One-pot synthesis of α-bromoacetals of ketones from secondary alcohols and 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) in ethylene glycol

<p>α-Bromoacetals of ketones were prepared from various secondary alcohols with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) and ethylene glycol through oxidation, bromination, and acetalization in one pot without the use of other catalysts under mild conditions. The effects of DBDMH, the solvent, and <i>N</i>-bromosuccinimide on the reaction were investigated. Under the optimal conditions, most α-bromoacetals of ketones were obtain in 90–98% yields.</p

Enhanced Selectivity of Phenol Hydrogenation in Low-Pressure CO₂ over Supported Pd Catalysts

Selective hydrogenation of phenol to cyclohexanone is an important process in both chemical industry and renewable feedstock processing. However, direct hydrogenation of phenol to cyclohexanone under mild conditions over catalysts with high reactivity, selectivity, and facile preparation is still a challenge. In the present study, we report that 99% conversion and 99% selectivity can be achieved over as-prepared Pd/γ-Al₂O₃ catalyst under the medium of low-pressure CO₂ (0.05–0.2 MPa) and H₂O at 373 K. According to experiment results, ab initio calculations and in situ high-pressure FTIR measurements indicated enhanced selectivity of cyclohexanone in low-pressure CO₂; this result originated from the molecular interaction between cyclohexanone and CO₂ and can prevent the further hydrogenation of cyclohexanone. Notably, enhancement of selectivity to cyclohexanone in low-pressure CO₂ was also achieved using commercial Pd/γ-Al₂O₃ and Pd/C catalysts