Chemistry Stack Exchange
Chemistry Stack Exchange

Questions tagged [stereochemistry]

Applicable to questions about the spatial arrangement of atoms in a molecule and how they affect its physical or chemical properties.

Tag usage

This tag should be used on questions such as (but not limited to):

  • The properties of stereoisomers, both enantiomers and diastereomers (see also: and )
  • The nomenclature of such isomers according to Cahn-Ingold-Prelog rules or other conventions (e.g. +/-, ᴅ/ʟ) (see also: )
  • The study of different conformations of a molecule (see also: )
  • Particular spatial arrangements of atoms required for a reaction to proceed (see also: )
  • The creation of new stereoisomers in a chemical reaction (see also: and )

Definition

Stereochemistry is the discipline of chemistry which describes the relative spatial arrangement of atoms in molecules.

Further reading

Stereochemistry is a concept most commonly encountered in the field of organic chemistry, and aside from the usual major textbooks, a classic reference is Eliel's Stereochemistry of Organic Compounds. However, it is equally applicable to inorganic compounds and is well-described in all major textbooks.

839 questions
23
votes
2 answers

Why don't trigonal S and P compounds undergo inversion at room temperature?

Most molecules containing nitrogen atoms in trigonal pyramid configuration undergo a relatively fast process of inversion at room temperature. On the other hand, the free energy barrier for phosphines, sulfoniums and sulfoxides are high enough that…
F'x
  • 23,671
  • 8
  • 95
  • 151
18
votes
2 answers

How do I determine the absolute configuration experimentally?

Let's say I synthesized or isolated a chiral molecule and want to know the absolute configuration (R or S) of that molecule. I could obviously solve the structure by X-Ray crystallography, but that's a lot of work and I might not want to do that or…
Mad Scientist
  • 6,123
  • 2
  • 37
  • 61
9
votes
3 answers

What is the difference between configuration and conformation in stereochemistry?

I understand conformation to be any spacial arrangement of atoms that can be achieved through rotation of a single bond. I understand configuration to be the disposition of atoms/groups in space. However, would a conformational isomer also be a…
RobChem
  • 9,784
  • 34
  • 84
  • 143
8
votes
1 answer

1,2,3-Trimethylcyclopropane stereoisomers

1,2,3-Trimethylcyclopropane has two stereoisomers. When one of the methyl groups is above the plane and other two are below the plane, then there are two chiral centres as well as a plane of symmetry. By definition this compound should have a meso…
Shodai
  • 973
  • 2
  • 15
  • 26
7
votes
1 answer

Achiral universe - asymmetric synthesis

Would it be somehow possible to conduct asymmetric synthesis if all chiral molecules would exist only as racemates in nature?
EJC
  • 14,302
  • 15
  • 67
  • 157
7
votes
2 answers

Is there a plane of symmetry in [Ma3b2c]?

We have been taught to look for plane of symmetries in inorganic complexes. If there is a plane of symmetry then the complex is optically inactive, otherwise it is optically active. In this particular complex, I am unable to find the plane of…
Hdje
  • 127
  • 4
4
votes
4 answers

Number of stereoisomers and symmetry of pentane-2,3,4-triol

The answer is apparently 4, but the solution does not make sense. I can only identify 2 chirality centers (the central carbon cannot be a chirality center) so I thought 2^2 = 4 stereoisomer possibilities, but because of the existence of a plane of…
phi2k
  • 1,441
  • 6
  • 20
  • 39
4
votes
1 answer

How are the Cahn-Ingold-Prelog rules applied to chiral molecules without a stereogenic carbon center? i.e biphenyls and allenes

It's easy to apply CIP rules to chiral carbons but what about in chiral molecules without these carbon cneters like biphenyls, sulphoxides and allenes? Are they applied at all?
RobChem
  • 9,784
  • 34
  • 84
  • 143
4
votes
1 answer

R or S configuration?

The respective configutations of a and b are...? I tried to find the answer for a (for me is: 2S, 3S) but I'm not sure of my results, can someone help me?
Silvia95
  • 129
  • 6
4
votes
1 answer

How is chirality center defined for an atom with 5 substituents?

I understand that carbon atoms normally only have up to 4 substituents and the R and S chirality centers are defined for 4 substituents. Is there a similar convention of 'chirality' for an atom with 5 substituents? The SMILES website (section 3.3.4…
nos
  • 159
  • 5
4
votes
2 answers

Number of stereoisomers of trisubstituted cyclopentane

When 4-methylcyclopent-1-ene reacts with bromine, then 1,2-dibromo-4-methylcyclopentane forms. And I am stuck on determining the amount of stereoisomers that can form as a result. 1,2-dibromo-4-methylcyclopentane has two chiral carbon atoms, those…
Tim
  • 43
  • 4
3
votes
1 answer

Is this analogy explaining the difference between enantiomers and diastereomers correct?

I tried writing an analogy to explain the difference between enantiomers and diastereomers. However, I'm not entirely sure if it's actually a correct representation of the differences. It might also be more confusing than it has to be: To use an…
Threethumb
  • 207
  • 2
  • 6
3
votes
1 answer

In 2-bromo cyclohexanone,why bromine prefers to occupy axial rather than equatorial position?

I read that the substituents generally tend to occupy equatorial position rather than axial because diaxial interactions make the molecule unstable. But why is 2-bromocyclohexanone an exceptional case? I also read that it’s because of the dipolar…
Shakti
  • 135
  • 12
3
votes
2 answers

"Asymmetric molecules are necessarily polar"

Is a molecule with no symmetry necessarily polar? Can a polar molecule still have some elements of symmetry (i.e. mirror image is the same as itself)? I think so ... because we can have achiral tetrahedral carbon molecules that are polar - i.e.…
Dissenter
  • 18,815
  • 49
  • 177
  • 341
3
votes
2 answers

Diastereomers - cyclic compounds

Why in this problem there isn't a diastereomer with the $\ce{-CH3}$ in the back (dash) and the $\ce{-CH2CH3}$ in front (wedge)?
Silvia95
  • 129
  • 6
1
2 3 4 5