A problem in optical isomerism . xamination of the following compound the starred carbon atom willhe seen to be pseudo-asymmetric, depending upon the configurationsof carbons (2) and (5). H QH55 C-—COOH \ /<% H Oct) GD^r^ H lt» ^1 CHSCK2—CH2 2,5 dirnethyl-cyclopentane — 1, carboxylic acid. Relative AsymmetryCyclic compounds may exhibit a special case 01 pseudo-asymmetry iaiown as relative asymmetry.^ for instance, if in thefollowing compound an observer be stationed at carbon-atom (1)and should swim on his side facing to the outside of the ringtoward carbon-atom (2) he would find on arrivin
A problem in optical isomerism . xamination of the following compound the starred carbon atom willhe seen to be pseudo-asymmetric, depending upon the configurationsof carbons (2) and (5). H QH55 C-—COOH \ /<% H Oct) GD^r^ H lt» ^1 CHSCK2—CH2 2,5 dirnethyl-cyclopentane — 1, carboxylic acid. Relative AsymmetryCyclic compounds may exhibit a special case 01 pseudo-asymmetry iaiown as relative asymmetry.^ for instance, if in thefollowing compound an observer be stationed at carbon-atom (1)and should swim on his side facing to the outside of the ringtoward carbon-atom (2) he would find on arriving there that the O^OHco c COOH / \\ COOH \/ h\\ , CW C C Csi H H carboxyl would be above him on his right hand and the hydrogen be-low him on his left. But, should he proceed thus toward carbon-atom (3) he would find reverse conditions - the carboxyl to hisleft and the hydrogen to his right. All three of the carbon-atoms in the compound shown above are therefore relatively asym- 1WisOicenus,B. ,34,,A.,245, 4- metric to each other and this asymmetry is destroyed if only one ofthe carboxyls he replaced by hydrogen. Cis-trans Asymmetry Geometrical isomerism is not to he confused with ordinarycarbon-atom asymmetry. The former deals with the question ofwhether substituting groups are on the same or opposite sides, ofthe plane of the ring in cyclic compounds, or of the double bondof unsaturated compounds. Geo metrical isomerism may be accompaniedby, but does not compulsorily include optical activity. Apparently jjon-symrnetrical Inactive These molecules are peculiar in that they may be dividedinto two halves, one of which is made the mirror-image of theother by rotating it thro gh an angle of ISO0, such a molecule isinactive. This is a case of indirect As is seen inthe diagram below, the lower half of (a) on rotation through 180°produces (b), which possesses a plane 01 Y X planeof B. _indirect__symmetry A ,1 Xy B (a) fh) Fig.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttheses, bookyear1917
