Crystal structure of pseudoguainolide

The lactone ring in the title molecule, C15H22O3(systematic name: 3,4a,8-trimethyldodecahydroazuleno[6,5-b]furan-2,5-dione), assumes an envelope conformation with the methine C atom adjacent to the the methine C atom carrying the methyl substituent being the flap atom. The other five-membered ring adopts a twisted conformation with the twist being about the methine–methylene C—C bond. The seven-membered ring is based on a twisted boat conformation. No specific interactions are noted in the the crystal packing.

Crystal structure of 7,7-dimethyl-6-methylidenetricyclo[6.2.1.01,5]undecane-2-carboxylic acid

In the title compound, C₁₅H₂₂O₂, both five-membered rings display an envelope conformation whereas the six-membered ring displays a chair conformation. In the crystal, pairs of O—H⋯O hydrogen bonds between carb­oxy­lic groups link mol­ecules, related by a twofold rotation axis, into supra­molecular dimers.

Molybdenum blue nano-rings: an effective catalyst for the partial oxidation of cyclohexane

Molybdenum blue (MB), a multivalent molybdenum oxide with a nano-ring morphology is well-known in analytical chemistry but, to date it has been largely ignored in other applications.

Prevalence and public health implications of state laws that criminalize potential HIV exposure in the United States

For the past three decades, legislative approaches to prevent HIV transmission have been used at the national, state, and local levels. One punitive legislative approach has been enactment of laws that criminalize behaviors associated with HIV exposure (HIV-specific criminal laws). In the USA, HIV-specific criminal laws have largely been shaped by state laws. These laws impose criminal penalties on persons who know they have HIV and subsequently engage in certain behaviors, most commonly sexual activity without prior disclosure of HIV-positive serostatus. These laws have been subject to intense public debate. Using public health law research methods, data from the legal database WestlawNext© were analyzed to describe the prevalence and characteristics of laws that criminalize potential HIV exposure in the 50 states (plus the District of Columbia) and to examine the implications of these laws for public health practice. The first state laws were enacted in 1986; as of 2011 a total of 67 laws had been enacted in 33 states. By 1995, nearly two-thirds of all laws had been enacted; by 2000, 85 % of laws had been enacted; and since 2000, an additional 10 laws have been enacted. Twenty-four states require persons who are aware that they have HIV to disclose their status to sexual partners and 14 states require disclosure to needle-sharing partners. Twenty-five states criminalize one or more behaviors that pose a low or negligible risk for HIV transmission. Nearly two-thirds of states in the USA have legislation that criminalizes potential HIV exposure. Many of these laws criminalize behaviors that pose low or negligible risk for HIV transmission. The majority of laws were passed before studies showed that antiretroviral therapy (ART) reduces HIV transmission risk and most laws do not account for HIV prevention measures that reduce transmission risk, such as condom use, ART, or pre-exposure prophylaxis. States with HIV-specific criminal laws are encouraged to use the findings of this paper to re-examine those laws, assess the laws' alignment with current evidence regarding HIV transmission risk, and consider whether the laws are the best vehicle to achieve their intended purposes.

Base-free oxidation of glycerol using titania-supported trimetallic Au–Pd–Pt nanoparticles

Base-free selective oxidation of glycerol has been investigated using trimetallic Au–Pd–Pt nanoparticles supported on titania and their corresponding bimetallic catalysts. Catalysts were prepared by the sol-immobilization method and characterized by means of TEM, UV/Vis spectroscopy, diffuse reflectance infrared fourier transform spectroscopy, X-ray photoelectron spectroscopy, and microwave plasma–atomic emission spectroscopy. It was found that of the bimetallic catalysts, Pd–Pt/TiO2 was the most active with high selectivity to C3 products. The addition of Au to this catalyst to form the trimetallic Au–Pd–Pt/TiO2, resulted in an increase in activity relative to Pd–Pt/TiO2. The turnover frequency increased from 210 h(−1) with the Pd–Pt/TiO2 catalyst to378 h(−1) for the trimetallic Au–Pd–Pt/TiO2 catalyst with retention of selectivity towards C3 products.

The benzaldehyde oxidation paradox explained by the interception of peroxy radical by benzyl alcohol

Benzaldehyde readily undergoes autoxidation to form benzoic acid on exposure to air at room temperature. Yet it can be formed in high yield from, for example, benzyl alcohol by oxidation using a variety of procedures and catalysts. Here we report the evidence to resolve this apparent paradox. It is confirmed that benzyl alcohol (and a number of other alcohols), even at low concentrations in benzaldehyde, inhibits the autoxidation. Furthermore we report on the structural features required for inhibition. Electron paramagnetic resonance spin trapping experiments demonstrate that benzyl alcohol intercepts, by hydrogen atom transfer, the benzoylperoxy radicals that play a key role in benzaldehyde autoxidation. A similar inhibition effect has also been observed for the aliphatic octanal/1-octanol system.

Solvent-free aerobic oxidation of alcohols using supported gold palladium nanoalloys prepared by a modified impregnation method

The synthesis of stable, supported, bimetallic nanoalloys with controlled size, morphology and composition for selective alcohol oxidation.

Initiator-free hydrocarbon oxidation using supported gold nanoparticles

In the catalytic oxidation of cycloalkenes and linear internal alkenes using oxygen radical initiators are not required if the stabilisers are removed prior to reaction.

Gold-nanoparticle-based catalysts for the oxidative esterification of 1,4-butanediol into dimethyl succinate

The oxidation of 1,4-butanediol and butyrolactone have been investigated by using supported gold, palladium and gold-palladium nanoparticles. The products of such reactions are valuable chemical intermediates and, for example, can present a viable pathway for the sustainable production of polymers. If both gold and palladium were present, a significant synergistic effect on the selective formation of dimethyl succinate was observed. The support played a significant role in the reaction, with magnesium hydroxide leading to the highest yield of dimethyl succinate. Based on structural characterisation of the fresh and used catalysts, it was determined that small gold-palladium nanoalloys supported on a basic Mg(OH)2 support provided the best catalysts for this reaction.