Optical rotation Subject

In 1899 Thoms isolated an alcohol from Peru balsam oil, which he termed peruviol. This body was stated to have powerful antiseptic properties, but has not been further investigated until Schimmel Co. took up the subject. The oil after saponification was fractionated, and after benzyl alcohol had distilled over, a light oil with characteristic balsamic odour passed over. It boiled at 125° to 127° at 4 mm., and had a specific gravity 0 8987, optical rotation -1- 12° 22, and refractive index 1-48982. This body appeared to be identical with Hesse s nerolidol, whilst in physical and chemical properties it closely resembles peruviol. The characters of the various preparations were as follows —... 

A contemporaneous study on the same subject utilized a chemical correlation method where (—)-A-benzylargemonine chloride, obtained by sequential optical resolution and quatemization of ( )-7V-methylpavine (5), underwent a multistep degradative process to furnish (-)-A,A-dimethyl-di-H-propyl aspartate. Comparison of this final product with L-aspartic acid of known chirality led to the absolute configuration of (—)-5 (115,158). (—)-Eschscholtzine (9) was assigned the same absolute configuration by correlation of its ORD curve and optical rotation with those of (—)-argemonine (775). 

The achiral inorganic ionic sodium chlorate (NaClOs) and sodium bro-mate (NaBrOs) crystallize in enantiomeric forms belonging to the P2i3 space group for which the same crystal structures exhibit opposite optical rotation [89]. The levo-(Z) and dextrorotatory (d) crystals can be obtained in equal proportions [90]. The chiral ionic crystals of NaClOs and NaBrC>3 were subjected to asymmetric autocatalysis as the initial seed of chirality to study the correlation between the organic compound with high ee and the chiral inorganic crystal composed of achiral ionic components. 

The last subject in the discussion of inherently chiral compounds deals with the analysis of the aminoacids, peptides, and proteins. Most all of the remarks that were made about the steroids and carbohydrates regarding CD detection apply equally well to these. The enantiomeric purity of aminoacids is usually determined by their optical rotations at the sodium-D line. Rotations are normally so small that concentrated solutions and long pathlengths are needed. The detection is enhanced a little if laser illumination is used [66] or if ORD detection is done around 230 nm [71]. Without derivatization, only aminoacids with aromatic substituents are CD active in the near UV. Signals are generally weak and enantiomeric purity measurements are not quantitative. 

The large cardamom pericarp (husk) yielded 0.18% volatile oil by the Clevenger hydrodistillation method. This oil was analysed for physical parameters, e.g. specific gravity (0.9148), refractive index (1.4733) and optical rotation (-7.700). The volatile oil was subjected to GC-MS analysis and 37 compounds were identified, constituting > 98% of the total oil. The major compounds characterized were 1,8-cineole (38.7%), [3-pinene (13.6%), a-terpineol (12.6%), spathulenol (8.3%), 4-terpineol (4.5%), ger-macrene D (3.0%), a-pinene (2.8%) and (3-selinene (2.7%). GC and GC-MS data revealed that 1,8-cineole content was less than 50% when compared with the seed oil. Table 4.5 shows the major constituents separated by GC-MS (Rout et al., 2003). Figure 4.1 gives the structures of the major chemical components in the volatile oil from seeds. 

Addition of an excess of manganese dioxide to an aqueous solution of D-fructose, followed by shaking for 15 hours, changes the optical rotation from —92.5 to —16.9° through the formation of D-ara6ino-hexosulose. This was proved by the formation of a quinoxaline derivative on reaction with o-phenylenediamine. A comprehensive study on this subject has been published in this Series. ... 

Finally, an attempt was made by using Buck and Kobrich s method (ref. 77), which yields phenols by the reaction of lithiated aryl compounds with nitrobenzene. Compound (81) was treated with n-butyllithium at -10010 in THF in the presence of tetramethylethylenediamine followed by the addition of nitrobenzene. The crude products, which were difficult to isolate as phenolic compounds, were immediately methylated with diazomethane in ether solution. The products were subjected to preparative thin layer chromatography, affording two substances. One, obtained from the upper layer, was recrystallized from ethanol as colorless needles. It showed mp 162.5 163.5lC and an optical rotation of [ o ]D -110° (c= 0.14 in CHClj). The other one, isolated from the lower layer, was recrystallized from ethanol as colorless needles. It showed mp 185 — 187"C and an optical rotation of... 

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