkyl chains, the development of efficient heterogeneous catalysts for the highly chemoselective synthesis of diols is highly desirable. In this work, a range of bifunctional Cux/Mg3-xAlO (x = 0.5, 1, 1.5, 2) nanocatalysts derived from layered double hydroxides (LDHs) precursors were fabricated and evaluated in the selective hydrogenation of lactones to synthesize diols. Systematic structure characterizations indicated the bifunctional catalytic sites containing active Cu nanoparticles with controllable sizes and tunable base sites could be finely constructed in the Cux/Mg3-xAlO catalysts. Intrinsic catalytic activity tests were conducted to reveal the structure-activity relationship in the model reaction of selective hydrogenation of γ-valerolactone (GVL) to produce 1,4-pentanediol (1,4-PeD); it was found that the optimal bifunctional Cu1.5/Mg1.5AlO catalyst exhibited greatly improved catalytic activity and selectivity for this reaction, which surpassed various copper-based reference catalysts; the excellent catalytic performance of Cu1.5/Mg1.5AlO was mainly attributed to the cooperative effect of the well-dispersed active Cu nanoparticles and the appropriate surface base sites nearby. Moreover, the bifunctional Cu1.5/Mg1.5AlO catalyst could be extended to other lactones with different ring sizes. This work provides a low-cost, environmentally benign and atom-economic heterogeneous catalytic system for the highly selective and sustainable synthesis of value-added diols.

Synthesis of Dihydroxyalkynyl and Dihydroxyalkyl Nucleotides as Building Blocks or Precursors for Introduction of Diol or Aldehyde Groups to DNA for Bioconjugations.

(3,4-Dihydroxybut-1-ynyl)uracil, -cytosine and -7-deazaadenine 2'-deoxyribonucleoside triphosphates (dNTPs) were prepared by direct aqueous Sonogashira cross-coupling of halogenated dNTPs with dihydroxybut-1-yne and converted to 3,4-dihydroxybutyl dNTPs through catalytic hydrogenation. Sodium periodate oxidative cleavage of dihydroxybutyl-dUTP gave the desired aliphatic aldehyde-linked dUTP, whereas the oxidative cleavage of the corresponding deazaadenine dNTP gave a cyclic aminal. All dihydroxyalkyl or -alkynyl dNTPs and the formylethyl-dUTP were good substrates for DNA polymerases and were used for synthesis of diol- or aldehyde-linked DNA. The aldehyde linked DNA was used for the labelling or bioconjugations through hydrazone formation or reductive aminations.

Selective control for the laccase-catalyzed synthesis of dimers from 2,6-dimethoxyphenol: Optimization of 3,3’,5,5’-tetramethoxy-biphenyl-4,4’-diol synthesis using factorial design, and evaluation of its antioxidant action in biodiesel

The synthesis of transformed products from 2,6-dimethoxyphenol (2,6-DMP) can be selectively obtained through controlled oxidative coupling in laccase-catalyzed reactions, and the products formed are dependent upon the enzyme source, as well as, upon the reactions conditions applied. The laccase from Botryosphaeria rhodina MAMB-05 was investigated for its ability to catalyze the oxidative transformation of 2,6-DMP. Studies conducted in aqueous medium at pH 3.0 and 6.5, for reaction times of 48, 96 and 144 h, led to the formation of three dimers (I, II, III) via carbon-carbon and carbon-oxygen coupling reactions depending upon the pH and reaction time. Dimer I was identified as 3,3′,5,5′-tetramethoxydiphenylquinone by 13C NMR, while dimer II was identified by 1H NMR as 3,3′,5,5′-tetramethoxybiphenyl-4,4′-diol (TMBP). Dimer III was synthesized at pH 3.0 and was influenced by the reaction time (96h), and is predicted to be formed via carbon-oxygen coupling. The chemical structure of III (4-(2,6-dimethoxy-phenoxy)-2,6-dimethoxyphenol) was identified by ESI-Q-TOF HRMS. TMBP (II) was the only product obtained at pH 6.5 independent of the reaction times. TMBP synthesis at pH 6.5 was optimized by design-matrix using a three-factor Box-Behnken incomplete factorial-design that defined the parameters: 2,6-DMP concentration (2.6–3.4 mmol) laccase activity (1.35–3.38 U) and reaction time (120 h) to give a yield of 11.93 ± 0.49%, which agreed with the mathematical model value of 12%. TMBP was evaluated as an antioxidant to stabilize biodiesel, and showed an efficacy similar to the commercial antioxidant standard, butyl hydroxytoluene, indicating that TMBP could serve as an alternative antioxidant to stabilize biodiesel.

Tertiary Amines as Ligands in a Four‐Step Tandem Reaction of Hydroformylation and Hydrogenation: An Alternative Route to Industrial Diol Monomers

AbstractA highly selective synthesis of diols is presented by simple auto‐tandem catalysis to connect hydroformylation and hydrogenation reactions by a rhodium‐catalyst with tertiary amines as ligands. This system allows the hydroformylation/hydrogenation of non‐conjugated cyclic olefins to selectively provide diols under mild reaction conditions. As a model substrate, the industrially relevant dicyclopentadiene (dcpd) was chosen. With the reaction system [Rh(octanoate)2]2 and triethylamine, diols are produced in a high yields of up to 79 % with full conversion of intermediate aldehyde and no evidence of olefin hydrogenation. The scope of the reaction was evaluated and the optimised reaction conditions were successfully scaled up to a 2 L reactor. Finally, the Rh/amine catalyst complex was recycled by a simple water extraction of the diol‐product.

Metabolic Engineering for the Production of Diols

During recent years, the reduced use of chemical processes to produce commodity chemicals, and their substitution with microbiological alternatives, has been frequently observed. However, because of the low efficiency of these biotechnological synthetic materials, investigations are constantly being performed to increase their productivity by controlling the metabolism of bacterial cells. One solution to this problem would be to modify the environmental conditions of the culture of microorganisms or, alternatively, to control the composition of the culture medium by using additional and important enzymes that serve as cofactors in metabolite production. Such production by microorganisms can be also improved by employing genetic engineering tools, whereby modified bacteria are able to synthesize several-fold more desirable metabolites than can wild-type strains. The biotechnological synthesis of diols such as 1,2-propanediol (1,2-PD), 1,3-propanediol (1,3-PD) and 2,3-butanediol (2,3-BD) by the direct microbial bioconversion of renewable feedstocks, and even from waste materials of biofuel production, has been well described. These diols are widely used in many branches of industry, including the production of chemicals, food products, cosmetics and pharmaceuticals. As the methods used to increase the efficiency of their production are still being investigated, recent developments in the production of 1,2-PD, 1,3-PD and 2,3-BD, with regards to the metabolic engineering of production strains and the optimization of fermentation processes, are reviewed and discussed in this chapter. Keywords: 1,2-Propanediol (1,2-PD); 1,3-Propanediol (1,3-PD); 1,4-Butanediol (1,4-PD); 2,3-Butanediol (2,3-PD); culture conditions; medium composition; metabolic engineering

Osmium on Chelate Resin: Nonvolatile Catalyst for the Synthesis of Diols from Alkenes

Osmium tetraoxide (OsO₄) was immobilized on a commercially available chelate resin DIAION CR11 (CR11) just by simply immersing it in a methanol solution of OsO₄ at room temperature. The resulting purple solid, 5% Os/CR11, indicated no volatility, and effectively catalyzed the oxidation of various alkenes to the corresponding diols.

Synthetic studies of alkaloids containing pyrrolidine and piperidine structural motifs.

Awarding Institute: Goa University (India) Date awarded: December, 2013 Supervisor: Prof. Santosh G. Tilve, HOD Chemistry, Goa University, Goa (India)

Research on Synthesis Technology of Polyester Diol Using Vacuum Melting Method

Using adipic acid, ethylene glycol and diethylene glycol as the main raw material, the polyester diol was prepared by vacuum melting method. The effects of the dosage of catalyst, the stuff molar ratio of diol and diacid, reaction temperature of the esterification reaction and other factors on the synthesis process of polyester diol were investigated. The optimal conditions of the polyester diol synthesis by vacuum melting method were determined as follows: the stuff molar ratio of diol and diacid 1.10:1, the dosage of catalyst 0.20‰ (the mass fraction of total amount of dicarboxylic acid and diols), the esterification reaction temperature 230 oC. Under such conditions, the esterification reaction time is 5.5 h to get qualified polyester polyol. Additionally, the structure characteristics of polyester glycol were studied by infrared spectrometer (FTIR) and thermogravimetric analyzer (TGA).

Synthesis and Characterization of Novel Diol, Diacid and Di‐isocyanate from Oleic Acid

AbstractNovel linear diol 2, diacid 3, and diisocyanate 4 with functional groups located at each end of the chain have been produced from oleic acid via a diester precursor. All the compounds were fully characterized by IR, 1H NMR, 13C NMR and Mass Spectrometry. These unbranched terminally‐functionalized compounds are important monomers for the manufacture of biodegradable thermoplastic polyurethanes and polyesters. The general synthetic scheme should also prove useful for the syntheses of diols, diacids and diisocyanates from any unsaturated fatty acid.

Two alternative routes for 1,2-cyclohexanediol synthesis by means of green processes: Cyclohexene dihydroxylation and catechol hydrogenation

In this paper we compare two different reactions, aimed at the synthesis of 1,2-cyclohexanediol. Specifically: (a) the direct epoxidation and hydrolysis (dihydroxylation) of cyclohexene to trans-1,2-cyclohexanediol, with an aqueous solution of hydrogen peroxide, and (b) the hydrogenation of catechol to a mixture of cis and trans-1,2-cyclohexanediol, in an attempt to establish green protocols for the synthesis of diols. Both reactions, the dihydroxylation of cyclohexene and the hydrogenation of catechol, were carried out without organic solvents. In the former case, an unprecedented 97.4% yield to the glycol was obtained, by selecting proper reaction conditions and using a tungstic acid/phosphoric acid catalyst, in a biphasic system with a phase-transfer agent. In the second approach, a heterogeneous alumina-supported Ru(OH)x catalyst was used, and a 90% yield to the glycol was obtained. A comparison of the two processes allowed to show the lower environmental impact of the catechol hydrogenation route.