Posted by juan777 on Sunday, September 18, 2011 at 10:38pm.
In chemistry, an enantiomer ( /ɨˈnæntɪ.ɵmər/ ə-nan-tee-ə-mər; from the Greek ἐνάντιος, opposite, and μέρος, part or portion) is one of two stereoisomers that are mirror images of each other that are "non-superposable" (not identical), much as one's left and right hands are "the same" but opposite [1] (It can be clearly understood if you try to place your hands one over the other without touching the back or palm of the left to the same of the right. You observe that the thumb of one is always over the little-finger of the other, thus explaining the non-superimposable or non-coincident property known as chirality.)
Organic compounds that contain an asymmetric (chiral) Carbon usually have two non-superimposable structures. These two structures are mirror images of each other and are, thus, commonly called enantiomorphs (enantio = opposite ; morph = form) Hence, optical isomerism (which occurs due to this same mirror-image properties) is now commonly referred to as enantiomerism
Enantiopure compounds refer to samples having, within the limits of detection, molecules of only one chirality.[2]
Enantiomers have, when present in a symmetric environment, identical chemical and physical properties except for their ability to rotate plane-polarized light (+/−) by equal amounts but in opposite directions (although the polarized light can be considered an asymmetric medium). A mixture of equal parts of an optically active isomer and its enantiomer is termed racemic and has zero (± 0) net rotation of plane-polarized light.
Enantiomers of each other often show different chemical reactions with other substances that are also enantiomers. Since many molecules in the body of living beings are enantiomers themselves, there is often a marked difference in the effects of two enantiomers on living beings. In drugs, for example, often only one of a drug's enantiomers is responsible for the desired physiologic effects, while the other enantiomer is less active, inactive, or sometimes even responsible for adverse effects (unwanted side-effects).
Owing to this discovery, drugs composed of only one enantiomer ("entantiopure") can be developed to enhance the pharmacological efficacy and sometimes do away with some side effects. An example of this kind of drug is eszopiclone (Lunesta), which is enantiopure and therefore is given in doses that are exactly 1/2 of the older, racemic mixture called zopiclone. In the case of eszopiclone, the S enantiomer is responsible for all the desired effects, though the other enantiomer seems to be inactive; while an individual must take 2 mg of zopiclone to get the same therapeutic benefit as they would receive from 1 mg of eszopiclone, that appears to be the only difference between the two drugs
Wikipedia
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The formula for 2-pentanol is C5H12O.
However, when you draw the structure, be sure to make sure that the hydroxide branch is on one of the second carbons, because it is 2-pentanol. For example:
H
|
H O H H H
| | | | |
H - C- C - C- C - C - H
| | | | |
H H H H H
The structure could also very likewise be drawn with the hydroxide group going downwards or on the "4th" carbon (this term is incorrect, because the carbon is second from the right and therefore would be called the second carbon oncemore, but for clarity, I termed it the "4th" carbon).
Read more: //wiki.answers
NOw figure out where you can get the properties
As pentanol has one chiral centre, this style of presentation is best in a text format like this
CH3-C(H)-OH
(where the remainder of the chain is behind the page)
the other isomer is then
HO-C(H)-CH3
(again where the remainder of the chain is behind the page)
make a model to see how this works
a)boiling point
this is bulk property and will be the same for the two isomers
b)optical rotation
(if we are talking about specific rotation) this will be equal but with opposite signs.
c)solubility in hexane
same
d)density
a bulk property so the same
e)solubility in (S)-3-methylhexane
f)dipole moment
Same. (If it was different you could separate them by distillation)
g)taste
there may be a difference as taste buds are chiral.
b,e,g
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