Carbohydrates are the prevailing biomass components available for bio-based production. The most direct way to convert carbohydrates into commodity chemicals is by one-step conversion at maximum theoretical yield, such as by anaerobic fermentation without side product formation. Considering these hypothetical yields and petrochemical prices in Europe in 2010-2014, a ranking of 58 commodity chemicals was made using a simple model with ethanol as a base case. It was concluded that base chemicals such as lower olefi ns and benzene-toluene-xylene (BTX) are too cheap and require too much carbohydrate to be produced competitively compared to bioethanol. However, more oxidized products that require multiple conversion steps in petrochemical production, such as adipic acid, acrylic acid, acrylate esters, and 1,4-butanediol, can be produced competitively from carbohydrates if theoretical yields are approached and if processing is effi cient. Instead of carbohydrate fermentation, hypothetical photochemical production from CO 2 was also considered. Using again a simple model, the same commodity chemicals remained the most attractive ones.

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In this work, we report for the first time on the influence of the quality of reactants and reaction conditions on the production of hydrophobically modified ethoxylated urethanes (HEURs) and selected prepolymers without the use of solvents. We show that the polyol water concentration is detrimental to the progress of the main urethane forming reaction, confirming the necessity of carefully drying the reactants below 1000 ppm to suppress the consumption of diisocyanate toward urea during HEUR synthesis. Increasing the mixing speed (≈30 to 750 rpm), reaction temperature (80−110 °C), and catalyst concentration (0.035−2.1 wt % bismuth carboxylate) can significantly increase the rate of molecular weight buildup, but their effect decreases with time as the bulk viscosity increases and mixing limitations eventually take over, leading to the Weissenberg effect and chain growth termination. Consequently, for the selected formulation, the maximum product molecular weight attained lies in the range of ≈20 000−22 000 g/ mol, irrespective of the specific process conditions applied.

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