- METHOD FOR PREPARING P-HYDROXYMANDELIC COMPOUNDS IN STIRRED REACTORS
-
The process allows the preparation of a p-hydroxymandelic compound, comprising at least one step of condensation of at least one aromatic compound bearing at least one hydroxyl group and whose para position is free, with glyoxylic acid, the condensation reaction being performed in at least one reactor equipped with at least one mixing means, the specific mixing power being between 0.1 kW/m3 and 15 kW/m3. In addition, the invention also relates to a process for preparing a 4-hydroxyaromatic aldehyde by oxidation of this p-hydroxymandelic compound.
- -
-
-
- PROCESS FOR PRODUCING A T-BUTYL PHENOL FROM A C4 RAFFINATE STREAM
-
This invention relates to processes for producing various t-butyl phenols, such as 2,6-di-tert-butyl phenol and ortho-tert-butyl phenol, by selectively reacting phenol or a substituted phenol with an isobutylene-containing C4 raffinate stream. The 2,6-di-tert-butyl phenol and ortho-tert-butyl phenol can be transalkylated to form other tert-butyl phenols, such as para-tert-butyl phenol, 2,4-di-tert-butyl phenol.
- -
-
Page/Page column 11
(2011/06/25)
-
- Competitive degradation and detoxification of carbamate insecticides by membrane anodic fenton treatment
-
The competitive degradation of six carbamate insecticides by membrane anodic Fenton treatment (AFT), a new Fenton treatment technology, was carried out in this study. The carbamates studied were dioxacarb, carbaryl, fenobucarb, promecarb, bendiocarb, and carbofuran. The results indicate that AFT can effectively degrade these insecticides in both single component and multicomponent systems. The carbamates compete for hydroxyl radicals, and their kinetics obey the previously developed AFT kinetic model quite well. Hydroxyl radical reaction rate constants were obtained, and they decrease in the following order: dioxacarb ≈ carbaryl > fenobucarb > promecarb > bendiocarb > carbofuran. The AFT is shown to have higher treatment efficiency at higher temperature. Degradation products of the carbamates were determined by gas chromatography/mass spectrometry, and it appears that degradation can be initiated by hydroxyl radical attack at different sites in the molecule, depending on the individual structure of the compound. Substituted phenols are the commonly seen degradation products. The AFT treatment can efficiently remove the chemical oxygen demand of the carbamate mixture, significantly increasing the biodegradability. Earthworm studies show that the AFT is also an effective detoxification process.
- Wang, Qiquan,Lemley, Ann T.
-
p. 5382 - 5390
(2007/10/03)
-
- Process for functionalising a phenolic compound carrying an electron-donating group
-
The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
- -
-
-
- A fluorescence detection scheme for capillary electrophoresis of N- methylcarbamates with on-column thermal decomposition and derivatization
-
This paper describes a fluorescence detection method for N- methylcarbamate (NMC) pesticides in micellar electrokinetic chromatography (MEKC) separation. Fulfillment of the fluorescence detection hinged on the discovery that quaternary ammonium surfactants (particularly cetyltrimethylammonium bromide, CTAB), besides serving as hydrophobic pseudophases in MEKC, are also capable of catalyzing the thermal decomposition of NMCs to liberate methylamine. Thus, a multifunctional MEKC medium consisting of borate buffer, CTAB, and derivatizing components (o- phthaldialdehyde/2-mercaptoethanol) was formulated, which allowed first normal MEKC separation, subsequent thermal decomposition, and finally in situ derivatization of NMCs. With careful optimization of the operation conditions, fluorescence detection of 10 NMC compounds was achieved, with column efficiencies typically higher than 50 000 and detection limits better than 0.5 ppm. The present work represents an unprecedented effort in capillary electrophoresis (CE), in which an intact capillary was consecutively utilized as chambers for separation, decomposition, derivatization, and detection, without involving any interfacing features. The success in the implementation of such a detection system resulted in strikingly simple instrumentation as compared with the traditional postcolumn fluorescence determination of NMCs by reversed-phase HPLC. Similar protocols should be workable in the determination of a wide range of pesticides and pharmaceuticals in CE formats.
- Wu, Yuan Sheng,Lee, Hian Kee,Li
-
p. 1441 - 1447
(2007/10/03)
-
- O-alkylation of phenolic compounds via rare earth orthophosphate catalysts
-
Carbocyclic/aliphatic ethers, for example anisole, quaicol, guaethol, p-methoxyphenol and ethylene dioxybenzene, are selectively prepared, in good yield, by reacting a phenolic compound, for example a phenol, hydroquinone, pyrocatechin, naphthol, or the like, with an alcohol, for example methanol, ethanol, isopropanol, ethylene glycol, etc., in gaseous phase, in the presence of a catalytically effective amount of a trivalent rare earth metal orthophosphate, for example a lanthanum, cerium or samarium orthophosphate, optionally doped with an alkali or alkaline earth metal, preferably cesium.
- -
-
-
- Metal cation-exchanged montmorillonite (Mn+-mont)-catalysed aromatic alkylation with aldehydes and ketones
-
The alkylation of aromatic compounds with aldehydes and ketones in the presence of a variety of metal cation-exchanged montmorillonites (Mn+-mont; Mn+ = Zr4+, Al3+, Fe3+, Zn2+, H+, Na+) has been investigated. Al3+- and Zr4+-Monts are revealed to be effective as catalysts, while no reaction takes place with Na+-mont. Al3+-Mont-catalysed alkylation of phenol with several aldehydes produces mainly or almost solely the corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) in good yields, while that with several ketones affords selectively the corresponding alkylphenols in moderate to good yields. The alkylation always occurs at the carbonyl carbon without any skeletal rearrangement and the kind of products depends much on the steric hindrance of an electrophilic intermediary carbocation. The alkylation of anisole, veratrole and p-cresol proceeds well, while that of toluene, benzene, chlorobenzene and nitrobenzene scarcely occurs.
- Tateiwa, Jun-Ichi,Hayama, Ei,Nishimura, Takahiro,Uemura, Sakae
-
p. 1923 - 1928
(2007/10/03)
-
- Acidity effect in the regiochemical control of the alkylation of phenol with alkenes
-
Treatment of 1:1 mixtures of phenol and linear alkenes in the presence of an acidic promoter in CHCl3 at room temperature results in ortho-regioselective monoalkylation producing sec-alkylphenols in 48-60% yield. In similar reactions, branched alkenes lead exclusively to the corresponding para-tert-alkylphenols in 80-85% yield. Addition of increasing amounts of potassium phenolate to the reacting system reduces the protic acidity and promotes ortho-regioselective tert-alkylation. These results are tentatively explained in terms of competition of 'H-bond-template' and 'charge-controlled' mechanisms.
- Sartori, Giovanni,Bigi, Franca,Maggi, Raimondo,Arienti, Attilio
-
p. 257 - 260
(2007/10/03)
-
- Rearrangement Alkyl Phenyl Ethers to Alkylphenols in the Presence of Cation-exchanged Montmorillonite (Mn+-Mont)
-
The rearrangement of alkyl phenyl ethers such as 4-phenoxybutan-2-one 1, 1-phenoxybutane 2a, 2-phenoxybutane 2b, 2-methyl-2-phenoxypropane 2c and phenoxycyclohexane 2d have been investigated in the presence of cation-exchanged montmorilonite (Mn+-mont; Mn+ = Zr4+, Al3+, Fe3+ and Zn2+).The ether 1 rearranged to 4-(4-hydroxyphenyl)butan-2-one 3 (raspberry ketone), the odour source of rasprerry, in 16-34percent GLC yield, where Zn2+-mont was the most effective catalyst.Similarly, other ethers 2a-d rearranged to the corresponding alkylphenols in up to 75percent isolated yield with good product selectivity, Al3+-mont being the catalyst of choice.Al3+-Mont was regenerated and resulted in the rearrangement of 2b, 2c and 2d.
- Tateiwa, Jun-ichi,Nishimura, Takahiro,Horiuchi, Hiroki,Uemura, Sakae
-
p. 3367 - 3372
(2007/10/02)
-
- Equilibria for the isomerization of (secondary-alkyl)phenols and cyclohexylphenols
-
Equilibria of a series of isomerizations and trans-alkylations of alkylphenols have been investigated in the liquid phase over a wide range of temperatures.Equilibria of isomerizations connected with the displacement of a substituent on a benzene nucleus were studied for secondary-butyl, -amyl, -hexyl, and cyclohexyl-phenols, and di-(secondary-butyl)phenols.Equilibria of positional isomerization connected with the displacement of an oxyphenyl radical in an alkyl chain were investigated for oxyphenyl-pentanes, -hexanes, -octanes, and -decanes.Trans-alkylation was investigated for di- and tri-(secondary-butyl)phenols.Values of ΔrH0m and ΔrS0m were found for all investigated reactions.An analysis was made of the thermodynamic quantities for the reactions.Enthalpies of formation of isopropylphenols (IPP) in the gaseous state were calculated.The values of ΔfH0m/(kJ * mol-1) were found at 298.15 K: o-IPP, -(175.3 +/- 2.4); p-IPP, -(175.3 +/- 2.4); m-IPP, -(175.3 +/-2.4); 2,4-di-IPP, -(254.1 +/- 2.8); 2,5-di-IPP, -(254.1 +/- 2.8); 2,6-di-IPP, -(254.1 +/- 2.8); 3,5-di-IPP, -(254.1 +/- 2.8); 2,4,6-tri-IPP, -(333.0 +/- 3.1).
- Nesterova, T. N.,Pimerzin, A. A.,Rozhnov, A. M.,Karlina, T. N.
-
p. 385 - 396
(2007/10/02)
-
- Preparation of diphenolics
-
A process for the production of diphenolic compounds having a divalent bridge. A first disubstituted phenol is reacted with an aldehyde in the presence of a secondary amine and excess alcohol to form an ether intermediate. The ether intermediate is reacted with a phenol having an open ortho or para position to form a diphenolic.
- -
-
-
- Preparation of substituted phenols
-
Substituted phenols of the general formula I STR1 where R1, R2, R3, R4 and R5 are each hydrogen or an aliphatic or aromatic hydrocarbon radical, are prepared by dehydrogenating a cyclic alcohol of the general formula II STR2 or a cyclic ketone of the general formula III STR3 where one of the broken lines can be an additional C-C bond, in the gas phase at from 150° to 380° C. over a supported noble metal catalyst, by a process in which the dehydrogenation catalyst used is palladium or platinum on an aluminum spinel carrier, in particular an aluminum spinel which has a BET specific surface area of from 5 to 150 m2 /g or, for the dehydrogenation of cyclohexenones, preferably from 10 to 50 m2 /g. Particularly suitable aluminum spinels are those which, in addition to aluminum, contain magnesium, zinc, cobalt or nickel. In the novel process, substituted phenols are obtained in high yields and selectivities, and the catalyst has an extremely long life without a significant decrease in activity.
- -
-
-
- Phenol transalkylation process
-
Phenols having an unsubstituted ortho position are transalkylated in the ortho position by mixing them with an ortho-alpha-branched alkylphenol (e.g., 2,6-di-sec-butylphenol) and an aluminum phenoxide catalyst and heating the mixture to 100°-350°C., preferably in a closed system and in the presence of olefin corresponding in structure to the ortho-alpha-branched alkyl group.
- -
-
-
