Anisole Methoxybenzene

Ciesol and xylenol can be prepared by the methylation of phenol with methanol over both acid and base catalysts. It is postulated that phenol methylation on acid catalysts proceeds through the initial formation of anisole (methoxybenzene [100-66-3]) followed by intramolecular rearrangement of... 

Say you have to separate a mixture of benzoic acid (1), phenol (2), p-tolui-dine (4-Methylanaline) (3), and anisole (methoxybenzene) (4) by extraction. The numbers refer to the class of compound, as previously listed. We re assuming that none of the compounds react with any of the others and that you know we re using all four types as indicated. Phenol and 4-methylanaline are corrosive toxic poisons and if you get near these compounds in lab, be very careful. When they are used as an example on these pages, however, you are quite safe. Here s a sequence of tactics. 

It might seem that the Vs,min and Vs,max on a suitable molecular surface should indicate sites susceptible to electrophilic and nucleophilic reactants, respectively. Such reasoning has had some success in the past [3,14,16,17], but it is not reliable. For example, shown in Figure 17.2 is the electrostatic potential on a surface of anisole (methoxybenzene), 1, which is well known to undergo electrophilic attack at the ortho and para positions. 

The initiator formed from VCLt and A1(C2H5)2C1 is one of the most efficient means for syndioselective polymerization of propene, especially in the presence of a Lewis base such as anisole (methoxybenzene) [Doi, 1979a,b Natta et al., 1962 Zambelli et al., 1978, 1980], Other vanadium compounds such as vanadium acetylacetonate and various vanadates [VO(OR)xClp x), where x — 1,2,3] can be used in place of VCI4 but are more limited in their stereoselectivity [Doi et al., 1979]. Trialkylaluminum can also be used as a coinitiator, but only for VCI4. Syndiotacticity increases with decreasing temperature most of these syndioselective polymerizations are carried out below —40°C and usually at —78°C. The initiators must be prepared and used at low temperatures since most of them undergo decomposition at ambient and higher temperatures. There is considerable reduction of V(III) to V(II) with precipitation of ill-defined products that are low in activity and do not produce syndiotactic polymer, when the initiators are prepared at or warmed to temperatures above ambient. 

The trisubstituted benzene 14 was used by Woodward as a starting material for his synthesis of the natural product reserpine.5 It too has to be made. We shall not add the MeO group but buy anisole (methoxybenzene) as starting material. Both nitrogens will be added by nitration but in which order ... 

Chemical Name anisole, methoxybenzene, methyl phenyl ether... 

When the sodium salt of a phenol is treated with an alkyl halide or an alkyl sulfate, 0-alkylation occurs and an ether is formed, usually in good yield. Methyl ethers such as anisole (methoxybenzene) can also be formed in excellent yield by treatment of a phenol with diazomethane (Scheme 4.8). 

N-CIDNP was used to investigate photoinduced nitrations of aromatic compoimds ArH with tetranitromethane. The polarizations invariably arise from radical pairs ArH NO, but the experiments reveal different pathways of formation of these pairs. With a substrate such as 1,2-dimethoxybenzene, the precursor multiplicity is triplet and the pairs are produced by a dissociative electron transfer from the aromatic compound to tetranitromethane, which then cleaves into an NO2 radical and C(N02)3. In contrast, the very similar substrate anisole (methoxybenzene) exhibits polarizations indicating a singlet precursor, and the radical pair is thought to be formed by decomposition of a preceding unstable diamagnetic intermediate, most probably a nitro-trinitromethyl adduct. ... 

Fig. 9.3. MO diagram for anisole (methoxybenzene) showing effects of medioxy substituent.

The zeolite-catalysed alkylation of phenol or anisole (methoxybenzene) with methanol is a complex sequence of reactions taking place within ZSM-5 and ZSM-11 at 200-300 °C. As shown in Figure 4.3 (overleaf), the primary products are anisole and cresols (ortho-, rneta- and /7ara-methylphenols), but lesser amounts of xylenols (dimethylphenols) and methylanisoles are also found. Alkylation of both the benzene ring and the oxygen atom is faster when zeolite Y is used, but the selectivity for ortho-crQsol is greater when ZSM-5 or ZSM-11 is the catalyst. 

At 60 MHz, this chemical shift difference results in a complicated second-order splitting pattern for anisole (methoxybenzene), but the protons do fall clearly into two groups, the ortholpara protons and the meta protons. The 60-MHz NMR spectrum of the aromatic portion of anisole (Fig. 5.40) has a complex multiplet for the o,p protons (integrating for three protons) that is upheld from the meta protons (integrating for two protons), with a clear distinction (gap) between the two types. Aniline (aminobenzene) provides a similar spectrum, also with a 3 2 split, owing to the electronreleasing effect of the amino group. 

One can thus use tt values (Table 2.16) to estimate for a compound when an experimental value is not available providing is known for a related compound that differs from the unknown by one or at the most two substituents. For example, if log for anisole (methoxybenzene) is known to be 2.11, one would predict that logiifow for 3-chloroanisole would be 2.11 - - 0.77 = 2.88. This procedure illustrates the concept of linear free energy relations (LFERs) that depends on the fact that the different components of an organic molecule interact both with one another and their environment in a consistent manner and the behavior of the molecule can be defined as the sum of its components. 

To brominate phenol, all we had to do was to mix bromine and phenol—if we do this with benzene itself, nothing happens. We therefore say that, relative to benzene, the OH group in phenol activates the ring towards electrophilic attack. The OH group is both activating and ortho, para-directing. Other groups that can donate electrons also activate and direct ortho, para. Anisole (methoxybenzene) is the enol ether equivalent of phenol. It reacts faster than benzene with electrophiles. 

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