Isomers which can be interconverted by rotation around a single bond. These typically have a very low energy barrier to interconversion.

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Most stable conformation of aldehydes and ketones

Why is the most favorable conformation of ketones and aldehydes the one where the alkyl group is anti to the other alkyl group (or hydrogen atom in an aldehyde) as attached? Why isn't more stable the ...
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24 views

Calculation of the lowest energy conformation with a webbased solution or freeware

I like to draw a molecule in different conformations in a) website or b) freeware and Calculate its relative energy difference (for example to the lowest global energy conformation) Display the ...
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3answers
196 views

Is there a definition of rotatable bond?

Some intramolecular bonds are rotatable in the sense that the torsion angle around this bond is flexible (for example, $\psi$ and $\phi$ angles in a protein backbone). Others are essentially fixed ...
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125 views

Trying to understand SMILES(?) patterns

In the example calculation from the conformer search package fafoom is a mysterious pattern that I'd like to understand. The SMILES code of the given example structure is: ...
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50 views

Determining chirality after considering conformational interconversion in a cyclohexane

Basically I want to know what does the question mean when it says "taking into consideration conformational interconversions." I assume it means, when I draw the mirror image of the given compound, ...
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51 views

How big is the gauche interaction of methyl with phenyl in a disubstituted cyclohexane?

I'd like to compare the equatorial 1-Methyl-2-phenyl-cyclohexane conformation of with axial conformation of 1-Methyl-3-chloro-cyclohexane conformation. In which molecule there is less steric ...
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63 views

Is there an A value for the carbaldehyde and vinyl groups?

A methylene ($\ce{=CH_2}$) group ist sterically less hindered than a methyl ($\ce{CH_3}$) group. I'm wondering if the carbonyl ($\ce{C=O}$) group is sterically more or less larger than a methylene ...
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61 views

Carbohydrate conformations

I have to questions regarding the conformations of carbohydrates. There are 38 different conformations for an aldohexose or ketohexose, including $\alpha$ and $\beta$ anomers, namely 2 chairs, 6 ...
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56 views

Which of the five conformers of propyl propanoate is most stable?

I've worked out five different conformations of propyl propanoate: I think the bisected conformations (E) should be the most stable one. Are my rationals & suggestions in my scheme correct?
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200 views

Conformations of Cyclohexane

Is there any such thing as a twist chair conformation? Also, the boat and the chair conformations are achiral, while the twist boat conformation of cyclohexane is chiral and dissymetric. What about ...
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65 views

Why do sp2 carbons tend to prefer eclipsed conformations whereas sp3 carbons prefer staggered

I am a second year undergraduate and have come across this when studying stereochemistry and conformations and have been unable to find a satisfactory answer. I know that $\ce{sp^3}$ carbons prefer ...
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43 views

Energy of Eclipsed Interactions

I am asked to identify the highest and lowest energy conformations for the following bond-line structure (I think it is 2,2-dimethylbutane). I drew a Newman projection (for all 6 conformations) and ...
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Ground state conformation of dimethyl disulfide

What is the ground state conformation of dimethyl disulfide ? The two which seem reasonable to me are trans to avoid methyl-methyl gauche interactions or gauche due to sulfur donation into the S-Me ...
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155 views

Assign the configurations of the stereo centres in (-)-menthol and (+)-neomenthol?

I have to assign R or S to the chiral centers in (-)-menthol and (+)-neomenthol. The results I got are shown below in the picture. However, when I looked on Wikipedia to check my answers they ...
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1answer
120 views

Conformational analysis determining forces

So the determining forces in the conformational analysis (what will be the more stable state and what will be the more excited state) according to my textbook are: Steric interaction Electron ...
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113 views

IBrF2 - van der Waals repulsions - and number of unique bond angles

I understand that the molecule $\ce{IBrF2}$ is T-shaped, with three ligand atoms and two non-bonding pairs. However, how many unique bond angles can this molecule exhibit? My professor argues for ...
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92 views

How to calculate the frequency of cyclohexane conformational interconversion?

My book mentioned that the energy barrier for cyclohexane to reach the half-chair conformation is 50.6 $\text{kJ mol}^{-1}$. It says that from this value, it was calculated that cyclohexane undergoes ...
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333 views

Covalent bond deformation

When do covalent bonds of a molecule $M$ extend or compress while no bonds in $M$ are broken? I can conceive of some possibilities but I don't know how common they are: Temperature changes ...
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331 views

Which is most stable conformation of optically inactive butane-2,3-diol?

The most stable conformation of optically inactive butane-2,3-diol is: (A) (B) (C) (D) I choose C as the correct answer but, in the answer key it given to be B. C is the staggered form and the ...
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752 views

Solvation effect on cyclohexane

I ran molecular dynamics simulation with a molecule of methylcyclohexane soaked into a water box. On the other hand I ran Monte Carlo with the molecule alone (no soaking). I performed this for the ...
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256 views

Methylcyclohexane chair conformers

I am trying to create the molecule of the methylcyclohexane in the equatorial and axial conformers. I read in this site about the chair conformation. My molecule looks like the following picture ...
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1answer
199 views

Percentage of a conformer in vacuum

I just started with Molecular dynamics simulations. My background is computer science but I'm learning about scientific computing and thus my jump into MD. Having said that, I was asked to calculate ...
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3k views

Which conformer of Beta D-glucose is more stable

I drew the two chair conformers of Beta D-glucose: Which one is more stable? I think it's the one with all of the OH groups in the equatorial position because of less steric hindrance, but I also ...
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159 views

Rotation energy barrier for carboxypyrazolate

In this molecule, which is 3,5-dimethyl-4-carboxypyrazolate (unless I got it wrong): I do not think there is free rotation around the bond indicated in red, because one can write a resonance ...
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657 views

Effect of periodic acid on cyclohexane derivatives

Periodic acid (per-iodic acid, $\ce{HIO4}$ ) cleaves vicinal diols(to carbonyls) via a cyclic intermediate. Due to the cyclic intermediate, it needs a syn configuration for the $\ce{-OH}$ groups for ...