A detailed computational study of the dehydrogenation reaction of trans-propylamine (trans-pA) in the gas phase has been performed using density functional method (DFT) and CBS-QB3 calculations. Different mechanistic pathways were studied for the reaction of n-propylamine. Both thermodynamic functions and activation parameters were calculated for all investigated pathways. Most of the dehydrogenation reaction mechanisms occur in a concerted step transition state as an exothermic process. the mechanisms for pathways A and B comprise two key-steps: H 2 eliminated from pA leading to the formation of allylamine that undergoes an unimolecular dissociation in the second step of the mechanism. Among these pathways, the formation of ethyl cyanide and H 2 is the most significant one (pathway B), both kinetically and thermodynamically, with an energy barrier of 416 kJ mol −1. the individual mechanisms for the pathways from c to n involve the dehydrogenation reaction of PA via hydrogen ion, ammonia ion and methyl cation. The formation of α-propylamine cation and nH 3 (pathway E) is the most favorable reaction with an activation barrier of 1 kJ mol −1. this pathway has the lowest activation energy calculated of all proposed pathways. Propylamine is of significant importance in chemistry, as it constitutes a central structure block for aliphatic amines 1. It is widely utilized as a solvent in organic synthesis, and as a finishing agent for drugs, rubber, fiber, paints, pesticides, textile and resin 2,3 , and in the generation of fungicides 4-6. Furthermore, it may very well be used as a petroleum additive and preservative. The disintegration of protonated of propylamine has attracted a noteworthy arrangement of fascination in the previous decade 7-10. This is mainly due to the way that the proton affinity and the structural difference in propylamine through protonation influences the separation items through the arrangement of protonated amines, methane, propene and hydrogen gas 11,12. Additionally, this reaction prompts the generation of various poisonous synthetic substances such as, alkyl cyanide, propylene, ethylene, nitrogen and hydrogen gases 13,14. Protonation (B + H + → BH +) and deprotonation (dehydrogenation) (HA − H + → A −) reactions assume a significant role in natural science and organic chemistry, where A and B are the acidic and the basic centers, respectively. They are considered as the first step in several fundamental chemical mechanisms elucidated in the cited reference 15. The ability of an atom or molecule in the gas phase to accept or to lose a proton can be described by calculating the proton affinity (PA), deprotonation (dehydrogenation) enthalpy, and molecular gasphase basicity, which offer a profound understanding of the connections between the reactivity of the organic molecules, their molecular structures, and molecular stability 16. The negative of the enthalpy change related to the gas-phase protonation reaction is referred to as proton affinity, while dehydrogenation energy is defined as the en...

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The conversion of brown grease using pyrolysis reactions represents a very promising option for the production of renewable fuels and chemicals. Brown grease forms a mixture of alkanes, alkenes, and ketones at a temperature above 300°C at atmospheric pressure. This work is a computational study of the detailed reaction mechanisms of brown grease pyrolysis using DFT methodology. Prior experimental investigations confirmed product formation consistent with a set of radical reactions with CO2 elimination, as well as ketone by product formation, CO forming reactions, and formation of alcohols and aldehydes as minor byproducts. In this work, computational quantum chemistry was used to explore these reactions in greater detail. Particularly, a nonradical pathway formed ketone byproducts via the ketene, which we refer to as Pathways A1 and A2. Radical formation by thermal decomposition of unsaturated fatty acids initiates a set of reactions which eliminate CO2, regenerating alkyl radicals leading to hydrocarbon products (Pathway B). A third pathway (Pathway C) is an alternative set of radical reactions, resulting in decarbonylation and formation of minor byproducts. The results of the calculations are in good agreement with recent experimental studies.

The analytical performance of cumulative area pre-processing (CAP), a recently developed signal filtering method, along with multivariate calibration for quantification of spectrally overlying drugs was outlined. The drug combinations containing high level of paracetamol (PAR) in the presence of caffeine (CAF), chlorpheniramine maleate (CHL), pseudoephedrine hydrochloride (PSE), phenylephrine hydrochloride (PHE), and diphenhydramine hydrochloride (DPH). The tested formulations were: PAR-CAF-PHE, PAR-CAF-PHE, and PAR-DRH. Based on netanalyte signal calculations, the formulations exhibited intense overlapping 53-68% for PAR-PSE-CHL, 55-95% for PAR-CAF-PHE, and 44% for PAR-DRH. For each system, PLS latent variables were estimated using cross-validation technique and more factors were needed for highly overlapping systems. PLS-CAP was found applicable for drugs quantification in all systems with excellent performance regardless the size of spectral overlapping and ratios of components in the formulation. For PAR-PSE-CHL (ratio 300:30:2 mg/tablet), the ingredients were quantified by CAP-PLS with satisfactorily recoveries (RSD, n = 3) 89.9% (3.1%), 104.6% (2.7%), and 99.0% (1.5%) for PAR, PSE, and CHL, respectively. Both PLS and CAP-PLS were demonstrated the same performance for binary system of modest overlapping and no component available in low concentration.