Citric acid, molecular model

O Create a large version of the citric acid cycle. You may want to create a large bulletin-board display or a hanging mobile, using three-dimensional molecular models. Whatever the format of your citric acid cycle, make sure that it is completely and accurately labelled. 

Many organic acids occur in the vegetable kingdom. The molecular models show ascorbic acid, also known as vitamin C (CgHgOg), and citric acid (CgHgOv) (from lemons, oranges, and tomatoes) and oxalic acid (H2C2O4) (from rhubarb and spinach). 

As far as the 1953 selection of the Nobel Prize winners for science is concerned, one could look at this event as a perfect stage management of the Nobel Committee. The Nobel Prize for Medicine and Physiology went to Hans Krebs for the Citric acid cycle and enzymatic reactions , to Fritz Lipmann for Coenzyme A , and the Nobel Prize for Chemistry to Hermann Staudinger [7, p. 1064]. In addition, Watson and Crick had just rang in molecular biology definitely with their Nature article on their DNA model [18]. 

In the chemical modeling approach, the simultaneous extraction of citric acid and water by alcohols is interpreted by the solvation and hydration processes in the alcoholic phase. In a simplest molecular model, it is assumed that only one predominant citric acid complex (solvate) is formed, and the partition process can be treated as the following chetnieal reaction... 

There is reasonable agreement between results coming from systematic poten-tiometric determinations performed by Bates and Pinching [6], De Robertis et al. [7], Benezeth et al. [8] and Yadiv et al. [10]. The reported values from electrical conductivity measurements which were performed by Apelblat and Barthel [9] are similar but systematically lower. However, in the analysis of conductometric measurements, the final results depend not only on chosen molecular model but also on applied conductivity equation. The analysis of old conductivities of citric acid which were determined by Jones [12] was performed by Apelblat et al. [13]. 

The molecular model below represents citric acid, an acidic component of citrus juices. Represent bonding in the citric acid molecule using the method of Figure 11-19 to indicate hybridization schemes and orbital overlaps. 

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