Vanillin from lignin

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. 

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. 

Preparation from Waste Sulfite Liquors. The starting material for vanillin production can also be the lignin present in sulfite wastes from the cellulose industry. The concentrated mother liquors are treated with alkali at elevated temperature and pressure in the presence of oxidants. The vanillin formed is separated from the by-products, particularly ace-tovanillone. 4-hydroxy-3-methoxyacetophenone, by extraction, distillation, and crystallization. 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, although levels as high as 3000 ppm have been found. This impurity is completely odorless. 

Pearl IA (1942) Vanillin from lignin materials J Am Chem Soc 64 1429-1431... 

Only Borregaard in Sarpsborg, Norway, still prepares vanillin from lignin. Under licence from Monsanto, Borregaard uses a process which differs from the previously used procedures by ultrafiltration of the sulfite washings. Thereby, low-molecular-weight components, which cannot be oxidised to vanillin, can be separated out. 

Vanilla flavoring in bakery goods, confectionery, and many fro2en desserts need not be natural vanilla. The artificial and synthetic vanilla flavors that are used include vanillin [121-33-5] from lignin (wood pulp), ethyl vanillin [121 -32-4] and vanitrope [94-86-0], the latter two are synthetics. Over 90% of the U.S. market for vanilla flavor contains vanillin. These synthetics continue to dominate the market because of availabiUty, quahty, and relatively low and stable prices. 

The process starting from lignin has faced serious problems, such as reduced availabiUty and environmental impact. The availabiUty is reduced because the new process for making paper paste yields less Hquor. As a result, it is likely that the larger companies will not reinvest in new factories to process Hquors to meet demand. The process s environmental impact is also problematic because over 160 t of caustic waste are produced for every ton of vanillin manufactured. 

Treatment of suberin with nitrobenzene generates vanillin, p-hydroxy benz-aldehyde, but not much syringaldehyde that arises mostly from lignin. 

The Norwegian company Borregaard makes vanillin by chemo-oxidation of cheap natural lignin. In view of the complexity of the lignin structure this is a remarkable achievement. This semi-synthetic vanillin is, however, not allowed to carry the qualification of natural . Borregaard is the only global producer of lignin-vanillin or wood-sourced vanillin , with a volume of about 2000 t a-1. They obtain 4 kg vanillin from one ton of wood. This vanillin is more expensive than synthetic vanillin, but the flavorist needs lower doses of the extra round flavor . 

Guaiacylglycerol-/3-coniferyl ether is a dimeric decomposition product of coniferous lignin dehydrodivanillin may be also formed by dimerization of vanillin after formation from lignin. Among the lignin decomposition products are mono-, di- and triphenol derivatives which are derived from the different types of lignin of needle trees, deciduous trees, or graminees. 

Vanillin, syringaldehyde, and related phenolic products derived from lignin appear to be important in the desirable odor contributed to beverages by oak barrels (25, 26, 27). These substances are present in the wood, but more appears in the beverage than simple extraction seems to allow. Also the odor of vanillin seems to increase with time and mellowing of the beverage compared with a fresh extract of new wood (25). 

For example, vanillin can be obtained via at least five different ways (i) by isolation from the orchid (Vanilla planifolia), which is a very expensive method (ii) by tissue culture followed by extraction (iii) by microbial transformation of eugenol, the main compound of clove (iv) from lignine by synthesis, and (v) from guaiacol, a natural aroma compound, with comparable molecular structure. Only the vanillin obtained via the first three methods is natural. The other routes afford a nature-identical vanillin. 

The homolytic evidence is further strengthened by the product distribution obtained from lignin. Both copper(II) and nitrobenzene give substantial and similar yields of aldehyde products (19). Benzoic acids rather than benzaldehy-des, however, are the expected terminal oxidation products from the action of heterolytic oxidants. If vanillin is produced from lignin via heterolytic oxidation by nitrobenzene, then the high survivability of an aldehyde in the presence of an... 

Vanillin occurs naturally in many essential oils and particularly in the pods of Vanilla planifolia and Vanilla tahitensis. Industrially, vanillin is prepared from lignin, which is obtained from the sulfite wastes produced during paper manufacture. Lignin is treated with alkali at elevated temperature and pressure, in the presence of a catalyst, to form a complex mixture of products from which vanillin is isolated. Vanillin is then purified by successive recrystallizations. 

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