D isomer: Difference between revisions
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The D isomer is one of two forms of [[ | The D isomer is one of two forms of [[Optical isomerism|optical isomer]], arising from the prescence of a [[Chiral carbon|chiral carbon]], which can rotate plane polarized light either clockwise or anticlockwise. 'D' stands for dextrorotary, meaning that the isomer rotates plane polarised light clockwise.<ref>http://www.elmhurst.edu/~chm/vchembook/209optical.html</ref> | ||
In natural [[Sugar|sugars]], the D isomer occurs more commonly than the [[L isomer|L is]]<span style="line-height: 1.5em;">[[L isomer|omer]], although it is not clear why, and often the two isomers can have widely diffferent effects.</span><ref>https://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/sugar.htm</ref> | In natural [[Sugar|sugars]], the D isomer occurs more commonly than the [[L isomer|L is]]<span style="line-height: 1.5em;">[[L isomer|omer]], although it is not clear why, and often the two isomers can have widely diffferent effects.</span><ref>https://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/sugar.htm</ref> | ||
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In molecules where more than one [[Chiral centre]] is present, the assignment of D or L is given according to the arrangement of functional groups on the highest numbered chiral carbon. | In molecules where more than one [[Chiral centre]] is present, the assignment of D or L is given according to the arrangement of functional groups on the highest numbered chiral carbon. | ||
A well known example of the difference between D and L isomers is that of [[Thalidomide|Thalidomide]], which was in the past given to pregnant women to counter the effects of [[Morning sickness|morning sickness]]. The drug was given as a [[Racemic mixture|racemic mixture]], which contains equal amounts of L and D enantiomers, therefore counteracting the ability to rotate plane polarize light in either directon, and while the D isomer was effective at curing morning sickness, the L isomer caused severe limb abnormalities in the developing [[Foetus|foetus]]. Thousands of children were born with abnormal or underdeveloped limbs, and thalidomide was banned in many countries. Since the thalidomide disaster, all chiral molecules are rigorously tested before being | A well known example of the difference between D and L isomers is that of [[Thalidomide|Thalidomide]], which was in the past given to pregnant women to counter the effects of [[Morning sickness|morning sickness]]. The drug was given as a [[Racemic mixture|racemic mixture]], which contains equal amounts of L and D enantiomers, therefore counteracting the ability to rotate plane polarize light in either directon, and while the D isomer was effective at curing morning sickness, the L isomer caused severe limb abnormalities in the developing [[Foetus|foetus]]. Thousands of children were born with abnormal or underdeveloped limbs, and thalidomide was banned in many countries. Since the thalidomide disaster, all chiral molecules are rigorously tested before being marketed to the public, and racemic mixtures are very rarely sold.<ref>http://www3.fed.cuhk.edu.hk/chemistry/files/chiraldrug.pdf</ref> | ||
=== References === | === References === | ||
Revision as of 12:25, 27 November 2017
The D isomer is one of two forms of optical isomer, arising from the prescence of a chiral carbon, which can rotate plane polarized light either clockwise or anticlockwise. 'D' stands for dextrorotary, meaning that the isomer rotates plane polarised light clockwise.[1]
In natural sugars, the D isomer occurs more commonly than the L isomer, although it is not clear why, and often the two isomers can have widely diffferent effects.[2]
In molecules where more than one Chiral centre is present, the assignment of D or L is given according to the arrangement of functional groups on the highest numbered chiral carbon.
A well known example of the difference between D and L isomers is that of Thalidomide, which was in the past given to pregnant women to counter the effects of morning sickness. The drug was given as a racemic mixture, which contains equal amounts of L and D enantiomers, therefore counteracting the ability to rotate plane polarize light in either directon, and while the D isomer was effective at curing morning sickness, the L isomer caused severe limb abnormalities in the developing foetus. Thousands of children were born with abnormal or underdeveloped limbs, and thalidomide was banned in many countries. Since the thalidomide disaster, all chiral molecules are rigorously tested before being marketed to the public, and racemic mixtures are very rarely sold.[3]
References