Chemical Building Blocks Research Articles

Screening of sorbents for recovery of succinic and itaconic acid from fermentation broths

AbstractBACKGROUNDThe di‐carboxylic acids succinic acid and itaconic acid are promising building block chemicals that can be produced through fermentation, but the processes would benefit from enhancements in product recovery. While sorption has already been studied to some extent for succinate/succinic acid removal, literature on the potential of sorption for itaconic acid recovery is scarce. This work aimed to screen a range of sorbents and/or resins for their capacity to separate both acids from fermentation broths, envisaging both ex situ and in situ product recovery applications.RESULTSStatic batch screening led to a shortlist of four promising products. These were further characterized in terms of dynamic sorption capacity, regenerability, acid recovery, ability to concentrate the product and stability during sorption–desorption cycles. Final tests with real fermentation broth gave unsatisfactory results for succinic acid recovery. For itaconic acid, promising results were obtained both on synthetic solutions and on a real fermentation broth.CONCLUSIONWhile it is doubtful that adsorption will be the process of choice for in situ or ex situ succinic acid recovery, well performing sorbents could be identified for itaconic acid recovery from fermentation broths, offering perspectives for in situ product recovery applications. © 2017 Society of Chemical Industry

Propionic acid production from corn stover hydrolysate by Propionibacterium acidipropionici

BackgroundThe production of value-added chemicals alongside biofuels from lignocellulosic hydrolysates is critical for developing economically viable biorefineries. Here, the production of propionic acid (PA), a potential building block for C3-based chemicals, from corn stover hydrolysate is investigated using the native PA-producing bacterium Propionibacterium acidipropionici.ResultsA wide range of culture conditions and process parameters were examined and experimentally optimized to maximize titer, rate, and yield of PA. The effect of gas sparging during fermentation was first examined, and N2 was found to exhibit improved performance over CO2. Subsequently, the effects of different hydrolysate concentrations, nitrogen sources, and neutralization agents were investigated. One of the best combinations found during batch experiments used yeast extract (YE) as the primary nitrogen source and NH4OH for pH control. This combination enabled PA titers of 30.8 g/L with a productivity of 0.40 g/L h from 76.8 g/L biomass sugars, while successfully minimizing lactic acid production. Due to the economic significance of downstream separations, increasing titers using fed-batch fermentation was examined by changing both feeding media and strategy. Continuous feeding of hydrolysate was found to be superior to pulsed feeding and combined with high YE concentrations increased PA titers to 62.7 g/L and improved the simultaneous utilization of different biomass sugars. Additionally, applying high YE supplementation maintains the lactic acid concentration below 4 g/L for the duration of the fermentation. Finally, with the aim of increasing productivity, high cell density fed-batch fermentations were conducted. PA titers increased to 64.7 g/L with a productivity of 2.35 g/L h for the batch stage and 0.77 g/L h for the overall process.ConclusionThese results highlight the importance of media and fermentation strategy to improve PA production. Overall, this work demonstrates the feasibility of producing PA from corn stover hydrolysate.

Production of fumaric acid by immobilized Rhizopus arrhizus RH 7-13-9# on loofah fiber in a stirred-tank reactor

Fumaric acid is an important building-block chemical. The production of fumaric acid by fermentation is possible. Loofah fiber is a natural, biodegradable, renewable polymer material with highly sophisticated and pore structure. This work investigated a new immobilization method using loofah fiber as carrier to produce fumaric acid in a stirred-tank reactor. Compared with other carriers, loofah fiber was proven to be efficiently and successfully used in the reactor. After the optimization process, 20g addition of loofah fiber and 400rpm agitation speed were chosen as the most suitable process conditions. 30.3g/L fumaric acid in the broth as well as 19.16g fumaric acid in the precipitation of solid was achieved, while the yield from glucose reached 0.211g/g. Three batches of fermentation using the same loofah fiber carrier were conducted successfully, which meant it provided a new method to produce fumaric acid in a stirred-tank reactor.

Concentrated HCl Catalyzed 5-(Chloromethyl)furfural Production from Corn Stover of Varying Particle Sizes

5-(Chloromethyl) Furfural (CMF) is a potential chemical building block for replacing petroleum-derived chemicals derived from lignocellulosic feedstocks. In this study, hand harvested corn stover and mechanically forage chopped corn stover was processed in a 1 L hydrolysis reactor to produce CMF in a biphasic, two solvent system. Both 1,2 dichloroethane (DCE) and dichloromethane (DCM) were tested as organic solvents. The results showed that DCE performed better than DCM due to temperature and pressure limitations of the reactor system. Using DCE as the extracting solvent, the effects of solids loading, particle size, and moisture content of the corn stover on the hydrolysis efficiency were determined. One liter acid hydrolysis reactor provides consistent and reproducible yields of 63% CMF from hand harvested corn stover as feedstock at solid loading of 10% wt/v, 100C for 1 h. For the forage chopped corn stover, increasing particle size brings an increase in the feedstock sugar content. Foraged chopped corn stover (FCCS) particle sizes larger than 19 mm (0.75 in.) results in significant reduction in CMF yield from 43 to 35%.

The Narrow Road to the Deep Past: In Search of the Chemistry of the Origin of Life.

The sequence of events that gave rise to the first life on our planet took place in the Earth's deep past, seemingly forever beyond our reach. Perhaps for that very reason the idea of reconstructing our ancient story is tantalizing, almost irresistible. Understanding the processes that led to synthesis of the chemical building blocks of biology and the ways in which these molecules self-assembled into cells that could grow, divide and evolve, nurtured by a rich and complex environment, seems at times insurmountably difficult. And yet, to my own surprise, simple experiments have revealed robust processes that could have driven the growth and division of primitive cell membranes. The nonenzymatic replication of RNA is more complicated and less well understood, but here too significant progress has come from surprising developments. Even our efforts to combine replicating compartments and genetic materials into a full protocell model have moved forward in unexpected ways. Fortunately, many challenges remain before we will be close to a full understanding of the origin of life, so the future of research in this field is brighter than ever!

Awakening sleeping beauty: production of propionic acid in Escherichia coli through the sbm operon requires the activity of a methylmalonyl-CoA epimerase

BackgroundPropionic acid is used primarily as a food preservative with smaller applications as a chemical building block for the production of many products including fabrics, cosmetics, drugs, and plastics. Biological production using propionibacteria would be competitive against chemical production through hydrocarboxylation of ethylene if native producers could be engineered to reach near-theoretical yield and good productivity. Unfortunately, engineering propionibacteria has proven very challenging. It has been suggested that activation of the sleeping beauty operon in Escherichia coli is sufficient to achieve propionic acid production. Optimising E. coli production should be much easier than engineering propionibacteria if tolerance issues can be addressed.ResultsPropionic acid is produced in E. coli via the sleeping beauty mutase operon under anaerobic conditions in rich medium via amino acid degradation. We observed that the sbm operon enhances amino acids degradation to propionic acid and allows E. coli to degrade isoleucine. However, we show here that the operon lacks an epimerase reaction that enables propionic acid production in minimal medium containing glucose as the sole carbon source. Production from glucose can be restored by engineering the system with a methylmalonyl-CoA epimerase from Propionibacterium acidipropionici (0.23 ± 0.02 mM). 1-Propanol production was also detected from the promiscuous activity of the native alcohol dehydrogenase (AdhE). We also show that aerobic conditions are favourable for propionic acid production. Finally, we increase titre 65 times using a combination of promoter engineering and process optimisation.ConclusionsThe native sbm operon encodes an incomplete pathway. Production of propionic acid from glucose as sole carbon source is possible when the pathway is complemented with a methylmalonyl-CoA epimerase. Although propionic acid via the restored succinate dissimilation pathway is considered a fermentative process, the engineered pathway was shown to be functional under anaerobic and aerobic conditions.

Quantitative NMR Approach to Optimize the Formation of Chemical Building Blocks from Abundant Carbohydrates.

The future role of biomass-derived chemicals relies on the formation of diverse functional monomers in high yields from carbohydrates. Recently, it has become clear that a series of α-hydroxy acids, esters, and lactones can be formed from carbohydrates in alcohol and water solvents using tin-containing catalysts such as Sn-Beta. These compounds are potential building blocks for polyesters bearing additional olefin and alcohol functionalities. An NMR approach was used to identify, quantify, and optimize the formation of these building blocks in the Sn-Beta-catalyzed transformation of abundant carbohydrates. Record yields of the target molecules can be achieved by obstructing competing reactions through solvent selection.

Demonstrating Large Scale Industrial CCS through CCU – A Case Study for Methanol Production

Methanol is a basic chemical building block used in producing other commodities that we used in our daily lives. In the last decade, due to regulation and policy framework in the transport sector, there is also a significant growth in the use of methanol as fuel (i.e. additives to gasoline, production of MTBE, bio-diesel, synthetic gasoline, etc…).Methanol is produced by reacting CO and CO2 with H2. Traditionally, this is produced in a two-steps process – i.e. syngas production and methanol synthesis. Most of the CO2 is emitted at the syngas production side of the operation. The question arises if CO2 is captured, what is its potential for the CO2 to be used in the methanol synthesis? What is the limitation of CCU on-site? How could this support the deployment and economics of industrial CCS?This paper aims to present:•Techno-economic evaluation of deploying CO2 capture in a mega-methanol plant using NG as feedstock. This plant include a combine reforming process (SMR-ATR configuration) to produce the syngas; methanol synloop and methanol purification unit producing AA grade methanol.•Concept of on-site CCU as a possible route to expand future methanol production capacity and at the same time promote the deployment of industrial CCS.

Microbial production of organic acids by endophytic fungi

Abstract The microbial production of organic acids has been considered as a promising strategy to obtain building-block chemicals from renewable feedstocks such as lignocellulosic agro-industrial wastes. This approach is in accordance with the biorefinery concept where the production of biofuels is integrated to higher-value platform chemicals. However, finding a suitable microbial source and the optimum cultivation conditions remains a challenge for the implementation of such process. Endophytic microorganisms have been explored as a source of novel biochemical compounds for biotechnological applications, but the production of organic acids by endophytic fungi remains to be investigated. Here, the potential of using endophytic fungi for organic acids production has been evaluated by carrying out a screening of 35 fungal strains isolated from the leaves and branches of trees inhabiting two mangroves in the state of Sao Paulo, Brazil. The cultivation of a selected Aspergillus awamori 09 (4) strain under solid-state fermentation (SSF) using a mix of wheat bran and sugarcane bagasse (1:3) resulted in 135.5 mg/g of organic acids, which represents around 7-fold increase when compared to the use of sugarcane bagasse alone. These results indicate the potential of mangrove-associated endophytic fungi for organic acid production under SSF using agro-industrial wastes as feedstock, being compatible with the current bioeconomy demands.

Safer, greener route to methyl nitroacetate

Methyl nitroacetate is a handy chemical building block. It can be used to produce α-amino acids, isoxazoles, and α,β-unsaturated compounds. It’s also a useful reactant in Michael additions, Mannich reactions, and cyclopropanations. But it’s expensive. One gram costs anywhere from $22 to $115, depending on the vendor. That’s probably because the process that has been used to make methyl nitroacetate for more than 40 years is dangerous. The 1976 procedure published in Organic Syntheses (DOI: 10.15227/orgsyn.055.0077) requires one to dry the highly explosive intermediate dipotassium salt of nitroacetic acid in a vacuum desiccator and then grind it with a mortar and pestle. The protocol also uses carcinogenic benzene as an extraction solvent and requires two distillations. Now, Pablo E. Guzmán, Jesse J. Sabatini, and coworkers at the U.S. Army Research Laboratory have developed a safer, more environmentally friendly way to make this ester (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00093).

Covestro pursues biobased aniline

In a development that could eventually put a large swath of the polymers world on a low-carbon footing, Bayer spin-off Covestro has demonstrated in the lab a process for making the polyurethane precursor aniline from sugar instead of petrochemical raw materials. Aniline is one of the most important chemical building blocks. Nearly 5 million metric tons of it is used globally, mostly to make the polyurethane raw material methylene diphenyl diisocyanate. Aniline is also used to manufacture dyes, pigments, rubber processing chemicals, and agricultural chemicals. In the conventional route to aniline, benzene is nitrated with nitric acid and then hydrogenated into aniline. Historically, aniline has also been made by reacting phenol and ammonia. Covestro hasn’t completely taken the wraps off its process. The company tells C&EN that a microorganism combines sugar and ammonia into an unnamed intermediate. A chemical catalyst then converts this molecule into aniline, resulting in a product

Itaconic acid used as a versatile building block for the synthesis of renewable resource‐based resins and polyesters for future prospective: a review

AbstractItaconic acid, a carbohydrate‐derived aliphatic dicarboxylic acid, is a potential chemical for the synthesis of renewable resource‐based resins and polyesters. Owing to environmental reasons, there is a gradual demand for renewable resources in the chemical industry. Conversely, as a rather underappreciated side effect of this growth, novel chemical building blocks are obtained, which are not commercially derived from petrochemical sources. In this respect, itaconic acid has attracted much attention and its trifunctional structure leads to the synthesis of novel polymeric materials. This review discusses the most relevant information for bio‐based resins and polyesters resulting from itaconic acid and distinctive properties for various commercial applications. © 2017 Society of Chemical Industry

Biosuccinic Acid from Lignocellulosic-Based Hexoses and Pentoses by Actinobacillus succinogenes: Characterization of the Conversion Process.

Succinic acid (SA) is a well-established chemical building block. Actinobacillus succinogenes fermentation is by far the most investigated route due to very promising high SA yield and titer on several sugars. This study contributes to include the SA production within the concept of biorefinery of lignocellulose biomass. The study was focused on the SA production by A. succinogenes DSM 22257 using sugars representative from lignocellulose hydrolysis-glucose, mannose, arabinose, and xylose-as carbon source. Single sugar batch fermentation tests and mixture sugar fermentation tests were carried out. All the sugars investigated were converted in succinic acid by A. succinogenes. The best fermentation performances were measured in tests with glucose as carbon source. The bacterial growth kinetics was characterized by glucose inhibition. No inhibition phenomena were observed with the other sugar investigated. The sugar mixture fermentation tests highlighted the synergic effects of the co-presence of the four sugars. Under the operating conditions tested, the final concentration of succinic acid in the sugar mixture test was larger (27g/L) than that expected (25.5g/L) by combining the fermentation of the single sugar. Moreover, the concentration of acetic and formic acid was lower, consequently obtaining an increment in the succinic acid specificity.

Ultrasound-assisted acid hydrolysis of cellulose to chemical building blocks: Application to furfural synthesis

In this work, the use of ultrasound energy for the production of furanic platforms from cellulose was investigated and the synthesis of furfural was demonstrated. Several systems were evaluated, as ultrasound bath, cup horn and probe, in order to investigate microcrystalline cellulose conversion using simply a diluted acid solution and ultrasound. Several acid mixtures were evaluated for hydrolysis, as diluted solutions of HNO3, H2SO4, HCl and H2C2O4. The influence of the following parameters in the ultrasound-assisted acid hydrolysis (UAAH) were studied: sonication temperature (30 to 70°C) and ultrasound amplitude (30 to 70% for a cup horn system) for 4 to 8molL−1 HNO3 solutions. For each evaluated condition, the products were identified by ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-ToF-MS), which provide accurate information regarding the products obtained from biomass conversion. The furfural structure was confirmed by nuclear magnetic resonance (1H and 13C NMR) spectroscopy. In addition, cellulosic residues from hydrolysis reaction were characterized using scanning electron microscopy (SEM), which contributed for a better understanding of physical-chemical effects caused by ultrasound. After process optimization, a 4molL−1 HNO3 solution, sonicated for 60min at 30°C in a cup horn system at 50% of amplitude, lead to 78% of conversion to furfural. This mild temperature condition combined to the use of a diluted acid solution represents an important contribution for the selective production of chemical building blocks using ultrasound energy.

Photoelectroreduction of Building-Block Chemicals.

Conventional photoelectrochemical cells utilize solar energy to drive the chemical conversion of water or CO2 into useful chemical fuels. Such processes are confronted with general challenges, including the low intrinsic activities and inconvenient storage and transportation of their gaseous products. A photoelectrochemical approach is proposed to drive the reductive production of industrial building-block chemicals and demonstrate that succinic acid and glyoxylic acid can be readily synthesized on Si nanowire array photocathodes free of any cocatalyst and at room temperature. These photocathodes exhibit a positive onset potential, large saturation photocurrent density, high reaction selectivity, and excellent operation durability. They capitalize on the large photovoltage generated from the semiconductor/electrolyte junction to partially offset the required external bias, and thereby make this photoelectrosynthetic approach significantly more sustainable compared to traditional electrosynthesis.

Decarboxylative alkenylation.

Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, plays an essential role in the foundation of how organic matter is manipulated.1 Despite its importance, olefin synthesis still largely relies upon chemistry invented more than three decades ago, with metathesis2 being the most recent addition. Here we describe a simple method to access olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids. The same activating principles used in amide-bond synthesis can thus be employed, under Ni- or Fe-based catalysis, to extract CO2 from a carboxylic acid and economically replace it with an organozinc-derived olefin on mole scale. Over sixty olefins across a range of substrate classes are prepared, and the ability to simplify retrosynthetic analysis is exemplified with the preparation of sixteen different natural products across a range of ten different families.

Electrochemical Energy Storage of Ni-Doped Metal Organic Framework and Reduced Graphene Oxide Composites

Metal Organic Frameworks (MOFs) are crystalline, open-porous materials consisting of metal ions or metal-oxo units coordinated by electron donating organic ligands and possess very high surface area, well defined pore sizes, tailorable structure and permeability to guest molecules. MOFs have been widely used in catalysis, gas separation, drug storage and delivery, imaging and sensing, optoelectronics and molecular sieving. Although these chemical building blocks can participate in electron exchange processes with the likelihood of providing rich fundamental data; utilizing these materials for energy storage application have been limited. In the present study, composites of a Ni-doped MOF with reduced graphene Oxide (rGO) are synthesized in bulk (gram scale) quantities. The composites are composed of rGO sheets which avoid restacking from the physical presence of MOF crystals. Ni in Ni-doped MOF is found to engage in a reversible, efficient, redox reaction shuttling between Ni and Ni(OH)2 in aqueous potassium hydroxide (KOH) electrolyte. Employing electrochemical impedance spectroscopy, we determined the charge transfer resistance to be 184 mΩ for MOF, 74 mΩ for a Ni doped MOF and 6 mΩ for an rGO-Ni-doped MOF composite, but these modifications do not affect the mass transfer resistance. This redox reaction in conjunction with the lowered charge transfer resistance from the introduction of rGO underpin the synergy which dramatically increases the capacitance to 758 F/g in the rGO-Ni-doped MOF composite, when the parent MOF could store only 100 F/g and a physical composite of rGO and Ni-doped MOF could algebraically achieve about 240 F/g. A generic approach of doping MOFs with a redox active metal and forming a composite with rGO transforms an electro-inactive MOF to high capacity energy storage material with energy density of 37.8 Wh/kg at a power density of 227 W/kg. These results can promote the development of high performance energy storage materials from the wide family of MOFs available.

Mechanistic Insight into the Electrocatalytic Hydrogenation and Electroreduction of Furfural

Electrochemical reduction of biomass-derived platform chemicals is an emerging route for biofuels and chemicals production, where renewable electricity drives reactions on electrodes without the need for external hydrogen supply.1-3 However, the mechanisms governing electrochemical reduction of biomass-derived furanic compounds and its competition with hydrogen evolution reaction (HER) remain unclear. In this talk, we investigate the electrochemical reduction of furfural on copper electrodes for the production of 2-methylfuran (an important potential biofuel additive), furfuryl alcohol (a valuable chemical building block), and dimerization products. Through novel electrochemical techniques, we distinguish between two mechanisms – electrocatalytic hydrogenation (ECH) and outer-sphere electroreduction (ER). Understanding of the underlying mechanisms enables us to tune product selectivity and the competition between ECH, ER, and HER by varying reaction conditions including cathode potential, initial furfural concentration and electrolyte pH. Cyclic voltammetry and bulk electrolysis results clarify the reaction pathways of 2-methylfuran and furfuryl alcohol formation under these conditions. We demonstrate that electrochemical reduction is a promising route for selective furfural conversion and highlight the importance of the underlying mechanisms. These findings can be applied to related biomass-derived platform chemicals including 5-(hydroxymethyl)furfural and other carbonyl-containing compounds.

Purification of Polymer-Grade Fumaric Acid from Fermented Spent Sulfite Liquor

Fumaric acid is a chemical building block with many applications, namely in the polymer industry. The fermentative production of fumaric acid from renewable feedstock is a promising and sustainable alternative to petroleum-based chemical synthesis. The use of existing industrial side-streams as raw-materials within biorefineries potentially enables production costs competitive against current chemical processes, while preventing the use of refined sugars competing with food and feed uses and avoiding purposely grown crops requiring large areas of arable land. However, most industrial side streams contain a diversity of molecules that will add complexity to the purification of fumaric acid from the fermentation broth. A process for the recovery and purification of fumaric acid from a complex fermentation medium containing spent sulfite liquor (SSL) as a carbon source was developed and is herein described. A simple two-stage precipitation procedure, involving separation unit operations, pH and temperature manipulation and polishing through the removal of contaminants with activated carbon, allowed for the recovery of fumaric acid with 68.3% recovery yield with specifications meeting the requirements of the polymer industry. Further, process integration opportunities were implemented that allowed minimizing the generation of waste streams containing fumaric acid, which enabled increasing the yield to 81.4% while keeping the product specifications.

In vitro metabolic engineering for the production of α-ketoglutarate

α-Ketoglutarate (aKG) represents a central intermediate of cell metabolism. It is used for medical treatments and as a chemical building block. Enzymatic cascade reactions have the potential to sustainably synthesize this natural product. Here we report a systems biocatalysis approach for an in vitro reaction set-up to produce aKG from glucuronate using the oxidative pathway of uronic acids. Because of two dehydrations, a decarboxylation, and reaction conditions favoring oxidation, the pathway is driven thermodynamically towards complete product formation. The five enzymes (including one for cofactor recycling) were first investigated individually to define optimal reaction conditions for the cascade reaction. Then, the kinetic parameters were determined under these conditions and the inhibitory effects of substrate, intermediates, and product were evaluated. As cofactor supply is critical for the cascade reaction, various set-ups were tested: increasing concentrations of the recycling enzyme, different initial NAD+ concentrations, as well as the use of a bubble reactor for faster oxygen diffusion. Finally, we were able to convert 10gL−1 glucuronate with 92% yield of aKG within 5h. The maximum productivity of 2.8gL−1 h−1 is the second highest reported in the biotechnological synthesis of aKG.