Rodinei Augusti

Application of Fenton’s reagent to regenerate activated carbon saturated with organochloro compounds

In this work Fentons reagent was used to treat activated carbon saturated with organochloro compounds for the oxidation of the adsorbed contaminants and the regeneration of the carbon adsorbent. Activated carbon containing adsorbed chlorinated model substrates such as chlorobenzene, tetrachloroethylene, chloroform or 1,2-dichloropropane was treated with Fentons reagent at room temperature resulting in a rapid consumption of the organochloro compounds. Thermogravimetric, infrared, BET surface area and MIMS adsorption studies showed that Fentons treatment has no significant effect on the physico-chemical properties of the activated carbon. The used carbon adsorbents can be efficiently regenerated and recycled with no loss of its adsorption capacity even after five consecutive treatments with Fentons reagent.

Organic Reactions of Ionic Intermediates Promoted by Atmospheric‐Pressure Thermal Activation

Interest in “green chemistry” has made the development of environmentally benign alternatives to organic solvents and conventional acid catalysts an active area of investigation. The replacement of organic solvents with recyclable ionic liquids and supercritical carbon dioxide, as well as the replacement of acid catalysts by supercritical water (400 8C, 200 bar) and near-critical water (275 8C, 60 bar), has already been demonstrated in organic synthesis. These developments, and accompanying studies of reaction mechanisms under unusual conditions, have increased the interest in nontraditional ways of carrying out reactions and exploring their mechanisms. Several such approaches are based on mass spectrometry, the best established of which is the use of chemical ionization and gas-phase Brønsted acid/base reactions to generate the ions of interest. Mass spectrometry can be employed to study the reactivity of organic reactants by using electrospray ionization (ESI) to generate ionic reagents under ambient pressure. ESI has been widely used to ionize organic and biological samples, thus allowing compounds to be protonated at their basic sites or deprotonated at their acidic sites. The protonation process with ESI is known to occur even when the analyte is dissolved in pure protic solvents, such as water or methanol, without any added acids or bases. The dissociation equilibrium H2OQH + + OH and the electrochemical reaction 2H2OQ4H + + O2 + 4e [23] are proton sources. This phenomenon prompted us to use ESI as a mild alternative to acid catalysis for generating ionic intermediates in organic reactions. As the protonated analyte ions (potential reaction intermediates in solution-phase reactions) generated by ESI are thermalized by numerous collisions with third body gaseous molecules at atmospheric pressure, they must be activated to undergo reaction. We recently developed an atmospheric-pressure thermal activation method based on a heated coiled tube, which can be used, among other things, for protein/peptide ion dissociation and hence as an aid in sequencing. Herein we have employed this atmosphericpressure activation method to promote reactions of organic ions generated by electrosonic spray ionization (ESSI), a variant form of ESI. By using this strategy, several organic reactions, including the Fischer indole synthesis, the Borsche– Drechsel cyclization, and the pinacol rearrangement, have been successfully performed under mild conditions (Scheme 1 and Figure 1a).

Platinum/tin catalyzed hydroformylation of naturally occurring monoterpenes

Abstract (−)-β-Pinene, R -(+)-limonene, and (−)-camphene have been hydroformylated regiospecifically to give exclusively the linear isomers of corresponding aldehydes. The following systems were used as catalysts: PtCl 2 (PPh 3 ) 2 /SnCl 2 /PPh 3 , and PtCl 2 (diphosphine)/SnCl 2 /PPh 3 whose diphosphines were 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane and 1,4-bis(diphenylphosphino) butane. The hydroformylation of β-pinene yields trans- 10-formylpinane with a 98% diastereoisomeric excess (d.e.), while limonene and camphene give the diastereoisomers of the corresponding aldehydes in approximately equal amounts (d.e. of ca. 10 and 15%, respectively). Differently from most of the rhodium and cobalt catalysts, the undesirable isomerization of β- to α-pinene is rather slow (1–5% based on reacted β-pinene). The primarily formed aldehyde of limonene undergoes the highly diasteroselective intramolecular cyclization (d.e. of virtually 100%) catalyzed by the platinum/tin active species yielding 4,8-dimethyl-bicyclo[3.3.1]non-7-en-2-ol. The effects of the catalyst composition and ligand nature on the product distribution have been studied. The use of PPh 3 as the only phosphorous-containing ligand, as well as the excess of SnCl 2 (Sn/Pt>1) promote the isomerizations of monoterpenes. The system with 1,3-bis(diphenylphosphino)propane causes excessive hydrogenation of the olefinic double bonds. Under optimized conditions, chemoselectivities for aldehyde formation of near 90% have been attained for all monoterpenes studied.

Photolysis and photocatalysis of ibuprofen in aqueous medium: characterization of by-products via liquid chromatography coupled to high-resolution mass spectrometry and assessment of their toxicities against Artemia Salina

The degradation of the pharmaceutical compound ibuprofen (IBP) in aqueous solution induced by direct photolysis (UV-A and UV-C radiation) and photocatalysis (TiO2 /UV-A and TiO2 /UV-C systems) was evaluated. Initially, we observed that whereas photocatalysis (both systems) and direct photolysis with UV-C radiation were able to cause an almost complete removal of IBP, the mineralization rates achieved for all the photodegradation processes were much smaller (the highest value being obtained for the TiO2 /UV-C system: 37.7%), even after an exposure time as long as 120 min. Chemical structures for the by-products formed under these oxidative conditions (11 of them were detected) were proposed based on the data from liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) analyses. Taking into account these results, an unprecedented route for the photodegradation of IBP could thus be proposed. Moreover, a fortunate result was achieved herein: tests against Artemia salina showed that the degradation products had no higher ecotoxicities than IBP, which possibly indicates that the photocatalytic (TiO2 /UV-A and TiO2 /UV-C systems) and photolytic (UV-C radiation) processes can be conveniently employed to deplete IBP in aqueous media.

Quantitative determination of the enantiomeric composition of thalidomide solutions by electrospray ionization tandem mass spectrometry

Rapid and simple chiral analysis of thalidomide solutions is demonstrated by using electrospray ionization tandem mass spectrometry and analysis of cluster ion dissociation by the kinetic method. Average deviations of 1% between the actual and experimental enantiomeric compositions are observed.

Determination of volatile compounds in Brazilian distilled cachaça by using comprehensive two-dimensional gas chromatography and effects of production pathways.

Comprehensive two-dimensional gas chromatography (GCxGC) was applied to the study of cachaça production. Effects of bidistillation, and the use of charcoal filtration in the production of artisan cachaça, as well as the effects of multi-distillation on volatile products in commercial cachaça were investigated. Volatile compounds were collected and concentrated onto a polyacrylate solid-phase microextraction fibre, and analyzed using GCxGC on a non-polar (BPX5)-polar (BP20) column set. More than 100 compounds, comprising various homologous series were tentatively identified using MS library matching and comparison with retention indices. Phthalate organic contamination following the use of ion exchange resin for removal of copper ion was evident. Charcoal successfully removes this contamination product. Prediction of compounds within particular homologous series aids component identification.

Convenient one-pot synthesis of 4,8-dimethyl-bicyclo[3.3.1]non-7-en-2-ol via platinum/tin catalyzed hydroformylation/cyclization of limonene

Abstract Limonene ( 1 ) was converted in one step into two diasteroisomers of 4,8-dimethyl-bicyclo[3.3.1]non-7-en-2-ol ( 2 ), useful as perfumes, employing PtCl 2 (PPh 3 ) 2 /PPh 3 /SnCl 2 and PtCl 2 (diphosphine)/PPh 3 /SnCl 2 systems as bifunctional catalysts whose diphosphines were 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane (dppb). In the presence of the PtCl 2 (dppb)/PPh 3 /SnCl 2 system, which was found to be the most promising combination, the selectivity for 2 reached the value of 82% at 95% conversion of 1 .

Palladium/tin catalyzed alkoxycarbonylation of naturally occurring bicyclic monoterpenes

Abstract The alkoxycarbonylation of camphene and β -pinene has been studied. The following systems have been used as catalysts: PdCl 2 (PPh 3 ) 2 /SnCl 2 /PPh 3 and PdCl 2 (diphosphine)/SnCl 2 /PPh 3 whose diphosphines were 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane and 1,4-bis(diphenylphosphino)butane. It was observed that several concurrent transformations of monoterpenes occur in the reaction solutions. To find the optimum conditions for alkoxycarbonylation the effect of the reaction variables on the product distribution has been investigated. The reaction of β -pinene exclusively yields the products of the Lewis acid catalyzed skeletal rearrangement accompanied by a nucleophilic addition of chloride and methoxy groups. No products of carbon monoxide incorporation were observed. Camphene was converted to the corresponding linear ester composed of approximately equal amounts of exo and endo isomers with a selectivity of 90% and virtually 100% regioselectivity (linear/branched esters) using a PdCl 2 (PPh 3 ) 2 /SnCl 2 /PPh 3 system as a catalyst. Methyl bornyl ether was the only major by-product. SnCl 2 and PdCl 2 (PPh 3 ) 2 exhibited a strong synergetic effect on the camphene alkoxycarbonylation. PdCl 2 (PPh 3 ) 2 alone showed a very low catalytic activity promoting the predominant formation of the thermodynamically more stable exo isomer (the exo/endo ratio is approximately 2:1).

Evaluation of the composition of street cocaine seized in two regions of Brazil

This work evaluates cocaine purity and the concentration ranges of adulterants and inorganic constituents for 31 street cocaine samples seized in two different regions of Brazil from July 2008 to May 2010. Cocaine and adulterants, such as caffeine, lidocaine and benzocaine, were quantified by Gas chromatography-mass spectrometry (GC-MS), and the inorganic constituents were determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and ion chromatography (IC). The cocaine concentrations in the samples seized in the Amazonas state (AM samples) ranged from 154 to 978mgg(-1), and these samples did not contain any of the adulterants studied. The cocaine concentrations in the samples seized in the Minas Gerais state (MG samples) ranged from 63.9 to 753mgg(-1). Caffeine was the main adulterant found in 76% of the MG samples, ranging in concentration from 5.5 to 645.3mgg(-1). Lidocaine was found in 66.7% of the MG samples, with concentrations ranging from 16.3 to 576.7mgg(-1). Benzocaine was found in only one MG sample, at a concentration of 84.8mgg(-1). Fourteen elements were identified by ICP-OES, and a wide variation was observed in the concentrations of Ca, Mg, Na, P, Al, Fe, Mn and Zn. Pearson Product-moment Correlations between the analytes allowed the constituents to be associated with the chemicals used in the manufacturing of cocaine and with some common diluents. The study of the purity of cocaine and the presence and concentration of adulterants and inorganic constituents is important because the latter can have deleterious effects on health.

Recognition and Resolution of Isomeric Alkyl Anilines by Mass Spectrometry

Two MS techniques have been used to recognize and resolve a representative isomeric pair of N-alkyl and ring-alkyl substituted anilines. The first technique (1) uses MS/MS to perform ion/molecule reactions of structurally-diagnostic fragment ions (SDFI) whereas the second (2) uses traveling wave ion mobility spectrometry (TWIMS) of the pair of protonated molecules followed by on-line collision-induced dissociation (CID), that is, MS/TWIMS-CID/MS. Isomeric C7H7N+ ions of m/z 106 (1′ from 4-butylaniline and 2 from N-butylaniline) are formed as abundant fragments by 70 eV EI of the anilines, and found to function as suitable SDFI. Ions 1′ and 2 display nearly identical unimolecular dissociation chemistry, but contrasting bimolecular reactivity with ethyl vinyl ether, isoprene, acrolein, and 2-methyl-1,3-dioxolane. Ion 2 forms adducts to a large extent whereas 1′ is nearly inert towards all reactants tested. The intact protonated anilines are readily resolved and recognized by MS/TWIMS-CID/MS in a SYNAPT mass spectrometer (Waters Corporation, Manchester, UK). The protonated N-butyl aniline (the more compact isomer) displays shorter drift time and higher lability towards CID than its 4-butyl isomer. The general application of SDFI 1′ and 2 and other homologous and analogous ions and MS/TWIMS-CID/MS for absolute recognition and resolution of isomeric families of N-alkyl and ring-alkyl mono-substituted anilines and analogues is discussed.