Do termoscópio ao termômetro digital: quatro séculos de termometria

This work describes the evolution of temperature measurement in the last four centuries using thermometers based on the thermal expansion of liquids such as ethyl alcohol and mercury. The concept of temperature was strongly dependent on the researcher and there was no systematic temperature scale for universal use. The precursor of the common thermometer was the thermoscope, probably invented at the end of the XVIth century. In the XVIIIth century the instrument was greatly improved and several thermometric scales were proposed some of which have been in use until now. These scales were based on arbitrary points. Mercury and ethyl alcohol were the most employed thermometric fluids. In the XIXth century, the concept of absolute zero was a great advance in this field. The most important contribution during the XXth century was the establishment of international temperature scales. The design of the thermometer has been essentially the same along the last 300 years, but many models were proposed for industrial and research purposes. Its association with the densimeter was of great importance for control of industrial chemical processes and also for teaching purposes in the past. Nowadays, there is a clear tendency to replace mercury-based thermometers by electronic digital models. Thermochemistry is the natural relationship between temperature and chemistry.

Constituintes químicos de Philodendron imbe Schott

The chemical composition of the ethanolic extract of the leaves and roots from Philodendron imbe Schott was investigated. The main constituents isolated the leaves were beta-sitosterol one polyprenoid hexaprenol, and 6beta-hydroxy-stigmast-4-en-3-one, a steroid, not yet reported in the Philodendron gender. A mixture of constituents, namely, ethyl myristoleate, alpha-bisabolol, ethyl isopalmitate, 3-octadecenyl-phenol and the major component ethyl palmitate, were isolated from the roots. Structure elucidation of these secondary metabolites was accomplished by spectrometric analysis, including 1D and 2D NMR experiments such as ¹H, ¹H and ¹H,13C-COSY.

Constituíntes fenólicos polares de Schinus terebinthifolius Raddi (Anacardiaceae)

The EtOH extract from the leaves of Schinus terebinthifolius showed anti-radicalar potential in the DPPH test. It was partitioned between n-BuOH:H2O (1:1) and these two phases were also evaluated for anti-radicalar activity. The active n-BuOH phase was partitioned between EtOAc:H2O (1:1) and the active EtOAc phase was submitted to chromatographic procedures to afford five active phenolic compounds: ethyl gallate, methyl gallate, quercitrin, myricetrin and myricetin. The structures of these compounds were established by NMR spectral data analysis.

Estudo fitoquímico do decocto das folhas de Maytenus truncata Reissek e avaliação das atividades antinociceptiva, antiedematogênica e antiulcerogênica de extratos do decocto

The present paper describes the phytochemical investigation and biological activities of the chloroform, ethyl acetate and methanol extracts of leaf decocts of M. truncata Reiss (Celastraceae). Our studies afforded two flavonoid glycosides, quercetin-3-O-rhamnopyranosyl-O-glucopyranosyl- O-rhamnopyranosyl-O-galactopyranoside (1) and kampferol-3-O-rhamnopyranosyl-O-glucopyranosyl- O-rhamnopyranosyl-O-galactopyranoside (2) from the methanolic extract and dulcitol (3) from the ethyl acetate extract. Ethyl acetate and methanol extracts exhibited considerable antiulcerogenic and analgesic activities. The results of the phytochemical studies suggest that the healing activity of methanol extracts can be related to the presence of glycosyl flavonoids.

Correlation of anti-inflammatory activity with phenolic content in the leaves of syzygium cumini (l.) skeels (myrtaceae)

Phenolic contents of extracts of Syzygium cumini leaves, collected monthly over a one-year period, were quantitatively determined by the modified Folin-Ciocalteau method. Extracts and tannin-free fractions were assayed by their potential to inhibit mouse paw edema induced by C48/80. HPLC showed high molecular weight phenolic species and flavonoids in the active extracts and fractions. The highest total phenolic content corresponded to the most potent degree of inhibition and the flavonoids were supposed to be the main species responsible for the activity, given that the flavonoid-enriched ethyl-acetate fraction maintained its effect down to a dose of 0.01 mg/kg in a dose-response manner.

Determinação do coeficiente de atividade na diluição infinita (g¥) através da micro-extração em fase sólida (SPME)

In this study a new approach, solid phase micro extraction (SPME), is used in the evaluation of the infinite dilution activity coefficient of the solute in a given solvent. It is the purpose of the current work to demonstrate a different approach to obtain the data needed for studying the solution thermodynamics of binary liquid mixtures as well as for designing multi-component separations. The solutes investigated at the temperature 298.15 K were toluene, ethyl benzene and xylene in the solvent methanol.

Determination of cocaine in brazilian paper currency by capillary gas chromatography/mass spectrometry

The presence of illicit drugs such as cocaine and marijuana in US paper currency is very well demonstrated. However, there is no published study describing the presence of cocaine and/or other illicit drugs in Brazilian paper currency. In this study, Brazilian banknotes were collected from nine cities, extracted and analyzed by capillary gas chromatography/mass spectrometry, in order to investigate the presence of cocaine. Bills were extracted with deionized water followed by ethyl acetate. Results showed that 93% of the bills presented cocaine in a concentration range of 2.38-275.10 µg/bill.

Efeito da presença e concentração de compostos carbonílicos na qualidade de vinhos

Studies on identification of compounds that make up the aroma and flavor in wines involve research evaluating mainly the influence of terpenes, esters, lactones and alcohols upon these sensory characteristics. However, carbonylic compounds (CC) play an important role concerning the substances that impact aroma to these drinks. Their origin is reported to be linked to the grape's chemical composition, must fermentation or micro-oxidation occurring during storage in barrels. Some CCs, like E-ionone, E-damascenone, siryngaldehyde, can contribute a pleasant aroma and improve the wine quality whereas others are responsible for unpleasant characteristics (acetaldehyde, furfural, 5-hydroxy-methyl furfural, diacetil, E-non-2-enal, etc). A fraction of CCs present is associated with bisulfite ions in the form of hydroxyalkylsulfonic acids. Some of them are stable and play an important role in determining wine quality. The reaction involving the formation of this aduct commonly occurs with CCs of low molar mass, such as formaldehyde and acetaldehyde. The reaction involving CCs with more than three carbon atoms demands further studies.

Síntese de padrões cromatográficos e estabelecimento de método para dosagem da composição de ésteres de ácidos graxos presentes no biodiesel a partir do óleo de babaçu

Several alkyl esters were synthesized, purified, characterized by ¹H NMR and employed as standards for establishing chromatographic methods to monitor their formation in the synthesis of biodiesel. The efficiency of the chromatographic methods was confirmed with the products of enzymatic transesterification of babassu oil with different alcohols (C2 to C4), using Lipozyme as catalyst.

An easy and direct method for the synthesis of 1,2,4-triazole derivatives through carboxylic acids and hydrazinophthalazine

We have developed an easy method for the synthesis of thirteen compounds derived from 1,2,4-triazoles through a carboxylic acid and hydrazinophthalazine reaction, with a 75-85% yield mediated by the use of agents such as 1-ethyl-3-(3'-dimethylaminopropyl)-carbodiimide hydrochloride and 1-hydroxybenzotriazole. The operational simplicity of this method and the good yield of products make it valuable for the synthesis of new compounds with pharmacological activity.

Monoterpenos di-hidroxilados e hidróxi-nitrogenados 1,2 e 1,3 como ligantes quirais em reação de reformatsky assimétrica

This study describes the use of three (-)-alpha-pinene derivatives, one diol-1,2 [(-)-(1R, 2R, 3S, 5R)-2,6,6-trimethylbicyclo[3.1.1]heptane-2,3-diol 4] and two piridine-hydroxy derivatives [(+)-(1R,2S,3R,5S)-2,6,6-trimethyl-3-(2-pyridinylmethyl)bicyclo[3.1.1]heptan-3-ol 7 and (-)-(1R,2S,3R,5S)-2,6,6-trimethyl-3-[2-(2-pyridinyl) ethyl]bicyclo[3.1.1]heptan-3-ol 8]; one diol-1,3 [(-)-(1S,2R,5S)-2-(1-hydroxy-1-methylethyl)-5-methylcyclohexanol 5] derived from (+)-isopulegol 2 and one diol-1,3 [(+)-(1R,2R,5R)-2-(1-hydroxy-1-methylethyl)-5-methylcyclohexanol 6] derived from (+)-neo-isopulegol 3, as ligands in the asymmetric Reformatsky reaction. The best enantiomeric excess of beta-hydroxy ester obtained in the Reformatsky asymmetric reaction was 18% using ligand 6, and the chemical yield of the reactions was 65% on average.

Constituintes químicos de Ipomoea subincana Meisn. (Convolvulaceae)

The chloroform extract of aerial parts of Ipomoea subincana was submitted to different chromatographic procedures which afforded methyl caffeate, ethyl caffeate, methyl 3,4-dimethoxycinnamate, lupeol, alpha-amyrin, beta-amyrin, 3-beta-O-beta-D-glycopiranosyl-sitosterol, beta-sitosterol, stigmasterol, scopoletin, aromadendrane-4beta,10alpha-diol, n-docosyl-cis-p-coumarate and n-icosyl-trans-p-coumarate, vanilin, cinamic acid and vanillic acid. However, from the ethyl acetate extract besides quercetin and 3-O-beta-D-glycopiranosyl-quercetin were isolated methyl 4-O-E-feruloyl-5-O-E-caffeoyl-quinate, methyl 3,5-di-O-E-caffeoyl-quinate and methyl 4-O-E-caffeoyl-quinate. The structures of the compounds were established on the basis of spectral data.

Diastereosseletividade na redução de enonas bicíclicas com hidretos volumosos

Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride®) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring.

Rendimento térmico e emissões de contaminantes atmosféricos de gasolinas formuladas com etanol, MBTE e TAEE

The specific consumption and carbon monoxide (CO) and nitrogen oxide (NO) emissions from gasolines formulated with ethanol, methyl tert-butyl ether (MTBE) and tert-amyl ethyl ether (TAEE) were evaluated in the rich, stoichiometric and lean-burn regions during the operation of an Otto-cycle engine. The use of ethanol as an additive presented high specific consumption, while gasoline formulated with TAEE showed low specific consumption with the engine operating under lean-burn conditions. The ethers evaluated here presented a low percentage of CO in the rich-burn region when compared with ethanol.

Phytochemical study of Gypsophila trichotoma wend. (Caryophyllaceae)

Phytochemical studies of ethyl acetate extracts from the roots and aerial parts of Gypsophila trichotoma revealed the presence of stigmast-7-en-3-ol, stigmasta-7,22-dien-3-ol (spinasterol), ergost-7-en-3-ol, stigmasta-3,5dien7-one, β-sitosterol, 22,23-dihydrospinasterone, vitexin, orientin, homoorientin and hyperoside. The structures of the compounds were determined by GC/MS and HPLC analyses.