Demethylation of 6-(2,4-dimethoxybenzoyl)chromen-2-one and some other aryl methyl ethers was achieved with pyridinium bromide as demethylating agent and sulfolane as solvent. Compared with other demethylation methods, this combination offers advantages of clean conversion, excellent yields, easy operation and workup, and manageable reaction temperatures. This process could be particularly useful for large-scale production because it avoids use of corrosive or moisture-sensitive reagents.

Calcium-based stabilizing materials (CBSMs) such as lime and fly ash are extensively used in subgrade primarily to enhance mechanical strength and improve resistance to chemical attack, resulting in more durable roadway. The soluble sulfate phase contained in some soils, however, can react with CBSMs and form ettringite minerals. If the soil is compacted before the end of this reaction, large, unstable, and volumetric swelling can occur. Among several methods to control sulfate-induced swelling, a “mellowing” approach is typically used because of its efficient, economical, and practical benefits when dealing with calcium-based stabilization of soils with significant soluble sulfate contents. Although the mellowing method is one of the frequently used methods, little data is available on the characterization of the specified mellowing process in the high-sulfate-bearing soil during the mellowing period. A research program investigated key factors influencing the mellowing process during the mellowing period, explaining how stabilizer type and content, remixing interval, mellowing period, and temperature play a role in reducing soluble sulfate content. Moreover, for selected mixtures, the 3-dimensional volumetric expansion and retained strength were measured after the mellowing process. Laboratory test results have revealed that a single mellowing process with higher lime content and daily remixing at high temperature leads to the rapid reduction of sulfate content in the soil. Moreover, after the mellowing process, additional soil treatment with fly ash or a combination of lime and fly ash leads to lower expansion and higher retained unconfined compressive strength of the soil mixture.

Ethers. -The described method is easy, high-yielding and avoids the use of corrosive or moisture-sensitive reagents. -(SRIVASTAVA*, A.; YANG, J.; ZHAO, B.; JIANG, Y.; BLACKMON, W.; KRAEMER, B.; Synth.