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The study on the mechanism of the gas-phase elimination or thermal decomposition kinetics of 2, 2-dimethyl-3-butenal has been carried out by using theoretical calculation at MP2, combined ab initio CBSQB3 and DFT (B3LYP, B3PW91, MPW1PW91, PBEPBE, PBE1PBE, CAMB3LYP, M06, B97d) levels of theory. A good reasonable agreement between experimental and calculated parameters was obtained by using CAMB3LYP/6-311G(d,pd) calculations. The contrasted calculated parameters against experimental values suggested decarbonylation reaction to proceed through a concerted five-membered cyclic transition state type of mechanism, involving the hydrogen transfer from the carbonyl carbon to the gamma carbon, consistent with observed kinetic isotope effect. The breaking of alpha carbon–carbonyl carbon bond to produce carbon monoxide is 50% advanced in the transition state. The reaction mechanism may be described as a concerted moderately non-synchronous process. Examination of the Atoms in Molecules (AIM) analysis of electron density supports the suggested mechanism.

O trabalho apresenta um estudo da produção em História da Educação em Santa Catarina com base no que foi publicado em eventos científicos de caráter regional e nacional, entre os anos de 2000 e 2011. O objetivo é compreender as formas pelas quais se tece o entendimento sobre a escrita da história da educação no estado. Os eventos cotejados foram: os Congressos da SBHE, as Reuniões da ANPED e as reuniões da ANPED Sul. Mapear a produção historiográfica da educação catarinense, circunscrita aos trabalhos publicados nestes eventos, auxiliou na percepção desta historiografia nas injunções das leis de um lugar, de uma prática de pesquisa e de uma escrita constituídas institucional e historicamente e apropriado pelos sujeitos-pesquisadores

Resumo O caderno escolar é um objeto da cultura material que possibilita à História da Educação compreender o cotidiano da escola. Esse trabalho investigou as práticas de escrita em um caderno de produção de textos pertencente a uma ex-aluna da Escola Normal de Lages, interior do Estado de Santa Catarina, no ano de 1935. Nessa investigação o caderno representou um documento que permitiu entrever parte do processo de negociação entre o prescrito pelo currículo, o trabalho pedagógico e os tipos de escritas desenvolvidas pela normalista. Foram analisadas escritas presentes em redações, cartas e composições livres. O uso do caderno como documento possibilitou compreender as apropriações e os usos deste objeto como portador de sentidos ligados ao sistema de valores e representações sociais que ultrapassam a função de objeto destinado, somente, ao registro do processo de aprendizagem. Abstract The school notebook is an object of material culture that enables history of education to understanding the school's daily life. This work investigated the writing practices in a text production notebook belonging to a former student of the Normal School of Lages, State of Santa Catarina, in the year of 1935. In this research, the school notebook represented a tool that has allowed to see part of the negotiation process between the prescribed by the curriculum, the pedagogical work and the types of writing styles developed by the normalist. Writings were analyzed in texts, such as: essays, letters and free compositions. The use of the notebook as document/source made it possible to understand the appropriations and the uses of this object as bearer of meanings attached to a system of values and social representations that goes beyond the object function aimed only at the record of the learning process. Resumen El cuaderno escolar es un objeto de la cultura material que permite a la Historia de la Educación a entender lo cotidiano de la escuela. Este estudio investigó las prácticas de escritura en un cuaderno de producción de textos pertenecientes a una ex-alumna de la Escuela Normal de Lages, interior del Estado de Santa Catarina, en el año de 1935. En esta investigación, el cuaderno representa una herramienta que permite a vislumbrar parte del proceso de negociación entre prescrito por el currículo, el trabajo pedagógico y los tipos de escritura desarrollado por normalista. Se analizaron las escritas presentes en textos tales como ensayos, cartas y composiciones libres. El uso del cuaderno como un documento/ fuente ha permitido entender la apropiación y los usos de este objeto como portador de significado conectado con el sistema de valores y representaciones sociales que van más allá de la función objeto destinado sólo para el registro del proceso de aprendizaje. Résumé Le cahier d'école est un objet de la culture matérielle qui rend possible à l'Histoire de l'éducation comprendre le quotidien de l'école. Ce travail s'est intéressé pour les pratiques d'écriture dans un cahier de production de textes, appartenant a une ex-étudiante de L'Ecole Normale de Lages, dans l'État de Santa Catarina, dans l'année de 1935. Dans cette recherche, le cahier a représenté un outil qui permet pour identifier une partie du processus de négociation entre ce qui était prescrit dans le curriculum, le travail pédagogique et les écrits développés par l'étudiante. Des écrits présentés sous la forme de récits, lettres et essais ont été analysés. L'usage du cahier comme source d'information a rendu possible comprendre les appropriations et les usages de cet objet, comme porteur de sens liés au système de valeur et les représentations sociales qui vont au delà de la fonction objet destiné uniquement à l'enregistrement du processus d'apprentissage.

Este artigo apresenta o uso da rede social Facebook, tanto por educandos quanto por educadores, como um recurso tecnológico/pedagógico ao processo de ensino e aprendizagem na modalidade de Educação de Jovens e Adultos - EJA. O escopo desta investigação compreende que os desafios da proposta de uma educação emancipadora passam, também, pelo desenvolvimento e pela discussão sobre a presença e o uso das tecnologias digitais na vida cotidiana, com suas formas peculiares de sociabilidade. Em 2013, a Gerência de Educação do Programa de EJA do SESI, em Santa Catarina, criou no Facebook o Grupo O conhecimento move sua vida. Criado, no primeiro momento, com a função de comunicar e dar visibilidade às atividades desenvolvidas nos diferentes locais de funcionamento da EJA, este espaço virtual tornou-se um significativo e estratégico recurso de disseminação e compartilhamento de práticas e experiências de ensino e aprendizagem. Este artigo traz uma reflexão sobre o uso do Facebook como rede social virtual na educação, sobre a análise das informações publicadas por professores e alunos e, por fim, sobre as diferentes formas de apropriação e ressignificação dessa ferramenta. No âmbito da EJA do SESI, o Facebook contribui com a construção colaborativa do conhecimento e com o desenvolvimento de competências. Curtir, comentar e compartilhar são ações presentes na vida escolar e cotidiana dos sujeitos que vivenciam o processo educativo da EJA do SESI.

The kinetics of the gas-phase thermal decomposition of 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, and cyclopentanone ethylene ketal were determined in a static system and the reaction vessel deactivated with allyl bromide. The decomposition reactions, in the presence of the free radical suppressor propene, are homogeneous, are unimolecular, and follow first-order law kinetics. The products of these reactions are acetaldehyde and the corresponding ketone. The working temperature range was 459-490 °C, and the pressure range was 46-113 Torr. The rate coefficients are given by the following Arrhenius equations: for 2-methyl-1,3-dioxolane, log k = (13.61 ± 0.12) - (242.1 ± 1.0)(2.303RT)(-1), r = 0.9997; for 2,2-dimethyl-1,3-dioxolane, log k = (14.16 ± 0.14) - (253.7 ± 2.0)(2.303RT)(-1), r = 0.9998; for cyclopentanone ethylene ketal, log k = (14.16 ± 0.14) - (253.7 ± 2.0)(2.303RT)(-1), r = 0.9998. Electronic structure calculations using DFT methods B3LYP and MPW1PW91 with 6-31G(d,p), and 6-31++G(d,p) basis sets suggest that the decomposition of these substrates takes place through a stepwise mechanism. The rate-determining step proceeds through a concerted nonsynchronous four-centered cyclic transition state, and the elongation of the C-OCH(3) bond in the direction C(α)(δ+)...OCH(3)(δ-) is predominant. The intermediate products of these decompositions are unstable, at the working temperatures, decomposing rapidly through a concerted cyclic six-centered cyclic transition state type of mechanism.

The gas-phase thermal elimination of 2,2-diethoxypropane was found to give ethanol, acetone, and ethylene, while 1,1-diethoxycyclohexane yielded 1-ethoxycyclohexene and ethanol. The kinetics determinations were carried out, with the reaction vessels deactivated with allyl bromide, and the presence of the free radical suppressor cyclohexene and toluene. Temperature and pressure ranges were 240.1-358.3 °C and 38-102 Torr. The elimination reactions are homogeneous, unimolecular, and follow a first-order rate law. The rate coefficients are given by the following Arrhenius equations: for 2,2-diethoxypropane, log k(1) (s(-1)) = (13.04 ± 0.07) - (186.6 ± 0.8) kJ mol(-1) (2.303RT)(-1); for the intermediate 2-ethoxypropene, log k(1) (s(-1)) = (13.36 ± 0.33) - (188.8 ± 3.4) kJ mol(-1) (2.303RT)(-1); and for 1,1-diethoxycyclohexane, log k = (14.02 ± 0.11) - (176.6 ± 1.1) kJ mol(-1) (2.303RT)(-1). Theoretical calculations of these reactions using DFT methods B3LYP, MPW1PW91, and PBEPBE, with 6-31G(d,p) and 6-31++G(d,p) basis set, demonstrated that the elimination of 2,2-diethoxypropane and 1,1-diethoxycyclohexane proceeds through a concerted nonsynchronous four-membered cyclic transition state type of mechanism. The rate-determining factor in these reactions is the elongation of the C-O bond. The intermediate product of 2,2-diethoxypropane elimination, that is, 2-ethoxypropene, further decomposes through a concerted cyclic six-membered cyclic transition state mechanism.

The gas-phase elimination kinetics of N-benzylglycine ethyl ester was examined in a static system, seasoned with allyl bromide, and in the presence of the free chain radical suppressor toluene. The working temperature and pressure range were 386.4-426.7 degrees C and 16.7-40.0 torr, respectively. The reaction showed to be homogeneous, unimolecular, and obeys a first-order rate law. The elimination products are benzylglycine and ethylene. However, the intermediate benzylglycine is unstable under the reaction conditions decomposing into benzyl methylamine and CO(2) gas. The variation of the rate coefficients with temperature is expressed by the following Arrhenius equation: log k(1) (s(-1)) = (11.83 +/- 0.52) - (190.3 +/- 6.9) kJ mol(-1) (2.303RT)(-1). The theoretical calculation of the kinetic parameters and mechanism of elimination of this ester were performed at B3LYP/6-31G*, B3LYP/6-31+G**, MPW1PW91/6-31G*, and MPW1PW91/6-31+G** levels of theory. The calculation results suggest a molecular mechanism of a concerted nonsynchronous six-membered cyclic transition state process. The analysis of bond order and natural bond orbital charges implies that the bond polarization of C(=O)O-C, in the sense of C(=O)O(delta-)...C(delta+), is rate determining. The experimental and theoretical parameters have been found to be in reasonable agreement.

The gas phase elimination kinetics of racemic methyl mandelate was determined in a static system, and yielded on decomposition benzaldehyde, methanol, and carbon monoxide. The reaction was homogeneous, unimolecular, and follows a first-order law in the temperature range 379.5-440 degrees C and pressure range of 21.5-71.1 Torr. The variation of the rate coefficient with temperature is expressed by the following Arrhenius equation: log k1 = (12.70 +/- 0.14)-(206.5 +/- 1.9) kJ/mol (2.303RT)(-1). The theoretical estimations of the kinetics and thermodynamics parameters were carried out using DFT methods B3LYP, B3PW91, MPW1PW91, and PBEPBE. Calculation results are in reasonably good agreement with the experimental energy and enthalpy values when using the PBEPBE DFT functional. However, regarding the entropy of activation, the MPW1PW91 functional is more adequate to describe the reaction. These calculations imply a molecular concerted nonsynchronous mechanism involving a two-step process, where the formation of the unstable alpha-lactone intermediate is the rate-determining factor. The lactone intermediate rapidly decarbonylates to produce benzaldehyde and carbon monoxide. The transition state is late in the reaction coordinate, resembling the lactone configuration.

The reaction paths for the gas-phase molecular elimination of triethyl and trimethyl orthoesters were examined at B3LYP/6-31G(d,p), B3LYP/6-31G++(d,p), B3PW91/6-31G(d,p), B3PW91++G(d,p), MPW1PW91/6-31G(d,p), and MPW1PW91/6-31++G(d,p) levels of theory. The thermal decomposition of ethyl and methyl orthoesters involves similar transition state configurations in a four-membered ring arrangement. Products formed are ethanol and the corresponding unsaturated ketal for ethyl orthoesters, while in methyl orthoesters are methanol and the corresponding unsaturated ketal. Calculated thermodynamic and kinetic parameters from B3LYP calculations were found to be in good agreement with the experimental values. The calculated data imply the polarization of the C3-O4, in the direction C3(delta+)...O4(delta-), is rate determining. The NBO charges, bond indexes, and synchronicity parameters suggest the elimination reactions of ethyl orthoesters occur through a more polar asynchronic mechanism compared to methyl orthoesters.

The elimination kinetics of methyl trifluoropyruvate in the gas phase was determined in a static system, where the reaction vessel was always deactivated with allyl bromide, and in the presence of at least a 3-fold excess of the free-radical chain inhibitor toluene. The working temperature range was 388.5-430.1 degrees C, and the pressure range was 38.6-65.8 Torr. The reaction was found to be homogeneous and unimolecular and to obey a first-order rate law. The products of the reaction are methyl trifluoroacetate and CO gas. The Arrhenius equation of this elimination was found to be as follows: log k(1) (s(-1)) = (12.48 +/- 0.32) - (204.2 +/- 4.2) kJ mol(-1)(2.303RT)(-1) (r = 0.9994). The theoretical calculation of the kinetic and thermodynamic parameters and the mechanism of this reaction were carried out at the B3LYP/6-31G(d,p), B3LYP/6-31++G(d,p), MPW1PW91/6-31G(d,p), MPW1PW91/6-31++G(d,p), PBEPBE/6-31G(d,p), and PBEPBE/6-31G++(d,p) levels of theory. The theoretical study showed that the preferred reaction channel is a 1,2-migration of OCH(3) involving a three-membered cyclic transition state in the rate-determining step.

The rates of gas-phase elimination of trimethyl orthovalerate and trimethyl orthochloroacetate have been determined in a static system, and the reaction Pyrex vessels have been deactivated with the product of decomposition of allyl bromide. The reactions are unimolecular and follow a first-order rate law. The working temperature and pressure ranges were 313-410 degrees C and 40-140 Torr, respectively. The rate coefficients for the homogeneous reaction are given by the following Arrhenius expressions: for trimethyl orthovalerate: log k (s(-1)) = [(14.00 +/- 0.28) - (196.3 +/- 1.7) (kJ/mol)] (2.303RT)(-1), (r = 0.9999); and for trimethyl orthochloroacetate: log k (s(-1)) = [(13.54 +/- 0.21) - (209.3 +/- 1.9)(kJ/mol)](2.303RT)(-1), (r = 0.9998). The theoretical calculations of the kinetic and thermodynamic parameters were carried out by using B3LYP, B3PW91, MPW1PW91, and PBEPBE methods. The theoretical results show reasonably good agreement with the experimental energy and enthalpy of activation values when using the B3PW91/6-31++G** method for trimethyl orthovalerate and PBEPBE /6-31++G** for trimethyl orthochloroacetate. These calculations suggest a molecular concerted nonsynchronous mechanism where C-OCH(3) bond polarization, in the sense C(delta+)...(delta-)OCH(3), is the rate-determining step. The increase in electron density of the oxygen atom at OCH(3) eases the abstraction of the hydrogen of the adjacent C-H bond in a four-membered cyclic structure to give methanol and the corresponding unsaturated ketal. The electron-donor substituent enhances decomposition rates by stabilizing the positive charge developing in the transition state at the carbon bearing the three methoxy groups, whereas the electron-withdrawing substituent destabilizes this charge, thus retarding the reaction.

Methyl 2,2-dimethyl-3-hydroxypropionate was found to decompose, in a static system, mainly to methyl isobutyrate and formaldehyde. The reaction rates were affected in packed and unpacked clean Pyrex vessels, demonstrating little but significant surface effect. However, in vessels seasoned with allyl bromide this reaction was homogeneous and unimolecular and followed a first-order law. The working temperature range was 349-410 degrees C and the pressure range was 64-162 Torr. The variation of the rate coefficient with temperature is expressed by the following Arrhenius expression: log k(1) (s(-1)) = [(11.43 +/- 0.57) - (180.4 +/- 7.2) kJ mol(-1)] x (2.303RT)(-1). Methyl 2,2-dimethyl-3-hydroxypropionate was found to be 1.4 times greater in the rate of elimination than methyl 3-hydroxypropionate. Apparently, steric acceleration may be considered responsible in the process of decomposition. The theoretical calculation of the kinetics and thermodynamics parameters, at the B3LYP/6-211G** level of theory, are in reasonably good agreement with the experimental values obtained. These calculations imply a molecular mechanism involving a concerted nonsynchronous transition state where abstraction of the hydroxyl hydrogen by the oxygen of the carbonyl ester is a determining factor and the transition state is late in the reaction coordinate.