Catalytic Hydrofunctionalization Reactions of 1,3-Diynes

Metal-catalyzed hydrofunctionalization reactions of alkynes, i.e., the addition of Y–H units (Y = heteroatom or carbon) across the carbon–carbon triple bond, have attracted enormous attention for decades since they allow the straightforward and atom-economic access to a wide variety of functionalized olefins and, in its intramolecular version, to relevant heterocyclic and carbocyclic compounds. Despite conjugated 1,3-diynes being considered key building blocks in synthetic organic chemistry, this particular class of alkynes has been much less employed in hydrofunctionalization reactions when compared to terminal or internal monoynes. The presence of two C≡C bonds in conjugated 1,3-diynes adds to the classical regio- and stereocontrol issues associated with the alkyne hydrofunctionalization processes’ other problems, such as the possibility to undergo 1,2-, 3,4-, or 1,4-monoadditions as well as double addition reactions, thus increasing the number of potential products that can be formed. In this review article, metal-catalyzed hydrofunctionalization reactions of these challenging substrates are comprehensively discussed.

Class Map: Improving Students’ Skills of Organic Synthesis in Learning Organic Chemistry for Pre-University Students

This action research uses the Kemmis & Mc Taggart Model (1988) to improve the skills for science stream of pre-university students in organic synthesis topic to convert one functional group to another by using Class Map in learning Organic Chemistry. The objectives of this study were to improve memory skills in conversion of functional groups in an Organic Chemistry reaction and to cultivate students' interest in the subject of Organic Chemistry. A total of six students of 6 Delta 2, SMK Sultan Abu Bakar were involved in this study. Preliminary surveys were conducted through observations, document analysis and interviews. The results of the survey showed that students could not remember the conversion of functional group well because in the Semester Three chemistry syllabus, there are too many chemical reactions, causing students less interested in learning Organic Chemistry. Students were exposed to the Class Map within two months. The test results displayed that (i) students can recall the functional group conversion reaction in an Organic Chemistry and (ii) students can apply the organic reactions learned in answering questions. The findings of the interviews showed that students can cultivate an interest in Organic Chemistry subject.

Supported Metal Catalysts for the Synthesis of N-Heterocycles

Nitrogen-containing heterocycles are important scaffolds for a large number of compounds with biological, pharmaceutical, industrial and optoelectronic applications. A wide range of different methodologies for the preparation of N-heterocycles are based on metal-catalyzed cyclization of suitable substrates. Due to the growing interest in Green Chemistry criteria over the past two decades, the use of supported metal catalysts in the preparation of N-heterocycles has become a central topic in Organic Chemistry. Here we will give a critical overview of all the solid supported metal catalysts applied in the synthesis of N-heterocycles, following a systematic approach as a function of the type of support: (i) metal catalysts supported on inorganic matrices; (ii) metal catalysts supported on organic matrices; (iii) metal catalysts supported on hybrid inorganic-organic matrices. In particular, we will try to emphasize the effective heterogeneity and recyclability of the described metal catalysts, specifying which studies were carried out in order to evaluate these aspects.

Electrophilic Iodination of Organic Compounds Using Elemental Iodine or Iodides: Recent Advances 2008–2021: Part I

The iodination of organic compounds is of great importance in synthetic organic chemistry. It opens comprehensive approaches for the synthesis of various biologically active compounds. The recent advances in iodination of organic compounds using elemental iodine or iodides, covering the last thirteen years, are the objective of the present review.

Electrification of a Milstein-type Catalyst for Alcohol Reformation

Novel energy and atom efficiency processes will be keys to develop the sustainable chemical industry of the future. Electrification could play an important role, by allowing to fine-tune energy input and using the ideal redox agent: the electron. Here we demonstrate that a commercially available Milstein ruthenium cata-lyst (1) can be used to promote the electrochemical oxidation of ethanol to ethyl acetate and acetate, thus demonstrating the four electron oxidation under preparative conditions. Cyclic voltammetry and DFT-calculations are used to devise a possible catalytic cycle based on a thermal chemical step generating the key hydride intermediate. Successful electrification of Milstein-type catalysts opens pathway to use alcohols as renewable feedstock for the generation of esters and other key building blocks in organic chemistry, thus contributing to increase energy efficiency in organic redox chemistry.

A aprendizagem de Química em meio a pandemia de Covid-19, período de 2021

Este trabalho apresenta um estudo de caso realizado nas disciplinas de Química Geral e Inorgânica, Química Orgânica e Fenômenos Químicos Aplicados que ocorreram no semestre B de 2021 em uma universidade comunitária. As experiências relacionam-se com aulas teóricas e práticas no período da pandemia da Covid-19. Todas elas ministradas pelo mesmo professor. Optou-se por fazer uma descrição dos resultados dos questionamentos realizados aos estudantes em uma roda de conversa. Apresenta-se a descrição dos resultados e ao finalizar a pesquisa percebe-se que os estudantes identificaram algumas fragilidades, principalmente nas aulas práticas realizadas por meio de laboratórios virtuais de aprendizagem, identificam que é uma ferramenta adequada, tratando-se da realidade de aulas remotas, mas entendem que as aulas práticas na modalidade presencial tem o seu devido valor, principalmente se tratando de Química. This work presents a case study carried out in the disciplines of General and Inorganic Chemistry, Organic Chemistry and Applied Chemical Phenomena that took place in the B semester of 2021 at a community university. The experiences are related to theoretical and practical classes during the Covid-19 pandemic period. All of them taught by the same teacher. It was decided to make a description of the results of the questions asked to students in a conversation circle. The description of the results is presented and, at the end of the research, it is clear that the students identified some weaknesses, especially in practical classes carried out through virtual learning laboratories, identifying that it is an adequate tool, considering the reality of remote classes , but they understand that the practical classes in the presential modality have their due value, especially when it comes to Chemistry.