Lipase-Mediated Syntheses of Trimethylolpropane-Based Biolubricant and Cyclic Carbonate
Abstract: Popular Abstract in English Popular Summary Since the beginning of mankind, humans have managed to find ways to make use of the resources available at hand in order to survive and even to improve their livelihoods. The basic needs for food as well as other amenities were met from plant- and animal resources until the 19th century when industrial revolution changed the base of production to fossil sources. Access to coal initially followed by mineral oil and natural gas accompanied by ingenious chemistry and process development has provided us with unlimited number of products that are present in everything we use today. It has changed the way we live to an extent that it is difficult to think of a life without these products. All the development has of course come at a cost - to the environment and health, the effects of which have started to be felt in terms of increased greenhouse gas emissions, toxic discharges to wastewaters, oceans, persistent pollutants in soil and ground water, climate change, etc. Moreover, the fossil reserves that have taken millions of years to build up, are depleting rapidly. This has led to an increased awareness and demand for alternative renewable resources, toxic-free, environment-friendly production process and nontoxic, biodegradable products. This has provided an interesting challenge to the scientists and engineers to consider the possibilities of developing new or improved products that fulfill the market demand and innovative technologies for processing a different raw material and not posing an environmental burden. Among the several alternatives, industrial biotechnology using microorganisms and their enzymes has gained increased attention for production of chemicals, materials and energy. The studies in this thesis are targeting two product groups that reflect many of the problems stated above - lubricants and polymers (polyurethanes and polycarbonates). Lubricants are used in all mechanical equipment to reduce friction and wear and for other applications. Historically - from the time the Egyptians built pyramids - lubricants were made of vegetable oils and fats, but the modern lubricants are based on mineral oil. Spillage of the lubricants has resulted in widespread environmental problem. For the vegetable oils to work as well as the mineral oil based lubricants, they need to be modified so that the resulting product can be used without problems at very low and very high temperatures. This is possible by reacting fatty acid component of the oil with a branched molecule to give a biolubricant product that is still flowing at sub-zero temperature and is stable above in hot environments. Polyurethanes and polycarbonates are materials with a market of several Mtonnes. They are used for making many products like coatings, foams, adhesives, transparent plastics, etc. The problem however is the use of phosgene, a toxic gas or isocyanate, a product of phosgene, in their manufacture. Even the products may have some traces of the components left in them. Thus, a phosgene/isocyanate-free route for producing these materials would be extremely attractive. One route is to use cyclic carbonates as building blocks that is discussed in this thesis. The thesis presents the use of lipase, an enzyme that breaks down fats and oils in nature, for synthesis of biolubricants and cyclic carbonates. The processes developed do not make use of any volatile organic solvents and are run under very mild conditions compared to the chemical processes. It is shown that different approaches can be used to improve the process efficiency and to get high product yields.
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