Anisole acetate

In the Mukaiyama aldol additions of trimethyl-(l-phenyl-propenyloxy)-silane to give benzaldehyde and cinnamaldehyde catalyzed by 7 mol% supported scandium catalyst, a 1 1 mixture of diastereomers was obtained. Again, the dendritic catalyst could be recycled easily without any loss in performance. The scandium cross-linked dendritic material appeared to be an efficient catalyst for the Diels-Alder reaction between methyl vinyl ketone and cyclopentadiene. The Diels-Alder adduct was formed in dichloromethane at 0°C in 79% yield with an endo/exo ratio of 85 15. The material was also used as a Friedel-Crafts acylation catalyst (contain-ing7mol% scandium) for the formation of / -methoxyacetophenone (in a 73% yield) from anisole, acetic acid anhydride, and lithium perchlorate at 50°C in nitromethane. 

Figure 2.5 Relative occupancy (%) of the intracrystalline volume of a H-BEA zeolite during the transformation of a 2 1 molar anisole - acetic anhydride mixture in a batch reactor, assuming no adsorption of acetic acid and full occupancy of the micropores. Anisole ( ), acetic anhydride (o) and 4-methoxyacetophenone (x). Reprinted from Journal of Catalysis, Vol. 187, Derouane et al., Zeolite catalysts as solid solvents in Fine Chemicals synthesis 1. Catalyst deactivation in the Friedel-Crafts acetylation of anisole, pp. 209-218, copyright (1999), with permission from Elsevier...

Anisole acetylation, which was one of the main reactions investigated, was first shown to be catalysed by zeolite ten years ago by Bayer (13), which was confirmed by Harvey et al. (14), then by Rhodia (15). Large pore zeolites and especially those with a tridimensional pore structure such as HBEA and HFAU were found to be the most active at 80°C, in a batch reactor with an anisole/acetic anhydride molar ratio of 5 and after 6 hours reaction, the yield in methoxyacetophenone (MAP) was close to 70% with HBEA and HFAU zeolites, to 30% with HMOR and 12% with HMFI. With all the zeolites and also with clays and heteropolyacids, the selectivity to the para-isomer was greater than 98%, which indicates that this high selectivity is not due to shape selective effects but rather to the reaction mechanism (electrophilic substitution). The lower conversion observed with HMOR can be related to the monodimensional pore system of this zeolite which is very sensitive to blockage by heavy secondary products. Furthermore, limitations in the desorption of methoxyacetophenone from the narrow pores of HMFI are probably responsible for the low activity of this intermediate pore size zeolite. 

The anisole/acetic anhydride ratio has a large effect both on the initial apparent reaction rate and on deactivation. Thus, in a fixed bed reactor with an anisole rich feeding mixture (anisole/acetic anhydride of 5) the maximum conversion of anisole is obtained at short contact time whereas a plateau at only half of the maximum conversion is found at long contact time with an equimolar mixture (Figure 14.2). Moreover, deactivation is much faster in this latter case (16). 

Electrophilic Anisole Acetic anhydride ((C4F,S03)2N)3Yt 4-Methoxy- acetophenone 97... 

Bromine (310 g., 1.94 moles) is introduced into a cooled solution of 200 g. (1.85 moles) of anisole in 750 g. of glacial acetic acid by passing a stream of air through the bromine and then into the reaction flask containing the anisole-acetic acid solution. (Hood.) After introduction of the bromine, the acetic acid solution is a light-yellow... 

Among them the HY and Hb exhibit the best activity as previously reported (refs. 3c, 3d). Optimisation of the reaction parameters underlines the following trends In general, an increase of the molar ratio anisole/acetic anhydride, the amount of catalyst as well as the temperature, is benefitial for the activity. 

The kinetics of nitration of anisole in solutions of nitric acid in acetic acid were complicated, for both autocatalysis and autoretardation could be observed under suitable conditions. However, it was concluded from these results that two mechanisms of nitration were operating, namely the general mechanism involving the nitronium ion and the reaction catalysed by nitrous acid. It was not possible to isolate these mechanisms completely, although by varying the conditions either could be made dominant. 

It was shown that in preparative experiments sulphuric acid markedly catalysed, and acetate ions markedly anticatalysed the nitration of anisole. ... 

The authors of this work were concerned chiefly with additions to alkenes, and evidence about the mechanism of aromatic nitration arises by analogy. Certain aspects of their work have been repeated to investigate whether the nitration of aromatic compounds shows the same phenomena ( 5-3-6). It was shown that solutions of acetyl nitrate in acetic anhydride were more powerful nitrating media for anisole and biphenyl than the corresponding solutions of nitric acid in which acetyl nitrate had not been formed furthermore, it appeared that the formation of acetyl nitrate was faster when 95-98% nitric acid was used than when 70 % nitric acid was used. 

Zeroth-order nitrations. The rates of nitration at 25 °C in solutions of acetyl nitrate (6xio —0-22 mol 1 ) in acetic anhydride of 0- and jw-xylene, and anisole and mesitylene were independent of the concentration and nature of the aromatic compound provided that... 

Acetoxylation and nitration. It has already been mentioned that 0- and m-xylene are acetoxylated as well as nitrated by solutions of acetyl nitrate in acetic anhydride. This occurs with some other homologues of benzene, and with methyl phenethyl ether,ii but not with anisole, mesitylene or naphthalene. Results are given in table 5.4. 

Other substituents which belong with this group have already been discussed. These include phenol, anisole and compounds related to it ( 5.3.4 the only kinetic data for anisole are for nitration at the encounter rate in sulphuric acid, and with acetyl nitrate in acetic anhydride see 2.5 and 5.3.3, respectively), and acetanilide ( 5.3.4). The cations PhSMe2+, PhSeMe2+, and PhaO+ have also been discussed ( 9.1.2). Amino groups are prevented from showing their character ( — 7 +717) in nitration because conditions enforce reaction through the protonated forms ( 9.1.2). 

Picolyl ethers are prepared from their chlorides by a Williamson ether synthesis (68-83% yield). Some selectivity for primary versus secondary alcohols can be achieved (ratios = 4.3-4.6 1). They are cleaved electrolytically ( — 1.4 V, 0.5 M HBF4, MeOH, 70% yield). Since picolyl chlorides are unstable as the free base, they must be generated from the hydrochloride prior to use. These derivatives are relatively stable to acid (CF3CO2H, HF/anisole). Cleavage can also be effected by hydrogenolysis in acetic acid. ... 

The first synthesis of p-methoxyphenyllead triacetate by direct plumbation was reported by Harvey and Morman, who obtained the compound in 2418 yield by heating anisole and lead tetraacetate in acetic acid at SO C for 4... 

From the concentration of the solute in the solvent, and the total amount added the quantity of solute adsorbed on the stationary phase was also calculated. The results obtained for the solutes anisole and nitrobenzene are shown as graphs in Figure 12. One pair of curves refers to the polar solvent and relates the concentration of ethyl acetate in the solvent (Em) and the concentration of ethyl acetate in the stationary phase (Es) to the total mass of solute added. The other pair of curves refers to the... 

It should be first noted that the curves relating the concentration of ethyl acetate in the solvent mixture and on the stationary phase are straight and horizontal. As the initial concentration of ethyl acetate in mobile phase was 0.35 %w/v, the volume of mobile phase was 100 ml and the mass of silica was 10 g. It follows that, although a total of about 1.2 g of solute was added to the system, about a third of which resided on the silica surface, neither anisole nor nitrobenzene displaced any ethyl acetate from the silica gel. 

Katz et al. also plotted the distribution coefficient of n-pentanol, benzonitrile and vinyl acetate against the concentration of unassociated methanol in the solvent mixture and the results are shown in Figure 32. It is seen that the distribution coefficient of all three solutes is predominantly controlled by the amount of unassociated methanol in the aqueous solvent mixture. In addition, the distribution coefficient increases linearly with the concentration of unassociated methanol for all three solutes over the entire concentration range. The same type of curves for anisole and benzene, shown in Figure 33, however, differ considerably. Although the relationship between distribution coefficient and unassociated methanol concentration is approximately linear up to about 50%v/v of unassociated methanol, over the entire range the... 

The results from the overload of the more polar solute are similar to that for the aromatic hydrocarbons, but the effect of the overloaded peak on the other two appears to be somewhat less. It is seen that there is little change in the retention of anisole and acetophenone, although the band width of acetophenone shows a slight increase. The band width of benzyl acetate shows the expected band broadening... 

Acetylindole (213) was obtained by the action of ethyl acetate on indole magnesium iodide at low temperatures slightly higher yields were obtained when the reaction was carried out in anisole rather than in ether. Putochin subsequently observed that when the reaction was carried out in benzene at 85° both 213 and 3-acetylindole (109)... 

Phenyl-2-methyl CeHsMgBr 1. Anisole, 140 -150 2. Ammonium acetate 34 29... 

Then, 1-(3-acetylthio-2-methylpropanoyl)-L-proline is produced. The 1-(3-acetylthio-3-methyl-propanoyl)-L-proline tert-butyl ester (7.8 g) is dissolved in a mixture of anisole (55 ml) and trifluoroacetic acid (110 ml). After one hour storage at room temperature the solvent Is removed in vacuo and the residue is precipitated several times from ether-hexane. The residue (6.8 g) is dissolved in acetonitrile (40 ml) and dicyclohexylamine (4.5 ml) is added. The crystalline salt is boiled with fresh acetonitrile (100 ml), chilled to room temperature and filtered, yield 3 g, MP 187°C to 188°C. This material is recrystallized from isopropanol [ttlo -67° (C 1.4, EtOH). The crystalline dicyclohexylamine salt is suspended in a mixture of 5% aqueous potassium bisulfate and ethyl acetate. The organic phase is washed with water and concentrated to dryness. The residue is crystallized from ethyl acetate-hexane to yield the 1-(3-acetylthio-2-D-methylpropanoyl-L-proline, MP83°Cto 85°C. 

Benzhydryl 3-carbamoyloxymethyl-7j3-(2-thienylacetamido)-70 -methoxydecephalosporanate (300 mg) in 0.5 ml in anisole and 2.5 ml of trifluoroacetic acid is reacted for 15 minutes at 10°C. The resulting mixture is evaporated at reduced pressure and flushed twice with anisole. The residue is dissolved in methylene chloride and extracted with 5% sodium bicarbonate solution. The aqueous solution is adjusted to pH 1. B with 5% phosphoric acid and extracted with ethyl acetate. The organic solution is dried and evaporated to yield the pure 3-carba-moyloxymethyl-70 -methoxy-7/3-(2-thienylacetamido)decephalosporanic acid, MP 165°C to 167°C. This may then be converted to the sodium salt. 

C Nuclear magnetic resonance spectrum, acetaldehyde, 732 acetophenone, 732 anisole, 672 benzaldehyde, 732 benzoic acid, 771 p-bromoacetophenone, 449 2-butanone, 449, 732 crotonic acid. 771 cyclohexanol, 634 cyclohexanone, 732 ethyl benzoate, 477 methyl acetate, 443 methyl propanoate, 450 methyl propyl ether, 672... 

Only one example, showing high stereoselectivity, is known in this class of reactions. On treatment of the acyclic glycine cation equivalent 1 (see Appendix), containing the ( + )-cam-phor-10-sulfonamide ester as a chiral auxiliary, with boron trifluoridc and anisole at 0"C a mixture of aromatic substitution products is obtained in essentially quantitative yield 55. Besides 11 % of cuV/io-substitution product, the mixture contains (R,S)-2 and its (/ ,/ )-epimer in a ratio >96 4 (NMR). The same stereoisomer 2 predominates when the reaction is conducted in sulfuric acid/acetic acid 1 9, although the selectivity is slightly lower (91 9 besides 25% of ortho substitution). 

Rather different experimental results were obtained by de la Mare et a/.208, 209, who studied chlorination by hypochlorous acid in 51, 75 and 98 % aqueous acetic acid. With the latter medium, the chlorination of anisole or m-xylene (at an unspecified temperature) was independent of the concentration of aromatic, and catalysed by perchloric acid to a much greater extent than an equimolar amount of lithium perchlorate the reaction was also catalysed by the base, sodium acetate. The reactive species was postulated as chlorine acetate produced... 

De la Mare et al.260 measured the rates of chlorination of biphenyl, a wide range of its methyl derivatives, and anisole in acetic acid at 25 °C. Second-order rate coefficients (104 2) were biphenyl (6.40), 2-methylbiphenyl (3.20), 3-methyl-biphenyl (820), 4-methylbiphenyl (30.0), 2.2 -dimethylbiphenyl (4.40), 3.3 -dimethylbiphenyl (2,630), 4,4 -dimethylbiphenyl (70.0), 2,6 -dimethylbiphenyl (1,130), 3,4,3, 4 -tetramethylbiphenyl (19,300), anisole (12.5 x 104), and these results showed very clearly the effect of steric inhibition of resonance between the phenyl rings through the presence of ortho methyl groups260. Similar (but rather more emphatic) results were obtained262 in chlorination of the /-butyl derivatives for which the corresponding rate coefficients were 2-/-butylbiphenyl (1.0) 4-/-butylbiphenyl (25.7), 2,2 -di-/-butylbiphenyl (1.8), 4,4 -di-/-butylbiphenyl (70.0). 

The most extensive study of the effect of conditions upon the kinetics of bromination was made by Robertson et al.23l 279, who measured the rates of bromination of alkylbenzenes, acetanilide, aceto-p-toluidide, mesitylene, anisole and p-tolyl methyl ether in acetic acid at 24 °C. They found that at relatively high concentrations of bromine (A//40-M/100) the reaction is second-order in bromine, i.e. the rate equation is... 

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