**2.2 Furfuryl alcohol**

The production of furfuryl alcohol involves two stages: (1) the pentosan is first hydrolysed to pentoses, e.g. xylose, and (2) cyclohydration of the pentoses into furfuryl alcohol. The reaction is catalysed by acids such as dilute sulfuric or phosphoric acid, and the furfuryl alcohol is recovered by steam distillation and fractionation. Yields are generally between 30 and 50% [32].

Furfuryl alcohol is a solvent used in the refining of lubricating oils [33]. During the production of butadiene, an extractive distillation step is required to remove impurities [34]. Furfuryl alcohol is one of the extractive solvents that have been used for this purpose on a commercial scale, for example, at TransFuran Chemicals, USA. Furfuryl alcohol is also used as a solvent during crystallization of anthracene oils and during the modification of high phenolic molding resins to improve the corrosion resistance of the cured resin [35].

#### **2.3 Glycerol and its derivatives**

Global biodiesel production has increased from 0.78 billion (in 2000) to 32.6 billion liters by 2016 [36]. This has made large quantities of glycerol widely available, since biodiesel production generates 10,000 liters of glycerol for every 100,000

**7**

agents [45].

*2.3.2 Diols*

*Bio-Solvents: Synthesis, Industrial Production and Applications*

liters of fuel produced. This oversupply of glycerol, and its low toxicity, has driven many efforts to increase the portfolio of glycerol applications both directly and indirectly (by using it as a raw material to access value-added products). Because of its sweet taste, it can be used directly as a sweetener in processed foods. It is also used as a thickener and stabilizer for foods containing water and oil. Glycerol functions well as a solvent for processing cosmetics (this is where most glycerol is used)

More recently, glycerol has been used as a sustainable replacement for fossilderived monoethylene glycol in purification of bioethanol by extractive distillation. Using glycerol, up to 99% purity of bioethanol is recovered [38]. Although its high viscosity and boiling point complicate reaction workups, several examples of successful Aza-Michael addition and Suzuki-Miyaura and Mizoroki-Heck reactions in

The conversion of glycerol leads to a variety of other products with solvent properties such as solketal, glycerol formal, glycerol carbonate, glycerol oligomers and polymers, deep eutectic solvents (DESs) as well as diols (**Figure 1**) [37, 40]. Solketal and glycerol formal are the products of acid-catalyzed acetone and formaldehyde reactions with glycerol, respectively [41], and currently solketal is sold commercially under the name Augeo™ SL 191. It is used as a solvent in interiorscenting products and household cleaners [42]. Another route to solketal is by

Solketal is polar and has a very high boiling point (188°C), which makes it useful as a coalescent solvent in paints and inks and in controlled release systems (where gradual release of species like pesticides and drugs is required). It is a good heat transfer fluid and fuel additive, especially in gasoline and biodiesel where it favorably reduces the latter's viscosity [41]. Its high sensitivity to acid has limited its use

The main route for preparing di-, tri-, tetra- and polyglycerol is by direct oligomerization or polymerization of glycerol using acid or base catalysts, such as potassium carbonate or sulfuric acid. The base catalyst is usually more efficient due to its better solubility in glycerol, albeit with poor selectivity [44]. Glycerol oligomers and polymers have hydrophilic heads which makes them useful for surfactant applications. By careful control of their length and branching during syntheses, desirable physiochemical properties can be built into them such that they can be used as lubricants, polymers and solvents. They have also been earmarked as replacement solvents for fossil-derived glycol ethers in paints, inks and cleaning

In addition to methanol, ethanol and propanol [46], the hydrogenolysis of glycerol can lead to formation of ethylene glycol (EG) and propylene glycol (PG, 1,2-propanediol and 1,3-propanediol) (**Figure 1**) [47]. It is worth mentioning that diols can also be obtained from thermochemical conversion of fructose in the presence of homogeneous osmium and ruthenium catalysts [48] and from cellulose using a nickel-tungsten carbide catalyst [49]. Recently, Sappi Ltd. acquired Plaxica's Xylex® technology which they plan to utilize in valorizing the hemicellulose component of their pulp processing waste, in producing, furfural and xylitol [50]. Changchun Dacheng Industrial Group operates a commercial integrated biological and thermochemical process that manufactures EG, PG

and forms part of pharmaceutical formulations to name a few [37].

metal-catalyzed condensation of glycidol with acetone [43].

*DOI: http://dx.doi.org/10.5772/intechopen.86502*

glycerol have been reported [38, 39].

as a solvent for reactions.

*2.3.1 Glycerol oligomers and polymers*

#### *Bio-Solvents: Synthesis, Industrial Production and Applications DOI: http://dx.doi.org/10.5772/intechopen.86502*

*Solvents, Ionic Liquids and Solvent Effects*

**6**

**2.2 Furfuryl alcohol**

*Bio-based solvents derived from glycerol.*

**Figure 2.**

Yields are generally between 30 and 50% [32].

corrosion resistance of the cured resin [35].

**2.3 Glycerol and its derivatives**

The production of furfuryl alcohol involves two stages: (1) the pentosan is first hydrolysed to pentoses, e.g. xylose, and (2) cyclohydration of the pentoses into furfuryl alcohol. The reaction is catalysed by acids such as dilute sulfuric or phosphoric acid, and the furfuryl alcohol is recovered by steam distillation and fractionation.

Furfuryl alcohol is a solvent used in the refining of lubricating oils [33]. During the production of butadiene, an extractive distillation step is required to remove impurities [34]. Furfuryl alcohol is one of the extractive solvents that have been used for this purpose on a commercial scale, for example, at TransFuran Chemicals, USA. Furfuryl alcohol is also used as a solvent during crystallization of anthracene oils and during the modification of high phenolic molding resins to improve the

Global biodiesel production has increased from 0.78 billion (in 2000) to 32.6 billion liters by 2016 [36]. This has made large quantities of glycerol widely available, since biodiesel production generates 10,000 liters of glycerol for every 100,000

liters of fuel produced. This oversupply of glycerol, and its low toxicity, has driven many efforts to increase the portfolio of glycerol applications both directly and indirectly (by using it as a raw material to access value-added products). Because of its sweet taste, it can be used directly as a sweetener in processed foods. It is also used as a thickener and stabilizer for foods containing water and oil. Glycerol functions well as a solvent for processing cosmetics (this is where most glycerol is used) and forms part of pharmaceutical formulations to name a few [37].

More recently, glycerol has been used as a sustainable replacement for fossilderived monoethylene glycol in purification of bioethanol by extractive distillation. Using glycerol, up to 99% purity of bioethanol is recovered [38]. Although its high viscosity and boiling point complicate reaction workups, several examples of successful Aza-Michael addition and Suzuki-Miyaura and Mizoroki-Heck reactions in glycerol have been reported [38, 39].

The conversion of glycerol leads to a variety of other products with solvent properties such as solketal, glycerol formal, glycerol carbonate, glycerol oligomers and polymers, deep eutectic solvents (DESs) as well as diols (**Figure 1**) [37, 40].

Solketal and glycerol formal are the products of acid-catalyzed acetone and formaldehyde reactions with glycerol, respectively [41], and currently solketal is sold commercially under the name Augeo™ SL 191. It is used as a solvent in interiorscenting products and household cleaners [42]. Another route to solketal is by metal-catalyzed condensation of glycidol with acetone [43].

Solketal is polar and has a very high boiling point (188°C), which makes it useful as a coalescent solvent in paints and inks and in controlled release systems (where gradual release of species like pesticides and drugs is required). It is a good heat transfer fluid and fuel additive, especially in gasoline and biodiesel where it favorably reduces the latter's viscosity [41]. Its high sensitivity to acid has limited its use as a solvent for reactions.
