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Questions tagged [conformers]

For questions about conformational isomerism. Use this tag alongside [stereochemistry].

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1answer
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Bond rotation in buta-1,3-diene

Why don't all the atoms in s-cis-1,3-butadiene lie in one plane? All carbon atoms are $\mathrm{sp^2}$ hybridised and I feel that there would be no $\ce{C-C}$ bond rotation due to the conjugation ...
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1answer
69 views

Conformer generation for radicals

Is there an automatic way to generate conformers for radical like systems (spin multiplicity is doublet)? My system for the study is a substituted fullerene with a missing H atom from the functional ...
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64 views

Conformation isomers

I read that conformers have different configuration due tomorrow rotation of a molecular with respect to an axis. I have a doubt regarding the classification of conformers into staggered,eclipsed,...
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1answer
35 views

Trouble with Converting from Structural Formulas into Newman Projections

I have the following question from my Organic Chemistry textbook: I'm asked to convert the following line diagram into a Newman Projection. The arrow pointing to the carbon signifies "looking down ...
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0answers
133 views

Staggered and Eclipsed conformations of n-butane?

If we are only talking about staggered and eclipsed conformations then , I am finding 4 conformations , but the answer given for a question has the answer as 6 .These are the four conformations I am ...
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2answers
175 views

What is the most stable conformation (Newman Projection) of CF3CH3?

Is a totally eclipsed Newman projection the most stable conformation for a 2 carbon compound, with one carbone bonded to more electronegative atoms (making them partial negative), and the other carbon ...
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2answers
173 views

why does ring flip of L-fructose occur?

when drawing the chair conformation for beta-L-fructose, I got the structure above (in the picture). The answer said that the conformation above had a ring flip. Why does a ring flip occur and how can ...
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0answers
190 views

Cyclohexene conformation in fused ring

The picture (a) is from a organic chemistry book by Clayden, Chapter 32. That means drawing (a) is right expression of the molecule. What I wonder is that is it possible for (a) to ring-flip? If so, ...
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2answers
417 views

Hyperconjugation in ethane conformers

I refer you to this set of presentation slides. On slide 8, the author explains the preference for the staggered conformation of ethane by saying that there is a favourable hyperconjugative ...
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2answers
955 views

Why are conformational isomers considered as isomers?

I was taught that geometric (cis-trans) isomers are considered isomers because there is a high energy barrier to breaking the double bond for rotation (to convert into the other isomer). Given that ...
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1answer
251 views

Atropisomerism of naphthyl alcohol

In March's Advanced Organic Chemistry (6th ed.), it's stated that the above two are atropisomers. I don't get why is it so. How is the topmost $\ce{C}$ locked in its place? Surely, there's steric ...
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1answer
774 views

Dipole moment of ferrocene conformations

Which conformation of ferrocene has a zero dipole moment? I thought that the answer should be the staggered conformation because it would have the cyclopentadienyl groups oriented away from each ...
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1answer
330 views

Is there a way to determine the orientation of a benzene-ring ethyl group in synthesis reactions?

On my study guide for synthesis reactions (specifically for the synthesis of disubstituted benzene derivatives), two of the problems look extremely similar. The question on the guide asks us to ...
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1answer
257 views

What is the correct way to notate conformation preferences of polysaccharides?

In some webpages (1 or 2) are found the way to notate the conformational preferences of monosaccharides such as furanose and pyranose. But, it lacks to give a brief description on how to do it with ...
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1answer
162 views

Reason for the greater energy of the eclipsed conformer of alkanes?

My textbook says this: "In the staggered form of ethane, the electron clouds of C-H bods are as far apart as possible, thus there are minimum repulsive forces, minimum energy and maximum stability. On ...
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2answers
344 views

Any program for conformational searching for sugars?

I want to estimate mean Gibbs free energy of formation of glucose and for that purpose I think conformers of ring flip should be taken into account. Do you know if some free program can find those ...
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1answer
79 views

Estimating standard Gibbs free energy of a molecule

When trying to estimate the standard Gibbs free energy of a molecule at room temperature and normal pressure, we can use Maxwell Boltzmann average over its rotational conformers. My doubt is the next ...
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1answer
67 views

How to determine the dimensions of a bixin molecule?

I need the dimension of a bixin molecule. I do not know where to look or how to calculate this information. I understand that this molecule has several rotational axes and conformation, so there is ...
4
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1answer
66 views

Could chromatography induce a conformational change?

We'd been studying chromatography in our instrumental analysis course and I was wondering if chromatography could induce a conformational change. For example, you have a straight chain with a ...
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1answer
87 views

Why is the boat form of paraldehyde not theoretically possible?

Wikipedia says the following about paraldehyde: Theoretically, four stereoisomeric structures are possible. The structures (1) and (2) are known as cis- and trans-paraldehyde. The structures (...
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2answers
2k views

If α-glucose is less stable than β-glucose, why is glucose almost always α in its compounds?

Maltose, saccharose, turanose, trehalose, trehalulose, amylopectin, amylose - they are all α. Why? Also, why is cellulose β?
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2answers
90 views

lowest energy conformation of butan-2,4-diol

Do the OH groups want to be furthest apart? or the CH3 groups? I'm trying to determine the lowest energy conformation - and I don't know which group has the bigger steric effect?
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0answers
38 views

Torsional Potential in 1,1,2,2-tetrafluoroethane

Considering $\ce{CHF2-CHF2}$ (ethane from which 4 hydrogen atoms have been substituted by fluorine ones) I am asked to propose a torsional potential, taking into account that stretching and bending ...
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4answers
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Five-pointed crown alkane C25H40: does it exist?

My 4 year old granddaughter, playing with molecular models, began making a cyclopentane ring, each of whose carbons bore a spiro-connected cyclopentane ring of its own , in the manner of spiro[4.4]...
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2answers
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Why is the cis isomer of 1,3-dimethylcyclobutane more stable than the trans isomer?

I expect there to be more steric repulsions between the two methyl groups if they are on the same face as each other. Why is this not the case?
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0answers
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Workflow for many-molecule/many-conformer calculations in Spartan, GAMESS, AND Gaussian

I wish to investigate the antioxidant properties of several hydrocarbon compounds, which are each mono- or polyhydroxylated, specifically at the phenyl ring. I wish to gain insight into my workflow ...
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1answer
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Is the SN1 reaction faster with an axial or equatorial leaving group?

Why does compound 1 undergo the $\mathrm{S_N1}$ reaction faster than 2 even though both proceed via the same carbocation intermediate?
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2answers
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Conformation of Alkane - Which conformations of 2,3-dimethylbutane are more stable?

I am not sure what the proper arrangement of these conformations are from least to most stable. My thinking was this...(but I got the wrong answer). First, I thought that because 2 and 4 are in ...
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0answers
140 views

Confusion about gauche effect

This recent question about the gauche effect led me to read this rather older answer. The problem is that I notice I am still confused. To take the case of 1,2 difluoroethane, I drew these orbitals: ...
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460 views

Why is gauche conformer of 2,3 dimethyl butane more stable than its anti conformer?

Why is gauche conformer of 2,3-dimethylbutane seen along 2,3 bond more stable than its anti conformer? It seems to be anomalous to me as in most other butane like compunds anti form is more stable ...
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1answer
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Multiplet shape in proton NMR of morpholines

I recently carried out a Buchwald–Hartwig reaction to attach a morpholin-4-yl group to an aromatic ring: In the proton NMR of the (columned) product, I found the peaks corresponding to the morpholine ...
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1answer
3k views

Cyclopentane conformations

What is the energy minimum of cyclopentane conformational diagram: the halfchair or envelope? How does cyclopentane flip?
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1answer
199 views

What are the implications of having different conformations?

I have seen videos explaining what conformations are. I am curious about whether different conformations can give rise to slightly different properties. Particularly of interest is whether you can ...
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2answers
3k views

Hydrogen bonding in staggered vs eclipsed conformations

In my first semester of organic chemistry, we learned that staggered conformations have lower energy/higher stability. However, my thought is that if you have interacting OH groups, the hydrogen ...
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1answer
4k views

Energy profile of cyclohexene conformations

The energy profile for cyclohexane flipping looks like this: How does the corresponding diagram for cyclohexene look like?
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3answers
821 views

Conformation of six-membered ring constituting a bridged compound

What is the conformation of the cyclohexane ring constituting [2.2.1]-bicycloheptane? Is it boat or twisted boat? Is that conformation abundant in other bicyclic systems containing a cyclohexane ring?...
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2answers
3k views

Relative rates of two acyclic dienes in the Diels-Alder reaction

As for factors that affect the rate of the Diels Alder reaction, having an s-cis conformation is primary. But in a case as shown below, what makes the second diene react faster compared to the third? ...
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1answer
585 views

Enolate formation and tosylate displacement in cis/trans decalin

What will happen in the following reactions? This is Problem 3d from Chapter 6 of Zweifel and Nantz's Modern Organic Synthesis. I thought that after the hydroxyl group is converted into a good ...
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2answers
3k views

Why is the eclipsed conformer more stable than the bisected conformer in 1-butene?

I have just started learning conformational analysis, and a major doubt came into my mind. In simple alkanes such as ethane, the staggered conformer is much more stable than the eclipsed conformer. ...
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2answers
263 views

drawing epoxides, the 3d shape

given the image on the left, when you look at it from the side would it look like the image in the right? since the thicker lines means it's coming out of the page?
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1answer
835 views

Energy of eclipsed and staggered conformations of ethane and propane

Which points on the given energy diagram represents eclipsed confirmation of ethane and staggered confirmation of propane respectively? Attempt: Eclipsed configuration is unstable because of ...
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1answer
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Does trans 1,3-dichlorocyclobutane have zero dipole moment?

Does this compound have zero dipole moment? I think it has a non-zero dipole moment. If I assume the ring to be planar, then the dipole moments of each $\ce{C-Cl}$ bond cancel out. (One is upward and ...
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1answer
3k views

How can the gauche-effect be explained?

Generally, anti-conformations are more stable. But in the case of 2-fluoroethanol, the gauche confirmation is more stable. It's given in March's advanced organic chemistry book that intramolecular ...
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1answer
114 views

Conformation identifying cis and trans

How to identify cis and trans in conformers of cyclo hexane.i know that there are two positions axial and equatorial but using this data how to identify cis or trans? Also why are functional groups in ...
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2answers
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What is the difference between steric strain and torsional strain?

I know that in ethane, the extra energy present in the eclipsed conformer is caused by torsional strain. In butane, the gauche conformation experiences steric strain. But the eclipsed conformation ...
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1answer
1k views

When can a molecule be considered freely rotating at room temperature?

This question sparked from a long discussion in chat about the nature of $\ce{H2O2}$ and whether that molecule can be considered to rotate around the $\ce{O-O}$ axis (and hence display axial chirality)...
5
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1answer
944 views

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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1answer
1k 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
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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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1answer
306 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: ...