O-Acetals

The ester and catalj st are usually employed in equimoleciilar amounts. With R =CjHs (phenyl propionate), the products are o- and p-propiophenol with R = CH3 (phenyl acetate), o- and p-hydroxyacetophenone are formed. The nature of the product is influenced by the structure of the ester, by the temperature, the solvent and the amount of aluminium chloride used generally, low reaction temperatures favour the formation of p-hydroxy ketones. It is usually possible to separate the two hydroxy ketones by fractional distillation under diminished pressure through an efficient fractionating column or by steam distillation the ortho compounds, being chelated, are more volatile in steam It may be mentioned that Clemmensen reduction (compare Section IV,6) of the hj droxy ketones affords an excellent route to the substituted phenols. 

Furfural — see Furan-2-oarbaldehyde, 532 Furfuryl acetate, o -(butoxycarbonyl)-anodic oxidation, 1, 424 Furfuryi acrylate polymerization, 1, 279 Furfuryl alcohol configuration, 4, 544 2-Furfuryl alcohol polyoondensation, 1, 278 reactions, 4, 70-71 Furfuryl alcohol, dihydro-pyran-4-one synthesis from, 3, 815 Furfuryl alcohol, tetrahydro-polymers, 1, 276 rearrangement, 3, 773 Furfuryl chloride reactions... 

The toliowing remarks are applicable to the samples referred to in the table. Mos. I anti 2 eootained lerpiiiyl acetate o. 3 was a pare, but old reainified oil, aa the analjitis petformed on it after steam diatil-latiou proved No. 4 contained glyceryl acetate No.. fi was a pure oil. 

AA = acetanilide p-APT = N-(p-methylphenyl) acetamide m-AABA = m-acetamino benzoic acid m-AAl = m-acetamino phenylmetha-nol m-AAe = o-acetaminophenylmethyl acetate o-AABA = o-acetaminobenzoic acid o-AAl = o-acetaminophenylmethanol o-AAe = o-acetaminophenylmethyl acetate. 

The diastereoselectivity of the reaction may be rationalized by assuming a chelation model, which has been developed in the addition of Grignard reagents to enantiomerically pure a-keto acetals7,8. Cerium metal is fixed by chelation between the N-atom, the methoxy O-atom and one of the acetal O-atoms leading to a rigid structure in the transition state of the reaction (see below). Hence, nucleophilic attack from the Si-face of the C-N double bond is favored4. 

FIGURE 3. Hammett plots for bases and substituted phenols refers to ethyl acetate, O lV,JV-dimethylacetamide, DMSO, A pyridine and x triethylamine. 

Conversion of Carbonyl Croups, their 0,0- and 0,N-Acetals, O-Silylenoethers 111 5.2... 

Isopropenyl acetate O Vinyl acetate O Vinyl butanoate O Vinyl octanoate 97 68... 

Figure 1. Specific activity of cutinase as a function of sole carbon source in the growth medium. The T-8 strain of F. solani was grown on 0.5% acetate (o), 1.5% acetate (A), or 1.5% glucose ( ) as the sole carbon source. (Reproduced with permission from Ref. 13. 1986, American Society for Microbiology.)...

Highest yields are obtained when the reaction is carried out in boiling toluene until all water and ethanol are eliminated by azeotropic distillation. Other /S-ketocarboxylic esters such as ethyl benzoyl acetate, o-methoxybenzoyl acetate and ethyl acetonedicarboxylate react similarly with aromatic amidoximes (50). 

Figure 4. Variation in the polymer-polymer interaction parameter, B with hydroxy content of ethyl lignin (X), lignin acetate (O), unmodified lignin ( ), and hydroxypropyl lignin (—).

Figure 3.5 Catalytic efficiency of SBP-catalyzed oxidation of p-cresol in acetonitrile ( ) and ethyl acetate (O) as a function of ow. Enzymatic activity increases over 5 orders of magnitude as water is added to the system [60].

Fio. 3. Sedimentation coefficient and molecular weight as functions of pH. (A) Sedimentation coefficients as a function of pH. (O) s°0 w values were determined for samples adjusted from neutral pH to each pH value. The concentrations were 72 mg/ml, except at pH 5 and pH 4, where they were 4j0 mg/ml in 0.01 Af tris-0.01 Af sodium acetate. (0) s°0 w values were determined for samples adjusted from neutral pH to the given pH. Concentrations were 0.62 mg/ml in 0.1 Af NaCl-0.01 Af tris-0.01 M sodium acetate. ( ) s° w values were determined for samples prepared at pH 2, then dialyzed at the appropriate pH. Concentrations were 0.62 mg/ml in 0.1 M NaCl-0.01 Af tris-0.01 M sodium acetate. (O) Determinations with Schlieren optics all other determinations were made with the use of ultraviolet optics with the photoelectric scanner. (B) Weight average molecular weight as a function of pH. (0) M values were determined for samples adjusted from neutral pH to each pH indicated, by dialysis, 0.62 mg/ml, in 0.1 M NaCl-0.01 M tris-0.01 M sodium acetate. (O) Mw values were determined for samples prepared at pH 2, then dialyzed at the appropriate pH, 0.62 mg/ml in 0.1 M NaCl-0.01 Af tris-0.01 Af sodium acetate. 

Directly or after LLE with ethyl acetate o-dichloromethane, RP-HPLC C, 8 orC8, UV 254 nm... 

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