Solvents from renewable resources

Imperato G, Konig B, Chiappe C (2007) Ionic green solvents from renewable resources. Eur J Org Chem 2007 1049-1058... 

Ionic green solvents from renewable resources 07EJ01049. 

Imperato, G., B. Konig, and C. Chiappe. 2007. Ionic Green Solvents from Renewable Resources. European Journal of Organic Chemistry 2007 (7) 1049-1058. 

ILs have been extensively reviewed in the last 5 years, with particular focus on their synthesis in the area of green solvents from renewable resources [58,79].This section presents some recent advances in this area, accompanied by selected works to illustrate the direction of the field moves in. 

The use of biosolvents, that is, solvents produced from renewable resources (starch and cellulose26), so that the use of fossil resources can be avoided... 

Solvents such as EtOH and EtOAc are particularly attractive as they are obtainable from renewable resources. Although they can be readily purified, if disposal becomes necessary they are relatively environmentally benign. In contrast, several of their higher boiling counterparts have higher toxicity and can be prone to decomposition when heated to near the boiling point. 

An additional approach to environmentally responsible inks is to source the raw materials from renewable resources. In this approach solvents are based mainly on alkyl lactates and binders such as cellulose or nitrocellulose. ... 

In some cases, green reactions are based on feedstocks derived from renewable resources that produce highly pure compounds. Another green option is the use of supercritical fluids that are more benign substances (e.g., water, carbon dioxide, and light nonhalogenated hydrocarbons) such fluids can be used as solvents for separations or as media for reactions, and can be easily recovered from the product mixture and recycled. We can also include here the use of ionic systems of nonvolatile salts that are molten at ambient temperature, and that act as solvents or even have a dual role (as catalysts and solvents), without the risk of unwanted vapors. These ionic solvents replace the more hazardous, volatile, and expensive organic solvents used traditionally. 

The metal-catalyzed oxidation of carbohydrates with molecular oxygen is a remarkable example of green chemistry because reactants are obtained from renewable resources, processes are conducted under mild conditions with air as oxidizing agent and water as solvent, and reaction products are environmentally benign because of their biodegradability. In addition oxidized carbohydrate derivatives can often be obtained with high selectivity, and the catalysts are recyclable. These catalytic processes are, therefore, potentially very attractive for the preparation of specialties or intermediates employed in the food, cosmetic, pharmaceutical, and chemical industries. 

It is an aliphatic polyester derived from renewable resources, such as com starch, tapioca roots, chips or starch, or sugarcane. Polylactic acid or polylactide (PLA) can withstand temperatures up to 110 °C [69]. PLA is soluble in chlorinated solvents, hot benzene, tetrahydrofuran, and dioxane [70]. It can be processed like other thermoplastics into fiber (for example, using conventional melt spinning processes) and film. Due to the chiral nature of lactic acid, several distinct forms of polylactide exist ... 

Solvents derived from renewable resources are inherently greener than other solvents, if one neglects all other factors. Key solvents of this type include CO2, water, methanol, ethanol, acetic acid, limonene, and fatty acid methyl esters the first two in this list have the greatest availability. 

Both native and regenerated cellulose can be used for the preparation of cellulose aerogels. Cellulose in native form, generally nanofibrillar such as bacterial cellulose and microfibrillated cellulose, has been proposed for the preparation of aerocellulose [77, 266]. Aerogels based on NFC can offer advantages from an environmental point of view, because NFC is obtained from renewable resources and no harmful solvents are required during the processing. 

The depletion of earth s fossil energy resources, accompanied by the strong impact of their use on the environment, particularly in the form of higher CO2 emissions, raises the demand for sustainable, safe, and efficient substitution of hitherto crude oil-derived fuels, chemicals, and chemical building blocks from renewable resources. Besides chemical manufacturing of renewable feedstocks to valuable compounds, biotechnological processes afford more and more opportunities to produce fuels, building blocks, and solvents in a cost-effective way from biomass (Bozell and Petersen, 2010). 

The P(3HB)/PLA blend is one of the most studied blends, which exhibits mechanical properties that are intermediate between the individual components. Although PLA and P(3HB) are biodegradable polymers synthesized from renewable resources, their potential applications are hampered due to their brittleness and the formation of very large spherulities. P(3HB)/PLA blends were studied as early as 1996 to explore their miscibility, crystallisation, morphology, mechanical properties and biodegradation behaviour. P(3HB)/PLA blends with different compositions (100/0, 80/20, 60/40, 40/60, 20/80 and 0/100, wt%) were prepared by casting a film from a common solvent, chloroform, at room temperature. ... 

The example presented here illustrates the fact that supercritical technologies may have huge potential for a variety of chemical processes, although the supercritical solvent as such would not be needed. In light of this example, another current hot topic, biodiesel processing from renewable resources, could presumably also benefit from this technology. 

The promise of large-scale low-cost fermentations from renewable resources, especially corn, has spurred interest in the United States to develop chemical production for large-volume chemicals using bio-based processes. Succinic acid can be converted by hydrogenation to 1,4-butanediol, which has a world market in excess of 500,000 metric tons. Butanediol is used to produce polybutylene terephthalate (PBT) resins that have desirable mechanical and thermal properties and are a high-performance version of polyethylene terephthalate resins (PET). Also, 1,4-butanediol is a precursor of tetrahydrofuran, which can be polymerized to polytetrahydrofuran (PTHF). Gamma butyrolactone (GBL) can also be derived from 1,4-butanediol, and much of GBL is used to manufacture the solvent N-methyl-2-pyrrolidone (Szmant 1989). 

This does not mean we will see a mega-ton return to the old style polymers, such as casein plastics, cellulose nitrate and cellulose acetate. Many of these older polymers have severe deficits. For example, wool is eaten by moths and other insects cotton shrinks and does not hold a crease, unless treated with another polymer cellulose acetate is not solvent resistant, and cellulose nitrate is highly flammable. However, these older polymers come from renewable resources, which are also biodegradable, and this is a virtue in today s throw-away society. This alone should resurrect interest in natural polymers. Additionally, we have learned many vital things in the past century which will enable us to develop new and better polymers from biotechnology - polymers which... 

As an answer to the growing demand for products made from renewable resources and with (modified) starch as a reference in mind, a lot of these starches have been devoted to the chemical modification of inulin [3]. Hydrophobization of inulin, e.g. grafting of alkyl chains on to the inulin backbone and as such obtaining an inulin derivative showing the wanted amphiphilic character, can be done in several ways by esterification, by etherification or by carbamoylation. The reactions are usually performed in solvents like pyridine, dimethylformamide or dimethylsulfoxide, using catalysts like, for example, sodium acetate, potassium carbonate or triethylamine. 

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