Phenols hydroxy benzoates

Polysaccharide-based CSPs also exhibit a chiral recognition for alcohols and a large number of resolutions have been reported. Chiral alcohols can usually be directly resolved with hexane containing a small amount of an alcohol as the eluent. For aliphatic alcohols, which cannot be directly resolved, their resolution is often efficiently attained as phenylcarbamate or benzoate derivatives on OD (Figure 17).85 For example, 2-butanol and 2-pentanol are completely resolved with a very high selectivity on OD as their phenylcarbamates. The derivatization of alcohols to phenylcarbamates and benzoates can be easily achieved by the reaction with phenyl isocyanates and benzoyl chlorides, respectively. In most cases, the phenylcarbamates are better resolved than the benzoates. For chiral compounds bearing phenolic hydroxy groups, the addition of a small amount of an acid to an eluent is recommended to depress its dissociation. 

Prochlorperazine Edisylate Prochlorperazine edisylate is not compatible with sodium chloride solutions containing methyl hydroxybenzoate and propyl hydroxy-benzoate as preservatives, but is compatible with solutions containing benzyl alcohol. Prochlorperazine edisylate salts are incompatible with a number of drugs such as aminophylline, amphotericin, ampicillin sodium, some barbiturates, ben-zylpenicillin salts, calcium gluconate, cefmetazole sodium, cephalothin sodium, chloramphenicol sodium succinate, chlorothiazide sodium, chloramphenicol, morphine sulfate containing phenol, magnesium trisilicate mixture, sodium succinate, chlorothiazide sodium, dimenhydrinate, heparin sodium, hydrocortisone sodium succinate, midazolam hydrochloride, and some sulfonamides.166... 

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

The transformation of an equimolar mbcture of phenol (P) and of phenyl acetate (PA) (2.2M) was carried out in dodecane (2.3M) or in sulfolane (5.5M) solvents over 100 mg and 500 mg of H-BEA-10 and over 100 mg of H-BEA-70. 0-hydroxyacetophenone (o-HAP),p-hydroxyacetophenone (p-HAP), p-acetoxyacetophenone (p-AXAP) and phenol appear as primary products while bisphenol A and its mono and diacylated products as well as a low amount of hydroxy-benzoate of benzyle and traces of trimethylbenzene appear at high conversion ordy. 

How would you prepare the following compounds from the named starting material (a) l-methoxy-.Vnitrobcnzcne from ben-zenesulfonic acid (b) methyl 2-hydroxy benzoate from phenol (c) 2-bromo-4-methvlphcnol from toluene. 

These phenolic compounds are listed in Section 6, Acids in Section 6.1.10 / -Hydroxy-benzoates because of their exceptional acidic character. 

The bathochromic shift which occurs in the spectra of many phenolic compounds with change of pH may be used as the basis of a simple spectro-photometric assay (AE method) when they are present in complex formulations. A pre-requisite of the method is the absence of spectral changes of the other constituents under the same conditions. The method has been adapted by Elvidge and Peutrell for the determination of hexachloro-phane and other phenols (phenol, resorcinol, cresol and methyl hydroxy-benzoate) in various pharmaceutical products. 

Takahashi [12, 13] used gas liquid chromatography to determine BHA and BHT in breakfast cereals. He obtained quantitative recoveries of 20 to 30 ppm of the antioxidants added to cereals. To determine antioxidants and preservatives in soya sauce and other foods, Takemura [14] converted these compounds to trimethylsilyl derivatives and analysed the product by GC. The sample was shaken with the silation reagent (1 ml) for 30 seconds, then set aside for 5 minutes and 2 pi of the solution was analysed by GC on, for example 20% of SE-31 silicone on Celite 545 at 200 °C with helium as carrier gas (22 ml/min) and hexane as internal standard. The method was applied to 15 preservatives and 7 antioxidants well-separated peaks were obtained for 4-hydroxy benzoate estars, phenol, xylenol derivatives and salicylic acid. The calibration graphs for methyl, ethyl, propyl and butyl-4-hydroxybenzoates were rectilinear for the range 0.5 to 4 mg. The method was used to determine 4-hydroxybenzoates in soya sauce. 

When Cl and MeO substituents are attached to the phenolic ring, the PFR may result in displacement of those substituents by the acyl moiety. An example of chlorine displacement has been given in Section I, whereas Scheme 10 shows the case of 2-methoxy-4-methylphenyl benzoate (26), where the reaction mixture contains 2-hydroxy-5-methylbenzophenone (27), a product of methoxy substim-tion [37]. Hageman also reported the substitution of MeO by acetyl in the photolysis of 4-methoxyphenyl acetate and related esters [32]. 

This method of quantum yields calculation was verified in more detail in studying the photorearrangement of 4-methylphenyl benzoate (60) (in ethanol with 253.7 nm).71 The quantum yield of ester decrease, Additional examples are calculations of the photorearrangements of poly-4-benzoyloxystyrene (in dioxane with 253.7 nm) (cpA = 0.082, methyl-phenyl acrylate ([Pg.138]

Zeolites H-BEA and H-Y were found to be the most active catalysts, however all catalysts readily form the phenyl benzoate (Table 4.1). In the conditions of the reaction, the formation of phenyl benzoate (PB) occurs rapidly via O-acylation of phenol. Direct C-alkylation of phenol with benzoic anhydride (B) and Fries rearrangement of phenyl benzoate results in the formation of 2- and 4-hydroxy-benzophenones (2-HPB and 4-HPB) (Scheme 4.3). 

Heating a phenol ester in the presence of Nafion-H gave good yields of the hydroxy phenyl ketone.This Fries rearrangement gave a mixture of the ortho and para hydroxy compounds in a 1 2-2.5 ratio (Eqn. 22.19). A study of the rearrangement of phenyl benzoate over a number of solid acid catalysts indicated that Nafion-H was more effective than montmorilIonite or amorphous aluminum silicate for this reaction. " ... 

CIC Vanillin, the main component in vanilla flavour is the basic key ingredient for the creamy, sweet character. All other volatile flavouring compounds have been identified only in small traces. Among them 2-methoxy phenol and 2-methoxy-4-vinyl phenol are responsible for the phenolic, smoky odour. 4-Methoxy benzalde-hyde, 3,4-methylene-dioxy-benzaldehyde, methyl benzoate and methyl ciimamate impart the warm, powdery, aromatic floral character. Vitispirane adds a fruity, floral topnote. Natural vanilla extract blends very well with other flavourings and it has been modified in different directions ethyl vanillin is used to increase the sweet, creamy vanillin aspect. Tonka beans and coumarin add a full, dried hay, slightly caramel-like custard aspect, supported by the butter notes of diacetyl and 4-hydroxy-decanolide. 

The use of ethyl [2-13C]acetoacetate instead of diethyl [2-t3CJmafonafe in the condensation reaction with 4H-pyran-4-one afforded ethyl 4-hydroxy[1 -13C]benzoate in 87% yield. In this case, 1.1 equiv of 4H-pyran-4-one and 1.1 equiv of potassium tert-butoxide were optimal. The addition of catalytic amounts of the base was not satisfactory. Ethyl [2-13C]acetoacetate was prepared from ethyl (2-13C]acetate as described for diethyl [2-13C]matonate.16 The maximum yield for this reaction on a 10-mmol scale was only 70% after distillation. 4H-Pyran-4-one reacted with nitromethane and potassium tert-butoxide (each 1.1 equiv) to afford 4-nitrophenol in 75% yield after purification by flash chromatography. This gives easy access to 4-nitro[4-13C]phenol. With 2,4-pentanedione, the condensation with 4H-pyran-4-one under the same reaction conditions gave 4-hydroxyacetophenone in 45-50% yield after purification. 

Unmodified BEA zeolite, on the other hand, shows the highest activity in the acylation of phenol wifh benzoic anhydride. Phenyl benzoate (PB) is the main product (61% yield), accompanied by C-acylated products (35%), with an interesting para-selectivity (ortho/para = 0.48). When the reaction time is increased from 4 to 20 h, an increase in para-hydroxy-benzophenone yield (from 11% to 23%) fogefher wifh a decrease in PB yield (from 79% to 64%) is observed however, a small increase in the orf/zo-hydroxybenzophenone yield (from 9% to 10%) cannof be avoided. The acfivify of the catalyst, together with its selectivity, does not distinctly decrease when the catalyst is used from fresh to firsf recycle. 

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