Vanillin chemical structure

Vanillin has been known as a flavouring substance since about 1816, and by 1858 the pure chemical had been obtained from ethanolic extracts of vanilla beans. It was not until 1872 that Carles established its correct formulation and in 1874, Tiemann and Haarmann reported it as 3-methoxy-4-hydroxy-benzaldehyde (Fig. 3.60). Finally, Reimer synthesized vanillin from guaiacol and thus proved its chemical structure. For many years, the most important source of vanillin was eugenol, from which it was obtained by oxidation. Today, the major portion of commercial vanillin is obtained by processing waste sulfite liquors, the rest through fully synthetic processes starting from guaiacol [21 ]. 

The reaction kinetic of the vanillin assay depends on the chemical structure. For (+)-catechin the reaction was terminated after 7 minutes,... 

Among the worldwide total of 30000 known natural products, about 80% stems from plant resources. The number of known chemical structures of plant secondary metabolites is four times the number of known microbial secondary metabolites. Plant secondary metabolites are widely used as valuable medicines (such as paclitaxel, vinblastine, camptothecin, ginsenosides, and artemisinin), food additives, flavors, spices (such as rose oil, vanillin), pigments (such as Sin red and anthocyanins), cosmetics (such as aloe polysaccharides), and bio-pesticides (such as pyrethrins). Currently, a quarter of all prescribed pharmaceuticals compounds in industrialized countries are directly or indirectly derived from plants, or via semi-synthesis. Furthermore, 11% of the 252 drugs considered as basic and essential by the WHO are exclusively derived from plants. According to their biosynthetic pathways, secondary metabolites are usually classified into three large molecule families phenolics, terpenes, and steroids. Some known plant-derived pharmaceuticals are shown in Table 6.1. 

Pino-Garcia and Rasmuson [12] investigated the influence of additives of similar chemical structure on the crystallization of vanillin (Figure 6.5). With few exceptions, a reduction in interfadal energy was derived from nucleation data. In this paper, the authors also used molecular modeling in an attempt to rationalize the experimental observations, as will be discussed in more detail subsequently. 

During the first half of the nineteenth century, the importance of the single odorous chemicals contained in natural products was recognized, and efforts were devoted to their isolation and characterization. Soon after, their synthesis was carried out by chemical methods. Cinnamaldehyde was first isolated in 1834 and then synthesized in 1856 by Chiozza [2]. In 1874, Hemann and Haarmann deduced the chemical structure of vanillin, and found a synthesis from coniferin, a glucoside of isoeugenol found in pine bark [3]. In 1876, Reimer prepared vanillin from guaiacol [4, 5]. 

Figure 3 Accessing the WWW chemical structures database through the Web Interface. The input structure is vanillin, queried by a full-structure search. The hit list and one selected entry from the list are displayed in separate windows. Below the shown part of the selected entry, a Java molecule viewer displaying the structure in 3D and a clickable map of Web pages referring to the entry are hidden...

Essential oils are organic compounds derived from flowers, seeds, leaves, roots, resins, and citrus fruits. The structures of many fragrant compounds have been studied, and processes for making these valuable compounds in a laboratory have been developed. There are now approximately 5000 synthetically produced chemicals that are available to a perfumer. These chemicals include vanillin, rose oxides, and the damascenes, or rose ketones. 

Figure 4.1. The 2-D (left) and 3-D (right) structures of synthetic or naturally occurring vanillin, the chemical that gives vanilla extract its characteristic flavour and smell. Neither representation of the structure provides a guide to the fact that humans like its flavour or smell, or indeed that the human nose can specifically detect the molecule.

Many aldehydes are particularly fragrant. A number of flowers, for example, owe their pleasant odor to the presence of simple aldehydes. The smells of lemons, cinnamon, and almonds are due to the aldehydes citral, cinnamalde-hyde, and benzaldehyde, respectively. The structures of these three aldehydes are shown in Figure 12.21. The aldehyde vanillin, introduced at the beginning of this chapter, is the key flavoring molecule derived from the vanilla orchid. You may have noticed that vanilla seed pods and vanilla extract are fairly expensive. Imitation vanilla flavoring is less expensive because it is merely a solution of the compound vanillin, which is economically synthesized from the waste chemicals of the wood pulp industry. Imitation vanilla does not taste the same as natural vanilla extract, however, because in addition to vanillin many other flavorful molecules contribute to the complex taste of natural vanilla. Many books made in the days before acid-free paper smell of vanilla because of the vanillin formed and released as the paper ages, a process that is accelerated by the acids the paper contains. 

Structurally, the difference between the chemical cause of hangovers and the taste of vanilla ice cream is simply a methyl group versus a substituted phenyl group. But, what a difference this switch makes Lovers of vanilla ice cream would not be pleased if the vanillin in their dessert were replaced by acetaldehyde ... 

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