4 Tartaric Acid Is A Molecule With Three Stereoisomers D Tartaric Acid L Tartaric Acid And Meso Tartaric Aci 1 (30.59 KiB) Viewed 60 times
4 Tartaric Acid Is A Molecule With Three Stereoisomers D Tartaric Acid L Tartaric Acid And Meso Tartaric Aci 2 (37.74 KiB) Viewed 60 times
4. Tartaric acid is a molecule with three stereoisomers, D-(-)-tartaric acid, L-(+)-tartaric acid, and meso-tartaric acid. The synthetic form of tartaric acid (the product produced in a laboratory) has an optical rotation of 0°. The meso isomer is also optically inactive. But, the melting points of the synthetic tartaric acid and the meso-tartaric acid are very different. (a) Is it possible that the synthetic form of tartaric acid is the meso isomer? Why or why not? (b) Why is the meso isomer optically inactive? (c) If the synthetic form is not the optically inactive meso isomer, why might the synthetic form have an optical rotation of 0°?
3. Look up specific rotation literature values for (+)-a-pinene and (-)-B-pinene and put them in the table below. Sample (+)-a-pinene (-)-B-pinene Specific Rotation Literature Value How do these values compare to your data? Explain why the literature values might be different from your data. III. Questions 1. Based on your experimental data, predict the specific rotation of (-)-a-pinene. 2. a-D-Lactose has a specific rotation of +92.6° and B-D-lactose has a specific rotation of +34.0°. If either anomer is dissolved in water and allowed to stand until equilibrium is reached, the specific rotation of the equilibrium mixture is +52.3°. Calculate the percentage of each isomer in the equilibrium mixture. 3. a-Pinene and 3-pinene are terpenes. What is a terpene?
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