Radical transformations of organic solvents under sub- and supercritical conditions

A comparative study of chemical transformations of ethanol, acetone and dimethyl carbonate was performed in a temperature range from 200 to 300 °C. These compounds are widely used as solvents for processing vegetable raw materials. Therefore, knowing their behaviour in a reaction medium is necessary to understand the mechanism of sub- and supercritical extraction of the vegetable raw materials and the role of solvents in this processуы. It was established that the investigated compounds under certain conditions function as a source of free radicals; thus, they can contribute to the radical decomposition of the major components in plant biomass. The Schwarz toluene method was used to detect free radicals in reaction media. It is shown that radical breakdown of bonds in the acetone and dimethyl carbonate molecules occurs already at a temperature of 200 °C, and in ethanol - only under supercritical conditions at temperatures over 250 °C. Alkylation is the main reaction occurring during the thermal treatment of toluene and solvents mixtures, which leads to a high yield of various alkylbenzenes for all investigated xylene solvents. In a temperature range from 200 to 250 °С, acetone has the highest alkylating capability and ethanol - the lowest one. At temperatures above 250 °С, the alkylating capability of solvents is similar, with a slight prevalence of that of dimethyl carbonate. Unlike other solvents, acetone participates in nucleophilic addition reactions along with radical transformations under process conditions. The products obtained as a result of these reactions at temperatures above 250 °C are predominant. The main ones are the products of the aldol and crotonic condensation of acetone. Based on the results of a study, the pathways of the radical decomposition of solvents molecules and the formation of products of thermal treatment were proposed.

Wireless Sensor Network for Sustainable Agriculture

Precision agriculture can be defined as the science of using technology to improve the agricultural production. It is advisable for farmers to use a decision support system; in fact, real–time monitoring of climatic conditions is the only way to know the water needed by a cultivation. On the other hand, since the 1990s, a strong decrease of the Mediterranean Quercus has been observed in the pastures of southwestern Spain and Portugal, causing a high mortality of holm and cork oak trees. Among the factors associated with this decrease, the radical decomposition caused by Phytophthora Cinnamomi is remarkable for its gravity, which makes it necessary to reforest the trees and to monitor the microclimatic factors that have an influence on this regeneration. Wireless Sensor Networks (WSN) are a technology in full evolution and development, as well as their appropriate use in cultivations that help to implement ecological techniques. With these considerations in this work five units/nodes with one or more sensors that allow different environmental readings have been developed. In this work, the acquisition of data obtained from different sensors has been achieved, allowing the monitoring of climatic elements such as soil moisture, air quality, temperature and humidity, rainfall intensity, precipitation level, wind speed and direction, luminous flux and atmospheric pressure. A web page has been designed where the user can consult the climatic conditions of the cultivation or reforestation. Different devices interconnected with a central unit have been developed where measurements of the cultivation are sent for its later analysis by the farmer. The microclimatic data acquisition developed in the WSN proposed in this paper allows a farmer to make decisions about the irrigation of the cultivation, use of fertilizers, the development and maturation phases of the cultivated products, obtaining the optimum stages of cultivation and harvesting.

Mechanism of degradation of a nitrogenous heterocycle induced by a reductive radical: decomposition of a sym-triazine ring

Cyanuric acid, a major component of many materials and chemicals, and also the most important intermediate in the degradation processes of sym-triazine compounds in the natural environment, as well as being used for water treatment, was selected to elucidate the mechanism of degradation of nitrogenous materials.