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Croton lechleri, commonly known as Dragon’s blood, is a tree cultivated in the northwest Amazon rainforest of Ecuador and Peru. This tree produces a deep red latex which is composed of different natural products such as phenolic compounds, alkaloids, and others. The chemical structures of these natural products found in C. lechleri latex are promising corrosion inhibitors of admiralty brass (AB), due to the number of heteroatoms and π structures. In this work, three different extracts of C. lechleri latex were obtained, characterized phytochemically, and employed as novel green corrosion inhibitors of AB. The corrosion inhibition efficiency (IE%) was determined in an aqueous 0.5 M HCl solution by potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy, measuring current density and charge transfer resistance, respectively. In addition, surface characterization of AB was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. Chloroform alkaloid-rich extracts resulted in IE% of 57% at 50 ppm, attributed to the formation of a layer of organic compounds on the AB surface that hindered the dezincification process. The formulation of corrosion inhibitors from C. lechleri latex allows for the valorization of non-edible natural sources and the diversification of the offer of green corrosion inhibitors for the chemical treatment of heat exchangers.

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Two examples of bis 3,4-dialkoxythiophenes linked with a m-xylene bridge were synthesized in yields of 18% and 32% in a six step process. The formation of the m-xylene bridge, key reaction of the synthesis, was carried out through Williamson, Mitsunobu and trans-etherification reactions which were subsequently compared on performance and versatility. The Mitsunobu reaction assisted by sonication was found to be the best strategy. These molecules are among the few examples of unsymmetrically substituted 3,4-dialcoxythiophenes. During the synthesis an 18 member heterocycle, closely related to a crown ether was isolated. The details of the XRD structure of this heterocycle are discussed.