Synthesis, Chemistry and Applications of 5-Hydroxymethyl-furfural And Its Derivatives

The prospect of exciting research activity in the chemistry of furfural derived compounds such as 5-hydroxymethylfurfural (HMF), 2,5-furandicarbaldehyde and 2,5-furan-dicarboxylic acid prompted the writing of this article. As the field of application of these compounds is really enormous, it is no wonder that research in this area, starting at the end of 19th century, is still being developed. Numerous important scientific groups are carrying out studies on the synthesis, and applications of HMF and its derivatives. Notable among these are, Gaset (Toulouse), Descotes (Lyon), Lichtenthaler (Darmstadt), and Gelas (Clermont-Ferrand). Not only academic scientists are interested in this subject, the chemical industry, is represented by sugar companies such as Beghin-Say, and Süddeutsche Zucker. Despite this interest, there are not many comprehensive monographs or reviews covering the chemistry of HMF. Two classic reviews, by Newth and by Feather and Harris, appeared in 1951 and 1973 respectively. Reviews by Gaset et al.,3 Faury et al. and by Kuster are more recent, but they are not detailed. An important review review by Cottier and Descotes6 appeared in 1991. This review is written to update those above, to summarize the contributions of the last 100 years; and to emphasize recent developments especially in electrochemistry, and on dialdehyde and diacid chemistry.HMF is a good starting material for the synthesis of precursors of various pharmaceuticals, thermo-resistant polymers and complex macrocycles. Among these precursors, one can find 2,5- furandicarbaldehyde and 2,5-furandicarboxylic acid; these two compounds are described in detail in this article. The field of their applications is enormous – the dialdehyde offers itself to be the precursor for the synthesis of complexing macrocycles, oxo-porphirines, oxo-annulenes as well as mono- and bis alkenyl and alkynyl furans. The diacid is a building block for numerous polyesters and polyamides; its derivatives were found to be useful in pharmacology. No wonder then, that numerous methods for their preparation have been worked out and published.N/

THE REACTION OF TETRAMETHYLSILANE WITH BORON TRIBROMIDE

The reaction of tetramethylsilane with boron tribromide in deuterochloroform in ambient temperature or at 40°C led to bromotrimethylsilane (3) and to dibromomethylborane (4). Identity of products was confirmed by NMR spectroscopy. Analogical reaction carried out in 1,3-dichloropropane allowed to separate products of the reaction and to obtain them in 68% and 59% yields respectively.CNRS Franc

Addition of Di(trimethylsilyl) Phosphite to Schiff Bases of 2,5-Diformylfuran

A series of 2,5-Furanyl-bis-(aminomethylphosphonic Acids) has been synthesized by the addition of di(trimethylsilyl) phosphite to azomethine bond of achiral Schiff bases derved from 2,5-diformylfuran. The stereochemical aspect of this reaction has been studied and compared with the behaviour of achiral terephthalic Schiff bases in similar reaction. Whereas, addition to achiral terephthalic Schiff bases was found to be highly stereoselective, the analogous reaction with achiral 2,5-diformylfuran Schiff bases was stereoselective exclusively in the case when the substituent is benzyl.N/

Injury and recovery rates of the aging athlete

The precise rates of injury and recovery of the Masters athlete are not yet well known. Considering that older athletes are participating at greater rates now than ever before, and that these athletes are routinely setting age-specific records, there is greater incentive to illustrate the responses related to exercise and competition as it pertains to injury and recovery. The majority of the literature focuses on younger athletes, which may be due to the amount of attention this group of individual’s commands because of their physical capabilities and performance figures, but also due to their greater incidence of acute injury such as catastrophic failure of ligaments in the knee. This literature review therefore aims to elucidate some of the factors that may contribute to an older athletes seemingly different propensity for overuse injuries, as well as uncovering the precise rates of acute and chronic injury that the Masters athlete suffers.Kinesiology and Health Educatio

Central circulatory hemodynamics as a function of gravitational stress

This study focuses on an evaluation of the central hemodynamics in a nonhuman primate model to variations in gravitational states. The baboon, phylogenectically close to man, was chosen as the human surrogate. The study environments selected are head-down and head-up tilt in the physiology laboratory, centrifugation to test hypergravic stress, and parabolic flights to test transient acute responses to microgravity

Exposure to noise and ototoxic chemicals in the Australian workforce

Objective: To determine the current prevalence of exposure to workplace noise and ototoxic chemicals, including co-exposures. Method: A cross-sectional telephone survey of nearly 5000 Australian workers was conducted using the web-based application, OccIDEAS. Participants were asked about workplace tasks they performed and predefined algorithms automatically assessed worker's likelihood of exposure to 10 known ototoxic chemicals as well as estimated their full shift noise exposure level (LAeq,8h) of their most recent working day. Results were extrapolated to represent the Australian working population using a raked weighting technique. Results: In the Australian workforce, 19.5% of men and 2.8% of women exceeded the recommended full shift noise limit of 85 dBA during their last working day. Men were more likely to be exposed to noise if they were younger, had trade qualifications and did not live in a major city. Men were more likely exposed to workplace ototoxic chemicals (57.3%) than women (25.3%). Over 80% of workers who exceeded the full shift noise limit were also exposed to at least one ototoxic chemical in their workplace. Conclusion: The results demonstrate that exposures to hazardous noise and ototoxic chemicals are widespread in Australian workplaces and co-exposure is common. Occupational exposure occurs predominantly for men and could explain some of the discrepancies in hearing loss prevalence between genders

Towards the conversion of carbohydrate biomass feedstocks to biofuels via hydroxylmethylfurfural

This review appraises the chemical conversion processes recently reported for the production of hydroxylmethylfurfural (HMF), a key biorefining intermediate, from carbohydrate biomass feedstocks. Catalytic sites or groups required for the efficient and selective conversion of hexose substrates to HMF are examined. The principle of concerted catalysis was used to rationalise the dehydration of fructose and glucose to HMF in non-aqueous media. A survey of reported reaction routes to diesel-range biofuel intermediates from HMF or furfural is presented and self-condensation reaction routes for linking two or more HMF and furfural units together toward obtaining kerosene and diesel-range biofuel intermediates are highlighted. The reaction routes include: benzoin condensation, condensation of furfuryl alcohols, hetero Diels–Alder reaction and ketonisation reaction. These reaction routes are yet to be exploited despite their potential for obtaining kerosene and diesel-range biofuel intermediates exclusively from furfural or hydroxylmethylfurfural

Supported ionic liquid silica nanoparticles (SILnPs) as an efficient and recyclable heterogeneous catalyst for the dehydration of fructose to 5-hydroxymethylfurfural

Supported ionic liquid nanoparticles (SILnPs) having particle size ranging from 293 ± 2 to 610 ± 11 nm have been prepared by immobilization of ionic liquid, 1-(tri-ethoxy silyl-propyl)- 3-methyl-imidazolium hydrogen sulfate (IL-HSO4) on the surface of silica nanoparticles. The catalytic activity of the prepared SILnPs was investigated for the dehydration of fructose to 5-hydroxymethylfurfural (HMF) in the presence of dimethylsulfoxide (DMSO) as a solvent. The reaction temperature and amount of catalyst have been optimized for dehydration of fructose over SILnPs using experimental design leading to 99.9% fructose conversion and 63.0% HMF yield using silica SILnPs (d = 610 ± 11) nm at 130.0 ◦C in 30 min reaction time. The SILnPs catalysts developed in this study present improved performances over other zeolites and strong acid ion exchange resin catalysts, and they have been efficiently and very easily recycled over seven times without any significant loss in fructose conversion and HMF yield