Methyl guaiacol

Anodic treatment of 4-methyl guaiacol (51) by the elaborated protocol using HFIP at BDD anodes yields exclusively the ortho-meta coupled product 52. Based on the previous results a selective ortho coupling to symmetric products was anticipated. 

The observed chemoselectivity is unique. Anodic treatment on BDD of 3,4,5-trimethoxy toluene results in the exclusive formation of the mixed biaryl 56. This method can be further performed with benzo[l,3]dioxole-containing arenes as reaction partners, giving biaryls 57 and 58 in acceptable yields. Furthermore, naphthalene moieties can be directly located onto 4-methyl guaiacol as the products 59 and 60 reveal. This novel cross-coupling can be expanded to other phenolic reaction partners as well [28]. The displayed selection of mixed biaryls 53-60 is accessible in a single step. In the workup protocol, HFIP is almost quantitatively recovered since it represents the most volatile component in the electrolyte. In addition, nonconverted starting materials can be recycled by short path distillation with approximately 80% efficiency (Scheme 23). 

Technically, the chemist could avoid the complex glassware apparatus of this procedure for a more crude approach [104]. This report shows some dudes de-methylating an amphetamine with concentrated HCI in a pressure cooker. A similar approach with good yields was also employed in ref. 83 and should work as well or better on guaiacol. Hydroiodic acid or hydrobromic acid will work better than hydrochloric acid but, you know, whatever floats the chemist s boat. To do this the chemist can just plain reflux HI or HBr with the guaiacol for a few hours and process as before or she can use HI, HBr or HCI and place the reactants in a pipe bomb for a few hours. 

In contrast to vanillin from lignin, the principal impurity found in vanillin from guaiacol is 5-methyl vanillin, typically present at levels of about 100 ppm in Rhovanil Extra Pure (Rhc ne-Poulenc), although levels as high as 3000 ppm have been found in samples from other producers. This impurity is completely odorless. 

Yields of 54% of 2-methoxy-4 -methyl diphenyl ether from -bromotoluene and guaiacol, and 60% of 2-mcthoxy-5-methyl-diphenyl ether from 3-bromo-4-methoxytoluene and phenol, have been obtained by the same method in the laboratory of the submitters,... 

The selectivity 3,0 is strongly dependent on the Mg content (Fig. 4). It increases with Mg concentrations up to 7 5%, passing through a maximum of S3.0 = 0.65. 3-methyl catechol becomes the main product at low conversion. It is worthwhile to note that only the relative formation of guaiacol and 3-methyl catechol are affected by the percentage of Mg added to alumina, 0-alkylation is reduced in favour of C-alkylation, but the ring methylation stays preferentially ortho-selective. 

The method allowed the authors to characterise a pine pitch (viscous tar derived from the distillation of wood of pine trees). The main constituents detected by headspace SPME result from the pyrolysis of the lignin, guaiacol (11) and its p-w-alkyl derivatives [methyl... 

A spectrophotometric determination of parathion-methyl (258) in soil and various vegetables is based on reduction of the nitro group to an amino group with zinc/HCl, dia-zotization and coupling with guaiacol (259) to form a yellow-colored azo dye in alkaline medium532. 

Figure 3.42. Scope of Rh/(if)-binap-catalyzed asymmetric 1,4-addition of potassium organotrifluoroborates to methyl iV-acetamidoacrylate in the presence of guaiacol.

It is noteworthy that the guaiacol which condenses is saturated with methyl bromide at the condensation temperature, so that it is necessary to prevent it from becoming warmer during its passage through the separator otherwise the evolution of gas may hinder the ready formation of layers. 

The water collected during the reaction contains practically no hydrobromic acid but is saturated with guaiacol and methyl bromide. Nevertheless, it scarcely pays to recover the dissolved compounds, for on distillation only 1-2 g. of wet guaiacol can be collected while the value of the methyl bromide is in any case not very great. 

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