Fulereno[C60]: química e aplicações

Fullerene chemistry has become a very active research field in the two last decades, largely because of the exceptional properties of the C60 molecule and the variety of fullerene derivatives that appear to be possible. In this review, a general analysis of fullerene C60 reactivity is performed. The principal methods for the covalent modification of this fascinating carbon cage are presented. The prospects of using fullerene derivatives as medicinal drugs and photoactive materials in light converting devices are demonstrated.

Calorímetro de gelo: uma abordagem histórica e experimental para o ensino de química na graduação

In addition to the usual advantage of an ice calorimeter of being able to measure slow heat changes, the instrument described here is extremely simple to construct and operate. Specific heat of aluminum, copper, lead and tin metals were determined using the ice calorimeter made with easily accessible materials. The values obtained from specific heat are near to those found in the literature and were 0.204; 0.030; 0.086; 0.046 cal/g °C with an error of theoretical values of 6.84; 1,64; 5.49 and 8.00% for aluminum, copper, lead and tin, respectively.

Ações de divulgação de química na Casa da Descoberta - centro de divulgação de ciência da Universidade Federal Fluminense

This paper describes the main activities regarding scientific dissemination in the field of Chemistry at Casa da Descoberta (CD) - a Scientific Dissemination Center of the Fluminense Federal University. It presents a brief history of CD and discusses the difficulties concerning the dissemination of Chemistry at Scientific Dissemination Centers. This work also approaches some activities developed throughout the years: experiments performed in relation to the visitors' daily life, training of monitors to act as mediators in the non-formal teaching of Chemistry, production of dissemination materials, elaboration of books, as well as activities that relate formal to non-formal education.

Caracterização físico-química de filmes comestíveis de amido adicionado de acerola (Malphigia emarginata D.C.)

Edibles films are an alternative to synthetic materials used for packing food products. Barbados cherry is rich in vitamin C and carotenoids. The aim of this study was to characterize and develop films by casting from cassava starch, lyophilized Barbados cherry pulp and glycerol. The films were characterized with respect to thickness, water vapor permeability (WVP), water solubility, vitamin C, carotene and mechanical properties. The interaction of pulp and glycerol reduced film thickness. An increase in pulp concentration up to 60% increased WVP but beyond this concentration reduced both WVP and solubility leading to an increased level of vitamin C and β carotene in the films.

Romp as a versatile method for the obtention of differentiated polymeric materials

Ring Opening Metathesis Polymerization (ROMP) of cyclic olefins is a powerful transition metal-catalyzed reaction for syntheses of polymers and copolymers. The key feature of this reaction is the [2+2]-cycloaddition mechanism, with retention of the olefinic unsaturation in the polymer chain and occurrence of living polymerization. With the development of metal-carbene type catalysts for this process, many addressed polymeric materials have been successfully prepared to be employed in several fields of the science and technology. This review summarizes recent examples of syntheses of polymers with amphiphilic features such as block, graft, brush or star copolymers; as well syntheses of biomaterials, dendronized architectures, photoactive polymers, cross-linked or self-healing materials, and polymers from renewed supplies.

Caracterização através de análise química da escultura portuguesa sobre madeira de produção erudita e de produção popular da época barroca

Making use of several analytical techniques, four erudite and four popular Portuguese baroque wooden sculptures were studied. The materials and techniques employed were identified and the relationship between their artistic quality and the materials used was investigated. In general, the pigments were common at the time, but one pigment discovered in the beginning of the 18th century and two rare arsenic pigments were also identified. In popular sculptures cost-saving was detected, particularly concerning the gold leaf. Regarding some technical procedures identified, recommendations found in historical documents did not seem to have been entirely followed, neither in erudite nor in popular sculptures.

Síntesis química, estudios de caracterización y reactividad de un material catalítico a base de ZrO2-H3PW12O40

In this work, the preparation and characterization of materials such as zirconium oxide (ZrO2) and phosphotungstic acid promoted zirconium oxide (ZrO2-H3PW12O40) is presented. Physico-chemical characterization results showed that addition of H3PW12O40 acted as both a textural and chemical promoter of zirconium oxide. The incorporation of phosphotungstic acid into the ZrO2 matrix delayed the sintering of the material and stabilized ZrO2 in the tetragonal phase. ZrO2 acidity was also enhanced, developing strong acid sites on its surface. The Pt/ZrO2-H3PW12O40 catalyst was active for n-pentane isomerization at 250 °C, exhibiting high selectivity to iso-pentane (95%). This result is probably due to its suitable acidity.

Carboidratos como fonte de compostos para a indústria de química fina

Coal, oil, natural gas, and shale gas are biomass that is formed millions of years ago. These are non-renewable and depleting, even considering the recent discovery of new sources of oil in the presalt and new technologies for the exploitation of shale deposits. Currently, these raw materials are used as a source of energy production and are also important for the production of fine chemicals. Since these materials are finite and their (oil) price is increasing, it is clear that there will be a progressive increase in the chemical industry to use renewable raw materials as a source of energy, an inevitable necessity for humanity. The major challenge for the society in the twenty first century is to unite governments, universities, research centers, and corporations to jointly act in all areas of science with one goal of finding a solution to global problems, such as conversion of biomass into compounds for the fine chemical industry.Non-renewable raw materials are used in the preparation of fuels, chemical intermediates, and derivatives for the fine chemical industry. However, their stock in nature has a finite duration, and their price is high and will likely increase with their depletion. In this scenario, the alternative is to use renewable biomass as a replacement for petrochemicals in the production of fine chemicals. As the production of biomass-based carbohydrates is the most abundant in nature, it is judicious to develop technologies for the generation of chain products (fuels, chemical intermediates, and derivatives for the fine chemicals industry) using this raw material. This paper presents some aspects and opportunities in the area of carbohydrate chemistry toward the generation of compounds for the fine chemical industry.

Panorama de propriedade intelectual, transferência de tecnologia e inovação da química brasileira e a comparação com os países do BRIC

Based on Science, Technology & Innovation (ST&I) indicators, Brazil is a competitive and interesting country from the point of view of technological foreign investment. However, it is still incipient with regard to national investments, production of technological knowledge, inbound mobility of scientists and technology transfer to the productive sector. Among many other factors, global patent production is considered as an important indicator of innovation. Likewise, the balance between revenue and expenses obtained through royalties and licensing fees of technologies is also critical in mapping the diffusion and absorption of knowledge. The understanding of intellectual property and its strategic management brings a significant advantage to the economic and technological development of nations, especially in the field of chemistry, which greatly contributes to biotechnology, new materials and microelectronics - three fundamental areas for innovation in developed countries. Therefore, this article aims to map out competencies in chemistry in Brazil and evaluate science, technology and innovation indicators in the country, comparing this dynamic to the one of other BRIC members (Russia, India and China). Chemistry is the fourth biggest field of interest in Brazil based on the number of researchers registered at the governmental platform for researchers, Plataforma Lattes/CNPq, and is preceded by education, medicine and agronomy. The majority of research groups are registered in the area of materials, followed by macromolecules and polymers, pharmaceutical products and basic materials chemistry. These groups represent approximately 77% of research groups analyzed, therefore, indicating a tendency in the country. The analyses of patents in different sub-areas of chemistry reveal that non-residents file most deposits in the country, a probable reflection of the low internal intellectual property culture. Pharmaceutics and Fine Chemistry are prominent areas in the country, in line with the global trend. Among BRIC countries, China has the highest number of patents and of requests for protection in international offices. On the other hand, Brazil has the lowest number of chemical patents published at USPTO, EPO and JPO. An analysis of the transfer of technology data indicates an increase in this activity in various sub-areas of chemistry in the country. Despite the great efforts made by the country to consolidate its national innovation system, more needs to be done to put Brazil in a competitive position. In a globalized world dominated by large players, Brazil needs a lot of progress on ownership and generation of chemistry technologies to strengthen its national sovereignty. It is essential to strengthen chemical research at all levels, from elementary school to university, as an inexhaustible source of knowledge and technology that, when properly protected, may generate real public achievement and social return.

Química Sem Fronteiras: o desafio da energia

Coal, natural gas and petroleum-based liquid fuels are still the most widely used energy sources in modern society. The current scenario contrasts with the foreseen shortage of petroleum that was spread out in the beginning of the XXI century, when the concept of "energy security" emerged as an urgent agenda to ensure a good balance between energy supply and demand. Much beyond protecting refineries and oil ducts from terrorist attacks, these issues soon developed to a portfolio of measures related to process sustainability, involving at least three fundamental dimensions: (a) the need for technological breakthroughs to improve energy production worldwide; (b) the improvement of energy efficiency in all sectors of modern society; and (c) the increase of the social perception that education is a key-word towards a better use of our energy resources. Together with these technological, economic or social issues, "energy security" is also strongly influenced by environmental issues involving greenhouse gas emissions, loss of biodiversity in environmentally sensitive areas, pollution and poor solid waste management. For these and other reasons, the implementation of more sustainable practices in our currently available industrial facilities and the search for alternative energy sources that could partly replace the fossil fuels became a major priority throughout the world. Regarding fossil fuels, the main technological bottlenecks are related to the exploitation of less accessible petroleum resources such as those in the pre-salt layer, ranging from the proper characterization of these deep-water oil reservoirs, the development of lighter and more efficient equipment for both exploration and exploitation, the optimization of the drilling techniques, the achievement of further improvements in production yields and the establishment of specialized training programs for the technical staff. The production of natural gas from shale is also emerging in several countries but its production in large scale has several problems ranging from the unavoidable environmental impact of shale mining as well as to the bad consequences of its large scale exploitation in the past. The large scale use of coal has similar environmental problems, which are aggravated by difficulties in its proper characterization. Also, the mitigation of harmful gases and particulate matter that are released as a result of combustion is still depending on the development of new gas cleaning technologies including more efficient catalysts to improve its emission profile. On the other hand, biofuels are still struggling to fulfill their role in reducing our high dependence on fossil fuels. Fatty acid alkyl esters (biodiesel) from vegetable oils and ethanol from cane sucrose and corn starch are mature technologies whose market share is partially limited by the availability of their raw materials. For this reason, there has been a great effort to develop "second-generation" technologies to produce methanol, ethanol, butanol, biodiesel, biogas (methane), bio-oils, syngas and synthetic fuels from lower grade renewable feedstocks such as lignocellulosic materials whose consumption would not interfere with the rather sensitive issues of food security. Advanced fermentation processes are envisaged as "third generation" technologies and these are primarily linked to the use of algae feedstocks as well as other organisms that could produce biofuels or simply provide microbial biomass for the processes listed above. Due to the complexity and cost of their production chain, "third generation" technologies usually aim at high value added biofuels such as biojet fuel, biohydrogen and hydrocarbons with a fuel performance similar to diesel or gasoline, situations in which the use of genetically modified organisms is usually required. In general, the main challenges in this field could be summarized as follows: (a) the need for prospecting alternative sources of biomass that are not linked to the food chain; (b) the intensive use of green chemistry principles in our current industrial activities; (c) the development of mature technologies for the production of second and third generation biofuels; (d) the development of safe bioprocesses that are based on environmentally benign microorganisms; (e) the scale-up of potential technologies to a suitable demonstration scale; and (f) the full understanding of the technological and environmental implications of the food vs. fuel debate. On the basis of these, the main objective of this article is to stimulate the discussion and help the decision making regarding "energy security" issues and their challenges for modern society, in such a way to encourage the participation of the Brazilian Chemistry community in the design of a road map for a safer, sustainable and prosper future for our nation.

Catálise assimétrica no Brasil: desenvolvimento e potencialidades para o avanço da indústria química brasileira

The preparation of enantiomerically pure or enriched substances is of fundamental importance to pharmaceutical, food, agrochemical, and cosmetics industries and involves a growing market of hundreds of billions of dollars. However, most chemical processes used for their production are not environmentally friendly because in most cases, stoichiometric amounts of chiral inductors are used and substantial waste is produced. In this context, asymmetric catalysis has emerged as an efficient tool for the synthesis of enantiomerically enriched compounds using chiral catalysts. More specifically, considering the current scenario in the Brazilian chemical industry, especially that of pharmaceuticals, the immediate prospect for the use of synthetic routes developed in Brazil in an enantioselective fashion or even the discovery of new drugs is practically null. Currently, the industrial production of drugs in Brazil is primarily focused on the production of generic drugs and is basically supported by imports of intermediates from China and India. In order to change this panorama and move forward toward the gradual incorporation of genuinely Brazilian synthetic routes, strong incentive policies, especially those related to continuous funding, will be needed. These incentives could be a breakthrough once we establish several research groups working in the area of organic synthesis and on the development and application of chiral organocatalysts and ligands in asymmetric catalysis, thus contributing to boost the development of the Brazilian chemical industry. Considering these circumstances, Brazil can benefit from this opportunity because we have a wide biodiversity and a large pool of natural resources that can be used as starting materials for the production of new chiral catalysts and are creating competence in asymmetric catalysis and related areas. This may decisively contribute to the growth of chemistry in our country.

Nanoporous materials: pillared clays and regular silicas as an example of synthesis and their porosity characterization by X-ray diffraction

Because of their practical applications, porous materials attract the attention of undergraduate students in a way that can be used to teach techniques and concepts in various chemistry disciplines. Porous materials are studied in various chemistry disciplines, including inorganic, organic, and physical chemistry. In this work, the syntheses of a microporous material and a mesoporous material are presented. The porosity of the synthesized materials is characterized by X-ray diffraction analysis. We show that this technique can be used to determine the pore dimensions of the synthesized materials.

Síntese de cristais líquidos derivados do nitroazobenzeno: uma proposta de síntese multi-etapas aplicada às aulas de química orgânica experimental

We describe a synthetic route consisting of five steps from aniline to obtain liquid crystal compounds derived from nitroazobenzene. Syntheses were performed during the second half of the semester in organic chemistry laboratory classes. Students characterized the liquid crystal phase by the standard melting point techniques, differential scanning calorimetry and polarized optical microscopy. These experiments allow undergraduate students to explore fundamentally important reactions in Organic Chemistry, as well as modern concepts in Chemistry such as self-assembly and self-organization, nanostructured materials and molecular electronics.

Análise química da biomassa - uma revisão das técnicas e aplicações

Use of biomass as an alternative to nonrenewable feedstock for energy, materials, and chemicals is currently a prominent theme for industry and R Countries like Brazil, USA, and Germany are spending resources and efforts to promote a green economy based on biomass supply chains. Chemical analysis is an important tool to ensure quality, reliability, and to suggest the best potential use for the biomass, thereby enhancing its economic potential. Analytical techniques can identify chemical components, characterize their properties, and determine their concentration. This article discusses the commonly employed techniques and their application in chemical analysis of biomass and its products.

O que sabemos sobre os primeiros livros didáticos brasileiros para o ensino de Química

This paper deals with the Brazilian textbooks of Chemistry from the XIX century to 1930. After presenting the science and its teaching contexts in Imperial Brazil and describing the first Chemistry textbook written by a Brazilian, the state of knowledge about these prime Brazilian books is presented. These works show the texts had strengths overlooked by current materials, a fact confirmed by analyzing textbooks from three authors from the period. The study concludes by compiling a list of 50 titles of early Chemistry books to help guide future research.