Calculations of the molecular interactions in 1,3-dibromo-2,4,6-trimethyl-benzene: Which methyl groups are quasi-free rotors in the crystal?

Hydrogenated dibromomesitylene (DBMH) is one of the few molecules in which a methyl group is a quasi-free rotor in the crystal state. DFT calculations –using Born-Oppenheimer approximation (BOa)- indicate that...

Concentrations of Volatile Organic Compounds in the Megacity of São Paulo in 2006 and 2011/2012 - A Comparative Study

The focus of this study was to measure the Volatile Organic Compounds (VOCs) concentrations in the megacity – São Paulo Metropolitan Area (SPMA). The measurements analyzed in this study included 78 hydrocarbon (HC) samples collected during 2006, and 66 samples of HC, 62 of aldehydes and 42 of ethanol collected during 2011-2012. The observational results showed that the consumption of ethanol, gasoline and diesel from 2006 to 2012 increased by 64 %, 23 % and 25 %, respectively, with substantial changes in the atmospheric composition. The 10 most abundant VOCs in the atmosphere found during 2011/2012 at CETESB IPEN/USP air quality monitoring station were ethanol, acetaldehyde, formaldehyde, acetone, propane, ethene, ethane, butane, 1-ethyl-4-methyl benzene, and 1,2,4-trimethyl benzene. During the 2006 campaign, alkanes represented 54.8 % of the total HC concentration, alkenes 29.2 %, aromatics 13.6 %, and alkadienes 2.4 %. On the other hand, during the 2011-2012 campaign, aldehydes represented 35.3 % of the VOCs, ethanol 22.6 %, aromatics 15.5 %, alkanes 13.5 %, acetone 6.8 %, alkenes 6.0 %, and alkadienes with less than 0.1 %. An increase in VOCs concentrations in the SPMA atmosphere from 2006 to 2012, such as aldehydes and aromatics (which are important ozone precursors) was measured.

Evaluation of the Chemical Composition of Gas and Particle Phase Products of Aromatic Oxidation

Aromatic volatile organic compounds (VOC) are key anthropogenic pollutants emitted to the atmosphere and are important for both ozone and secondary organic aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation that can lead to the formation of highly oxidised products. In this study we evaluate the gas and particle phase ions formed during the hydroxyl radical oxidation of substituted C9-aromatic isomers (1,3,5-trimethyl benzene, 1,2,4-trimethyl benzene, propyl benzene and isopropyl benzene) and a substituted polyaromatic hydrocarbon (1-methyl naphthalene) under low and medium NOx conditions. The majority of product signal in both gas and particle phases comes from ions which are common to all precursors, though signal distributions are distinct for different VOCs. Gas and particle phase composition are distinct from one another, and comparison with the near explicit gas phase Master Chemical Mechanism (MCMv3.3.1) highlights a range of missing highly oxidised products in the pathways. In the particle phase, the bulk of product signal from all precursors comes from ring scission ions, many of which have undergone further oxidation to form HOMs. Under perturbation of OH oxidation with increased NOx, the contribution of HOM ion signals to the particle phase signal remains elevated for more substituted aromatic precursors. Up to 25 % of product signal comes from ring-retaining ions including highly oxygenated organic molecules (HOMs); this is most important for the more substituted aromatics. Unique products are a minor component in these systems, and many of the dominant ions have ion formulae concurrent with other systems, highlighting the challenges in utilising marker ions for SOA.

Methylene: The Linker of Two Aromatic Iminium Salts

A straightforward synthesis of aromatic iminium salts has been developed by coupling 2-Azido-1,3,5-trimethyl benzene with 1,3-ditert-butylimidazolium tetrafluoroborate in basic conditions, followed by treatment with dichloromethane or iodomethane. Herein, we report the synthetic procedure and full characterization data, including X-ray structure analysis, of the expected bis(triazenyl)methane adduct 5. Moreover, we have discovered what constitutes a double carbon-chlorine bond activation.

Isolation, Identification and the Abilities of Fungi Associated with Agarwood from Bangka Belitung Island to Induce Agarwood Compounds

Agarwood is one of the non-timber forest products that have high economic value. Agarwood is widely used to make incense, perfume and other products. Sapwood on agarwood is a group of secondary metabolites of agarwood plants that form a lump and have a certain color and aroma. The fragrant aroma of sapwood on agarwood is formed due to pathogenic infection of the agarwood tree. Until now, most studies of fungi forming sapwood are only oriented to virulent pathogenic fungi in nature and have never been reported to form hypovirulent agarwood. This study aimed to evaluate the potential of fungi originating from sapwood on agarwood especially those that are hypovirulent in inducing sesquiterpene compounds. This study included exploration, isolation, identification, and induction of fungi associated with sapwood on agarwood from four districts in the Bangka Belitung Islands Province. Hypovirulence test in cucumber sprouts and sesquiterpene induction test on agarwood plantlets was conducted in the laboratory. Based on the isolation results, 48 fungal isolates associated with sapwood on agarwood were found: fungi of genus Fusarium, Trichoderma, Aspergillus, Penicillium, Curvularia, Peniophora, and six isolates were unidentified. Based on the hypovirulence test on cucumber sprouts, 46 isolates of the fungus 46 isolates were virulent and 2 isolates were hypovirulent (isolates 4A and 17A). The induction of sesquiterpene compounds on the agarwood plant was employed using 5 sample isolates consisting of 4 virulent isolates (2A, 7A, 18A, and 25A) and 1 hypovirulent isolate (Isolate 4A). The results showed that hypovirulent isolates were able to produce sesquiterpenes even in small amounts compared with virulent isolates. Isolates produced many sesquiterpene compounds were isolates 18A (Fusarium sp.). Sesquiterpene compounds formed were pinene, terpineol, patchouli alcohol, trimethyl-naphthalene, beta-caryophyllene, camphor, eugenol, trimethyl- benzene, phenanthrene, citronella, eucalyptol, 4-hydroxy-4-methyl-2-pentanone. In this study also found fungi associated with sapwood on agarwood which had never been reported by previous researchers, Peniophora sp. (isolate 25A).

Antimicrobial Activity of Freshwater Cyanobacterium Westiellopsis prolifica

The acetone and hexane of Westiellopsis prolifica extracts were examine efficiency against patho-genic bacterial and fungal isolates by using two methods: agar well diffusion and turbidiometric (tube method) against three Gram positive bacteria"Staphylococcus aureus, Bacillus subtilis, and Streptococcus sp." and three Gram- negative bacteria" Shigella sp., Proteus sp. and Pseudomonas aeruginosa " in additions to two isolates of fungi "Aspergillus niger and Candida albicans". The re-sults showed that crude acetone extract for W. prolifica better than the haxane extract and more efficient on negative gram bacteria than positive gram bacteria. The results of the agar well diffusion method evaluated that W. Prolifica acetone extract has the highest antibacterial activities against Streptococcus sp., S. aureus and A.niger with an inhibition zone of (20) mm, and the inhibition diam-eter to other bacteria and fungi were between(15-10) mm.While tube method showed that the ace-tone extract exhibited the highest inhibition against A.niger and less inhibiting to C. albicans. Purifica-tion of the acetone extracts was made by silica gel column chromatography, and among the five groups extracts, Group 2 (Benzene 50ml) was selected and analyzed by GC-MS. The presence of main components identified in the extract as alcohols, acids, monoterpene eucalyptol, hydrocarbons (unidecane) aromaticslike, Para- Xylene and 1,2,3 trimethyl benzene, Phytol, n-Hexadecanoic acid, etc. These purified active compounds take part into broad horizons in the fields of biotechnology and pharmacy.