Guaiacol process

No residual guaiacol can be found in vanillin produced by the guaiacol process. In contrast to vanillin from lignin, vanillin from guaiacol is extremely consistent in quaUty owing to the consistency of the supply source, and shows no variation in taste, odor, or color. 

The guaiacol process yields vanillin with consistent high quality and sufficient volume to meet demand. At present, this process is advantageous relative to alternate routes from waste lignosulfonates obtained from the pulp and paper industry and an ort/io-chloronitrobenzene (OCNB) process that has environmental concerns [33]. 

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. 

The manufacture of vanillin shows the progress made in the chemistry and chemical engineering of the substance. Most commercial vanillin is synthesized from guaiacol the remainder is obtained by processing waste sulfite Hquors. Preparation by oxidation of isoeugenol is of historical interest only. 

This process has the advantage that, under the reaction conditions, the glyoxyl radical enters the aromatic guaiacol ring almost exclusively para to the phenoHc hydroxyl group. Tedious separation procedures are thus avoided. 

Chlorinated phenolic compounds. Chlorinated phenolic compounds include phenols, guaiacols, catechols, and vanillins substituted with from one to five chlorine atoms per molecule. Typically, bleaching processes that result in the formation of 2,3,7,8-TCDD and... 

Synthesis from Guaiacol. In a process developed in the former Soviet Union, guaiacol is esterified with propionic acid, and the resulting guaiacyl propionate... 

For the synthesis several processes have been described using different natural starting materials, such as coniferin, eugenol, guaiacol and lignin (for reviews, see [22, 44, 48, 60, 61]. 

When camphene reacts with guaiacol (2-methoxyphenol), a mixture of terpenyl phenols is formed. Hydrogenation of the mixture results in hydrogenolysis of the methoxy group and gives a complex mixture of terpenyl cydohexanols (eg, 3-(2-isocamphyl) cyclohexanol [70955-714] (45)), which after fractional distillation produces a useful sandalwood fragrance product (85). A similar process has also been developed using catechol and camphene (86). 

Different histochemical tests have been used for peroxidase identification. Benzidine (4.33) has been used as a staining reagent, as well as guaiacol (4.34) and pyrogallol (4.35). However, until the 1970s, no reliable methods were known that allowed a sharp discrimination between oxidase and peroxidase activities (Maehly and Chance, 1954). Harkin and Obst (1973) reported the syringaldazine (4.36) histochemical test for peroxidase. This test permitted the proof of exclusive peroxidase participation in the lignification process. 

Other plants such as potatoes, cauliflower, cherries, and soybeans and several fungi may also be used as sources of peroxidase enzymes. Soybeans, in particular, may represent a valuable source of peroxidase because the enzyme is found in the seed coat, which is a waste product from soybean-based industries [90]. In this case, it may be possible to use the solid waste from the soybean industry to treat the wastewaters of various chemical industries. In fact, the direct use of raw soybean hulls to accomplish the removal of phenol and 2-chlorophenol has been demonstrated [105]. However, it should be noted that this type of approach would result in an increase in the amount of solid residues that must be disposed following treatment. Peroxidases extracted from tomato and water hyacinth plants were also used to polymerize phenolic substrates [106], Actual plant roots were also used for in vivo experiments of pollutant removal. The peroxidases studied accomplished good removal of the test substrate guaiacol and the plant roots precipitated the phenolic pollutants at the roots surface. It was suggested that plant roots be used as natural immobilized enzyme systems to remove phenolic compounds from aquatic systems and soils. The direct use of plant material as an enzyme source represents a very interesting alternative to the use of purified enzymes due to its potentially lower cost. However, further studies are needed to confirm the feasibility of such a process. 

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