Recentes aplicações sintéticas de compostos orgânicos tricloro(bromo)metila substituídos

This review presents the recent applications of some trihalomethyl carbinols, α,α,α-trihalogenated carbonyl compounds and trichloro(bromo)methyl-containing heterocycles, acting as high versatile synthetic precursors in organic chemistry, based on the last 10 years' literature.

O ensino superior de química: reflexões a partir de conceitos básicos para a química orgânica

We live in a context in which knowledge develops continuously and rapidly. This generates a social dynamics that demands constant adaptation from those living in society and also from educational institutions. Education for this new society needs to be rethought. Universities, anchored in tradition, still use a transmission/reception model of education. A data-collecting instrument applied to undergraduate chemistry students at the end of the course in organic chemistry investigated some concepts essential to the education of a chemist, such as interatomic and intermolecular interactions and Lewis structure. We observed that students have difficulty dealing with these concepts, and we believe that this is related to the type of class they had/have and to the way the concepts are presented in the college textbooks.

Investigando cinza da casca do arroz como fase estacionária em cromatografia: uma proposta de aula experimental nos cursos de graduação

This article describes an experiment that involves the extraction and separation of the pigments of spinach extract by column chromatography using the silica obtained from rice husk ash as a stationary phase. The experimental procedure is very simple to apply in the chemistry laboratory, and allowed to illustrate some concepts of organic chemistry: structure of organic molecules, solubility, polarity, extraction, partition coefficient, adsorption and retention factor (Rf), as well as objectives and fundamentals of chromatographic methods. The experiment can be carried out in a 4 h period.

Biomassa em aula prática de Química Orgânica Verde: cravo-da-índia como fonte simultânea de óleo essencial e de furfural

This work presents an optimized integrated experiment for isolation of clove bud essential oil, rich in eugenol, and subsequent utilization of the solid residue for furfural synthesis. The operationally simple laboratory protocols and utilization of water as a solvent in both operations, plus the use of biomass as the starting material for preparation of versatile intermediates in organic synthesis, make the experiments attractive for undergraduate experimental organic chemistry courses in the context of green chemistry. In addition, this is the first description of the use of biomass (clove bud) in the simultaneous preparation of two chemical feedstocks, eugenol and furfural, on experimental organic chemistry courses.

Condensação de Knoevenagel de aldeídos aromáticos com o ácido de Meldrum em água: uma aula experimental de Química Orgânica Verde

This work describes an undergraduate experiment for the synthesis of Knoevenagel adduct of Meldrum's acid with nine aromatic aldehydes, using water as the solvent, in an adaptation of a previously reported synthetic protocol. The synthesis was straightforward, requiring a period of two hours, and is suitable for undergraduate experimental courses on green chemistry. In addition, quantitative analyses of the relative reactivity of p-nitro-benzaldehyde and p-metoxi-benzaldehyde was evaluated through the competitive reaction of equimolar amounts of these aldehydes with one equivalent of Meldrum's acid, using gas chromatography to quantify the composition of the reaction mixture.

Adição de anilinas à naftoquinona em água e em fase sólida

Considering all the aspects of the principles of green chemistry, we present herein the addition reactions of amines to 1,4-naphthoquinone in water as solvent and also in solid phase. These reactions resulted in very colorful products that were easily monitored by thin layer chromatography and consequently easy to separate. Therefore, they are interesting experiments for experimental organic chemistry in the classrooms or in the laboratories.

Furfural - da biomassa ao laboratório de química orgânica

The goal of this manuscript is provide to students of Chemistry and related areas an alternative experiment in which they can obtain a compound and learn to observe and interpret properties and predict organic structure by obtaining furfural from biomass. Furfural is an organic compound, obtained through acid hydrolysis of pentosans, commonly used in the chemical and pharmaceutical industries. Students are guided to get furfural through extractive procedures and chemical reactions adapted to semi-micro laboratory scale. Characterization of furfural was done by chemical tests and physical properties. Identification was accomplished by a series of spectroscopic and spectrometric techniques.

Síntese da Epoxone a partir de D-frutose: um experimento didático em laboratório de Química Orgânica com foco nos princípios da Química Verde

In recent years, the introduction of the Green Chemistry concepts in undergraduate chemistry classes has been intensively pursued. In this regard, the two-step preparation of Epoxone (an organocatalyst developed by Shi & col.) from commercial D-fructose, through ketalization of vicinal diols followed by oxidation of a sterically congested secondary alcohol, involves important topics in Organic Chemistry and employs inexpensive and nontoxic reagents. The reactions are easy to perform and the products from both steps are readily obtained as crystalline solids after simple procedures, thus facilitating their chemical characterization.

Reações multicomponentes de Biginelli e de Mannich nas aulas de química orgânica experimental: uma abordagem didática de conceitos da química verde

The introduction of Mannich and Biginelli multicomponent reactions in a practical Organic Chemistry course is presented in this article. Procedures described in the literature were adapted for use under the simple conditions available in undergraduate laboratories and were selected on the basis of Green Chemistry principles and practicality of synthesis. The reactions are easy to carry out and all products are readily isolated as crystalline solids with yields ranging from moderate to high.

Montagem de uma prensa para fios de sódio metálico

Several organic chemistry labs in Brazil suffers from the absence of a safe method to extrude sodium wire, used to obtain anhydrous solvents such as THF or ethyl ether. This technical note presents the assembly instructions for a sodium wire press, similar to the one that has been used for the past four years in our laboratory without any maintenance.

Síntese e hidrólise de azalactonas de Erlenmeyer-Plöchl mediadas por radiação micro-ondas em aparelhos doméstico e dedicado: experimentos de química orgânica para a graduação

This work describes a green chemistry experiment for the synthesis of Erlenmeyer-Plöchl azalactones mediated by microwave irradiation, employing both dedicated and domestic equipment. Hippuric acid was reacted with equimolar amounts of benzaldehyde, p-chloro-benzaldehyde or p-N,N-dimethyl-benzaldehyde in acetic anhydride as the solvent. Acid hydrolysis of obtained 4-benzylidene-2-phenyloxazol-5(4H)-one under microwave and convectional heating afforded Z-α-(benzoylamino)cinnamic acid at a 51-61.5% yield. The UV-Vis molecular spectra of 4-benzylidene-2-phenyloxazol-5(4H)-one and 4-(4'-N,N-dimethylbenzylidene)-2-phenyloxazol-5(4H)-one were obtained in ethanol, CH2Cl2 and DMSO and bathochromic shift was observed for the latter azalactone.

Preparação de derivados do lapachol em meio ácido e em meio básico: uma proposta de experimentos para a disciplina de Química Orgânica Experimental

In this educational paper we describe the extraction of lapachol from its natural source according to acid-base concepts in organic chemistry and the use of its derivatives β-lapachone and hydroxy-hydrolapachol to exemplify intramolecular cyclization, carbocation stability, Michael addition reaction and chromatography. The experiments were performed during three different undergraduate organic chemistry laboratory classes using low cost material, while avoiding color reagents for TLC visualization, as well as small-scale column chromatography to isolate the mixture of lapachol and β-lapachone.

A importância da lei de Gay-Lussac para a classificação dos compostos orgânicos

This article shows the genesis of the law of volumes of combining gases, formulated by Gay-Lussac in 1808, and how it allowed the expression of the composition of organic compounds in terms of whole numbers of volumes, thus leading to the first classification of organic compounds, formulated by Dumas and Boullay in 1828. It was from this work that Organic Chemistry began to shed its purely taxonomic nature, analogous to what prevailed in Natural History, and to then develop in a vigorous and continuous process, initiating what may be the most significant historical phenomenon in the History of Chemistry of the nineteenth century.

Miniprojeto para ensino de Química Orgânica Experimental baseado no acoplamento catalítico N-C promovido por micro-ondas

This paper describes a three-week mini-project for an Experimental Organic Chemistry course. The activities include N-C cross-coupling synthesis of N-(4-methoxyphenyl) benzamide in an adapted microwave oven by a copper catalyst (CuI). Abilities and concepts normally present in practical organic chemistry courses are covered: use of balances, volumetric glassware, separation of mixtures (liquid-liquid extraction and filtration), chromatographic techniques, melting point determination and stoichiometric calculations.

Inovação & propriedade industrial & indústria química

ABSTRACT The main aim of this paper was to contribute to reflections in Brazil on the need to transfer knowledge held at universities and R&D institutions over to companies, i.e. to transfer scientific knowledge of chemistry to technology. It discusses how the competitiveness of countries is increasingly dependent on their technological capacity. The chemicals industry is a fundamental driver of social, environmental, economic and industrial indicators of sustainable development. In Brazil, the chemicals industry's deficit has grown over the last three decades. Patents are important sources of information because patent documents contain 75% of all technological information available. The National Institute of Industrial Property in Brazil has created a Technology Observatory with the purpose of identifying and analyzing technological information contained in patent documents within the ambit of partnerships with government entities or business associations, in order to support their technology-related decision-making processes. The paper gives examples of ethanol and biotechnology patent documents, including pharmaceuticals, of which there are very few in Brazil. However, a few of the patent applications identified are filed in Brazil, giving the country the opportunity to transform this scientific knowledge into technology by means of partnership agreements with companies. Finally, the paper presents information on the patent applications filed by the world's leading chemicals companies as measured by their revenues, and the respective numbers of patent applications in the last five years in organic chemistry and polymers, sectors in which Brazil is currently dependent on imports for over 50% of its needs. The patent assignees in these sectors in Brazil are also identified, and the paper concludes that Brazil needs to invest in the development of professionals, providing clearly-defined career paths in technology innovation teams at R&D institutions, and to foster more initiatives such as the creation of a new research and innovation entity, EMBRAPII, since investing in science and technology is a prerequisite for knowledge production, industrial property, economic development and, consequently, the competitiveness of the country.