New Syntheses with Oils and Fats as Renewable Raw Materials for the Chemical Industry

Industrial biotechnology for the production of bio-based chemicals – a cradle-to-grave perspective

Shifting the resource base for chemical production from fossil feedstocks to renewable raw materials provides exciting possibilities for the use of industrial biotechnology-based process tools. This review gives an indication of the current developments in the transition to bio-based production, with a focus on the production of chemicals, and points out some of the challenges that exist in the large-scale implementation of industrial biotechnology. Furthermore, the importance of evaluating the environmental impact of bio-based products with respect to their entire life cycle is highlighted, demonstrating that the choice of the raw material often turns out to be an important parameter influencing the life cycle performance.

Poly(ether urethane) Networks from Renewable Resources as Candidate Biomaterials: Synthesis and Characterization

A series of poly(ether urethane) networks were synthesized from epoxidized methyl-oleate-based polyether polyol and 1,3-propandiol using l-lysine diisocyanate as a nontoxic coupling agent. Polyurethanes with different hard segment contents were prepared to tune the final properties of the materials. The polyurethanes were fully chemically and physically characterized, including water uptake and in vitro hydrolytic degradation measurements. The weight loss of the polyurethanes was traced, and the changes in the surface morphology with the degradation time were examined by scanning electron microscopy. The experimental results revealed that the hard segment content is the main factor that controls the physical, mechanical, and degradation properties of these polymers. The observed diversity in material properties suggests that these polyurethanes may be useful for a wide range of biomedical polymer applications.

Hydrolase-catalysed synthesis of peroxycarboxylic acids: Biocatalytic promiscuity for practical applications

The enzymatic promiscuity concept involves the possibility that one active site of an enzyme can catalyse several different chemical transformations. A rational understanding of the mechanistic reasons for this catalytic performance could lead to new practical applications. The capability of certain hydrolases to perform the perhydrolysis was described more than a decade ago, and recently its molecular basis has been elucidated. Remarkably, a similarity between perhydrolases (cofactor-free haloperoxidases) and serine hydrolases was found, with both groups of enzymes sharing a common catalytic triad, which suggests an evolution from a common ancestor. On the other hand, several biotechnological applications derived from the capability of hydrolases to catalyse the synthesis of peracids have been reported: the use of hydrolases as bleaching agents via in situ generation of peracids; (self)-epoxidation of unsaturated fatty acids, olefins, or plant oils, via Prileshajev epoxidation; Baeyer-Villiger reactions. In the present review, the molecular basis for this promiscuous hydrolase capability, as well as identified applications are reviewed and described in detail.

Novel Polyurethane Electrical Insulator Coatings Based on Amide-Ester-Ether Polyols Derived from Castor Oil and Re-cycled Poly(ethylene terphthalate)

In order to utilize renewable resource raw materials as well as trying to recycle polymeric materials, three new polyols (PEEA1-3) were prepared. Bottle grade recycled poly(ethylene terphthalate) was subjected to transesterification and an amidation reaction with different molecular weights of poly(ethylene glycol) and diethanol amine. The intermediate hydroxyl-terminated compounds were chain extended via an esterification reaction with adipic acid and the products were reacted with castor oil. Polyurethane networks were prepared through the reaction of PEEA1-3 with librated isocyanate groups of a blocked isocyanate curing agent made from trimethylol propane, toluene diisocyanate and N-methyl aniline. All of the starting materials and final cured films were characterized by conventional methods. The curing condition was optimized via gel content measurements. The crosslink density of the samples was determined via an equilibrium swelling method, using the Flory-Rehner equations. The effects of structural parameters on the physical, electrical, mechanical, and dynamic mechanical properties of the polyurethane coatings were evaluated. Investigation of the results showed that the prepared green coatings have environmental benefits as well as high performance as metal insulator coatings.

Design and development of soft nanomaterials from biobased amphiphiles

Design and development of different forms of soft matter from renewable (biomass) feedstocks is gaining attention in current research. This highlight summarizes our continuing efforts towards the effective utilization of renewable resources for new chemicals, fuels and soft materials, and selected successful stories in that direction. Cashew nut shell liquid, an industrial by-product, was used as a raw material to synthesize aryl glycolipids which upon self-assembly generated an array of soft materials such as lipid nanotubes, twisted/helical nanofibers, low-molecular-weight hydro/organogels and liquid crystals. These soft architectures were fully characterized by using different techniques. In another example, amygdalin, a by-product of the apricot industry, was used to develop novel amphiphiles, which showed unprecedented gelation properties in a wide range of solvents. To take these soft nanomaterials to a second level, we successfully demonstrated the utility of these hydrogels as drug delivery vehicles. Intriguingly, enzyme catalysis was used as a tool to make and break the hydrogels, which apparently triggered controlled drug delivery. We believe these results and this highlight will motivate us and others in the field of biobased materials research, green chemistry and soft material development through self-assembly processes, to design and develop new functional materials from plant/crop-based renewable resources, otherwise underutilized.

Enzyme Catalysis: Tool to Make and Break Amygdalin Hydrogelators from Renewable Resources: A Delivery Model for Hydrophobic Drugs

We report a novel approach for the controlled delivery of an antiinflammatory, chemopreventive drug by an enzyme-triggered drug release mechanism via the degradation of encapsulated hydrogels. The hydro- and organogelators are synthesized in high yields from renewable resources by using regioselective enzyme catalysis, and a known chemopreventive and antiinflammatory drug, i.e., curcumin, is used for the model study. The release of the drug occurred at physiological temperature, and control of the drug release rate is achieved by manipulating the enzyme concentration and/or temperature. The byproducts formed after the gel degradation were characterized and clearly demonstrated the site specificity of degradation of the gelator by enzyme catalysis. The present approach could have applications in developing cost-effective controlled drug delivery vehicles from renewable resources, with a potential impact on pharmaceutical research and molecular design and delivery strategies.

Microwave-assisted synthesis and micellization behavior of soy-based copoly(2-oxazoline)s

Polymers based on renewable resources are promising candidates for replacing common organic polymers, and thus, for reducing oil consumption. In this contribution we report the microwave-assisted synthesis of block and statistical copolymers from 2-ethyl-2-oxazoline and 2-“soy alkyl”-2-oxazoline via a cationic ring-opening polymerization mechanism. The synthesized copolymers were characterized by gel permeation chromatography and ¹H-NMR spectroscopy. The micellization of these amphiphilic copolymers was investigated by dynamic light scattering and atomic force microscopy to examine the effect of hydrophobic block length and monomer distribution on the resulting micellar characteristics.

Lipids as renewable resources: current state of chemical and biotechnological conversion and diversification

Oils and fats are the most important renewable raw materials of the chemical industry. They make available fatty acids in such purity that they may be used for chemical conversions and for the synthesis of chemically pure compounds. Oleic acid (1) from "new sunflower," linoleic acid (2) from soybean, linolenic acid (3) from linseed, erucic acid (4) from rape seed, and ricinoleic acid (5) from castor oil are most important for chemical transformations offering in addition to the carboxy group one or more C-C-double bonds. New plant oils containing fatty acids with new and interesting functionalities such as petroselinic acid (6) from Coriandrum sativum, calendic acid (7) from Calendula officinalis, alpha-eleostearic acid (8) from tung oil, santalbic acid (9) from Santalum album (Linn.), and vernolic acid (10) from Vernonia galamensis are becoming industrially available. The basic oleochemicals are free fatty acids, methyl esters, fatty alcohols, and fatty amines as well as glycerol as a by-product. Their interesting new industrial applications are the usage as environmentally friendly industrial fluids and lubricants, insulating fluid for electric utilities such as transformers and additive to asphalt. Modern methods of synthetic organic chemistry including enzymatic and microbial transformations were applied extensively to fatty compounds for the selective functionalization of the alkyl chain. Syntheses of long-chain diacids, omega-hydroxy fatty acids, and omega-unsaturated fatty acids as base chemicals derived from vegetable oils were developed. Interesting applications were opened by the epoxidation of C-C-double bonds giving the possibility of photochemically initiated cationic curing and access to polyetherpolyols. Enantiomerically pure fatty acids as part of the chiral pool of nature can be used for the synthesis of nonracemic building blocks.

Analysis of fatty acid epoxidation by high performance liquid chromatography coupled with evaporative light scattering detection and mass spectrometry

Conventionally, epoxidation of unsaturated fatty acids has been studied either with titrimetric methods or in a lengthy procedure involving derivatization followed by gas chromatography (GC). We have developed a more rapid and descriptive analysis procedure for the substances using high performance liquid chromatography (HPLC) with evaporative light scattering detection (ELSD). Chemo-enzymatic epoxidation of unsaturated fatty acids (oleic, linoleic and linolenic acid, respectively) has been performed using hydrogen peroxide and immobilized lipase from Candida antarctica (Novozym 435). The fatty acids and their epoxidation products were separated by HPLC on a C-18 reversed-phase column using methanol-water containing 0.05% acetic acid as mobile phase. The method facilitated the simultaneous determination of fatty acids and epoxides differing from each other in the number of epoxide rings, the degree of unsaturation and the position of the epoxide rings and double bonds. An important aspect of the method development was the use of electrospray ionization and tandem mass spectrometry to confirm the structure of the epoxide products. It is suggested that the HPLC method, providing more information about the kind and concentration of fatty acids and their epoxides, represents a powerful complement to the existing methods for monitoring epoxidation processes on fatty acids.

Cross-metathesis of unsaturated natural oils with 2-butene. High conversion and productive catalyst turnovers

The cross-metathesis of synthetic and natural triglycerides containing unsaturated fatty acids with 2-butene can be achieved with high conversion and excellent productive turnovers. These reactions are catalysed by second-generation ruthenium-based olefin metathesis catalysts and can be conducted at -5 degrees C in liquid 2-butene.

Novel halo-oxo-allenic fatty ester derivatives from epoxidized methyl santalbate (methyl trans-11-octadecen-9-ynoate)

Methyl santalbate (methyl trans-11-octadecen-9-ynoate) from Sandal wood seed oil, Santalbum alum) was epoxidized to methyl trans-11,12-epoxy-octadec-9-ynoate (1). Treatment of compound 1 with tetrabutylammonium dihydrogentrifluoride, and boron trifluoride etherate gave the corresponding anti- (2a) (57%) and syn- (2b) (35%) fluorohydrin derivatives, respectively. These reactions were regio- and stereoselective in nature. The structures of the anti- and syn- isomers were confirmed by NMR spectroscopy. Ring opening of the epoxy system of compound 1 with lithium chloride gave the anti-chlorohydrin derivative (3) (89%). Oxidation of either compound 2a or 2b gave the same fluoro-keto acetylenic fatty ester (4) (75%), and compound 3 on chromic acid oxidation yielded the corresponding chloro-keto acetylene (5) (73%). Isomerization of compounds 4 and 5 with potassium carbonate in dichloromethane furnished the requisite fluoro-allenic (6) (63%, methyl 11-fluoro-12-oxo-9,10-octadecadienoate) and chloro-allenic (7) (80%, methyl 11-chloro-12-oxo-9,10-octadecadienoate) C(18) fatty esters. All products were confirmed by a combination of spectrometric and spectroscopic techniques.

Lipid chemistry--a personal view of some developments in the last 60 years

This review tracks some of the changes in fatty acid chemistry that have occurred during the past 60 years. Once disparaged, this topic is now recognised as important in biochemistry and nutrition. Among the significant areas that are addressed are fatty acid oxidation and hydrogenation, fatty acid synthesis, and selected reactions of the carboxyl group and of unsaturated centres. Underlying many of the developments that have occurred have been important advances in lipid analysis and a clearer understanding of reaction mechanism and stereochemistry. Developments in the future will include greater use of enzymes in technological processes and will result from environmental pressures to conduct reactions under milder conditions, use less solvent, and produce less waste.

Sustainable chemistry: starting points and prospects

We review here the concept of sustainable chemistry (SC), which is still in its early development. One important element of SC is commonly defined as chemical research aiming at the optimization of chemical processes and products with respect to energy and material consumption, inherent safety, toxicity, environmental degradability, and so on. An increasing number of assessment systems containing quantitative indicators for these aspects are currently being developed. In addition, however, SC should also address the societal aspect of sustainability. With respect to scientific research, the societal aspect is defined here by two requirements: (1) the assumptions, objectives and implications of chemical research and its technical application should be made more transparent to various societal actors; (2) uncertainty and ignorance should be treated more explicitly in the course of scientific research. Meeting these requirements is necessary in order to lift the division between the allegedly disinterested and non-normative scientific research and the value-laden sphere of societal needs, preferences and decision-making situations. This, in turn, is understood here as a contribution to a more sustainable scientific practice. We illustrate the two elements of SC-optimization of products and processes as well as including the societal aspect-with the examples of environmental chemistry, green chemistry and the environmental assessment of chemical products. While considerable progress has been made in these fields, the societal aspect of SC remains to be recognized more fully in all branches of chemical research. One prerequisite for this is the inclusion of SC into chemical education from the very beginning.