Is ortho-Cresol a Viable Lignocellulosic Blendstock? A Kinetic Study of Its Co-Oxidation within a Surrogate Fuel

The viability of the use of ortho-cresol as a bio-blendstock or antiknock additive from lignocellulosic biomass is assessed; Ignition delays of ortho-cresol within blends with iso-octane are measured with the ULille rapid compression machine, and compared with results from the literature; It is shown that ortho-cresol has a strong inhibiting effect on the reactivity towards ignition, most notably in the Negative Temperature Coefficient region; This effect is found to originate from competition with iso-octane on the OH radicals, where the reactivity of ortho-cresol with these radicals does not lead to radical chain-branching.

Development of Efficient and Selective Processes for the Synthesis of Commercially Important Chlorinated Phenols

para-Selective processes for the chlorination of phenols using sulphuryl chloride in the presence of various sulphur-containing catalysts have been successfully developed. Several chlorinated phenols, especially those derived by para-chlorination of phenol, ortho-cresol, meta-cresol, and meta-xylenol, are of significant commercial importance, but chlorination reactions of such phenols are not always as regioselective as would be desirable. We, therefore, undertook the challenge of developing suitable catalysts that might promote greater regioselectivity under conditions that might still be applicable for the commercial manufacture of products on a large scale. In this review, we chart our progress in this endeavour from early studies involving inorganic solids as potential catalysts, through the use of simple dialkyl sulphides, which were effective but unsuitable for commercial application, and through a variety of other types of sulphur compounds, to the eventual identification of particular poly(alkylene sulphide)s as very useful catalysts. When used in conjunction with a Lewis acid such as aluminium or ferric chloride as an activator, and with sulphuryl chloride as the reagent, quantitative yields of chlorophenols can be obtained with very high regioselectivity in the presence of tiny amounts of the polymeric sulphides, usually in solvent-free conditions (unless the phenol starting material is solid at temperatures even above about 50 °C). Notably, poly(alkylene sulphide)s containing longer spacer groups are particularly para-selective in the chlorination of m-cresol and m-xylenol, while, ones with shorter spacers are particularly para-selective in the chlorination of phenol, 2-chlorophenol, and o-cresol. Such chlorination processes result in some of the highest para/ortho ratios reported for the chlorination of phenols.

Detection of Anti-viral Drug Riamilovir and Herbicides in Aqueous Media by Using Pyrene-based Fluorescent Chemosensors

Two ethyleneglycol esters of 1-pyrene carboxylic acid were studied as chemosensors for the fluorescence “turn-off” detection of two nitro-containing analytes, such as antiviral drug Riamilovir (Triazavirin ®) and herbicidal agent dinitro-ortho-cresol (DNOC). In both cases the dramatic fluorescence quenching was observed with quenching constants as high as 3·104 M-1 and limits of detection (LOD) as low as 100 ppb.

Multiple SERS Detection of Phenol Derivatives in Tap Water

Phenol and some of its derivatives are products of the petrochemical industry. These compounds are characterized by their exceptional ability to persist in media and reach both food and water used by human beings. The consumption of these compounds has harmful effects on health, producing both acute and chronic effects—among the most prominent damages are teratogenicity, mutagenicity and carcinogenicity. Compounds such as phenol, ortho-cresol, and 1-napthol are listed by agencies such as the EPA. The aim of this work was the development of a rapid method for the simultaneous detection of these compounds in water samples. The method was based on the colorimetric reaction between phenol derivatives and Gibbs reagent, which forms indophenolates; using increased surface Raman spectroscopy together with statistical methods, SERS spectra were acquired, which were then analyzed. The developed method allows one to at least equalize the detection limits of the colorimetric method through UV–VIS spectroscopy and to discriminate among the three mixed phenols in at least binary aqueous samples. The major advantage of the method is the possibility of discriminating between phenol spectra quickly and easily.

Chemoenzymatic ortho-quinone methide formation

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

Chemoenzymatic ortho-quinone methide formation

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.

Biocatalyst-Initiated Ortho-Quinone Methide Formation and Derivatization

Generation of reactive intermediates and interception of these fleeting species in a cascade is a common strategy employed by Nature. However, formation of these species under mild conditions using traditional synthetic techniques can present a challenge. Here, we demonstrate the utility of biocatalysis in generating ortho-quinone methide intermediates under aqueous conditions and at reduced temperatures. Specifically, we applied an α-ketoglutarate-dependent non-heme iron enzyme, CitB, in the selective modification of benzylic C–H bonds of ortho-cresol substrates to afford a benzylic alcohol product which, under the reaction conditions, is in equilibrium with the corresponding ortho-quinone methide. Interception of the ortho-quinone methide by a nucleophile or a dienophile allows for one-pot conversion of benzylic C–H bonds into C–C, C–N, C–O, and C–S bonds in a chemoenzymatic cascade.