Chloroform point group

The chloroform molecule will be used as an example for vibrational analysis. The CHCI3 molecule has one threefold axis of symmetry and three planes of symmetry. Chloroform thus belongs to the point group as discussed in Chapter 3. The symmetry elements, symmetry operations, selection rules, and vibration types have been discussed in detail in Section 3.6 where it was shown that chloroform has nine fundamental vibrations, three Ai vibrations, and three double degenerate type E vibrations. The results of the calculation to follow are presented in Fig. 14.6 where the forms of the vibrations are illustrated. 

This product was dissolved in 10 ml of chloroform. To this solution were added 10 ml of a 10% aqueous solution of caustic soda and the mixture was warmed at 50°C to effect hydrolysis of the ester group. After completion of the reaction, the organic phase was separated, washed with water and distilled to remove the solvent whereby 2.1 g (yield 4B%) of the end product, i.e., N-(3, 4 -dimethoxycinnamoyl)-anthranilic acid, were obtained. This product had a melting point of 211°C to 213°C. 

FIGURE 3.17 Reagents for protection of amino groups as the ferf-butoxycarbonyl derivatives. terf-Butyl chloroformate is rarely used because of its low boiling point. The oxime is 2-ferf-butoxycarbonyloximino-2-phenylacetonitrile,45 Boc20 = di-ferf-butyl dicarbonate, or di-terf-butyl pyrocarbonate.46 (Tarbell et al., 1972 Pozdvev, 1974). Acylations are carried out at pH 9 to avoid dimerization. 

At this point a benzaldehyde dimethylaeetal is used for the acetah-/ation. The thermodynamically favored six-membered acetal 15 is formed preferentially over the potential competitors five- and sev-cn-membereil acetals5 (See Chapter 7). Transformation of a primary alcohol function into the triflate group of structure 16 must precede the Sn2 reaction in the third step, in which a carbon nucleophile is created with LDA and chloroform. Dcprolonalion of chloroform with LDA is carried out at -110 C to suppress competing formation of dichlorocarbene.6... 

---