Skip to main content

Questions tagged [stereochemistry]

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

122 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
8 votes
0 answers
2k views

Tables/database/literature of specific or optical rotation

I'm looking for a comprehensive reference of experimental specific rotation or optical rotation data. It can be a published literature review, a free web database with API access or one that permits ...
pentavalentcarbon's user avatar
7 votes
0 answers
369 views

What compound has the strongest optical rotation of polarised light?

A question recently asked here whether compounds know to be chiral can have non-measurable optical rotations: Are there chiral compounds that don't rotate plane-polarized light?. Apparently they ...
matt_black's user avatar
5 votes
0 answers
68 views

Does PubChem have stereocenter location data?

I have spent the last couple of days learning to navigate, find useful information and use the download service on the PubChem website. One of the pieces of information you can find is a stereocenter ...
Dragonoverlord3000's user avatar
5 votes
0 answers
115 views

Type of chirality in polycyclic compounds

Ignoring whether or not this molecule could exist, is there a name for this type of chirality? This molecule's mirror image cannot be superimposed on itself but there are no chiral centres. Even ...
hazza_h's user avatar
  • 51
5 votes
0 answers
79 views

Is it possible to estimate the abundance of conformers from J values?

I have a system of two disubstituted cyclohexanes and I want to estimate the abundance/ratio of the two based on the J values and if possible, roughly estimate the difference in free energy. To get ...
flippinpippin's user avatar
5 votes
0 answers
162 views

Endo/Exo for same length bridges

I'm looking at a cycloaddition that produces a bicyclic intermediate, there are two different ways of doing the addition which can be described as endo/exo. However, all three bridges are the same ...
DSVA's user avatar
  • 5,792
5 votes
0 answers
203 views

Asymmetric Suzuki coupling - saturated alkyl chain

9-BBN is applied for Suzuki coupling of a saturated alkyl chain with some alkenyl,alkynyl or even secondary alkyl halide like the modification attached: (Saito, B.; Fu, G. C. Alkyl−Alkyl Suzuki Cross-...
EJC's user avatar
  • 14.4k
5 votes
0 answers
707 views

Using CIP rules in a bicyclic compound with carbonyl subsituent

In bicyclo[2.2.1]heptan-2-one, arrange the numbered groups according to CIP rules: Group 1 will have highest priority because oxygen atom is attached to 1. (It can be considered as two oxygen atoms). ...
Aditya Dev's user avatar
  • 7,826
4 votes
0 answers
265 views

Is There a Problem with the Assignment of Stereochemical Descriptors by ChemDraw in Select Examples?

While using ChemDraw Professional 21.0.0.28 to construct some cyclic allenes and rotationally restricted biphenyls, I came across anomalous assignments of stereochemistry. [For the latest version of ...
user55119's user avatar
  • 17.1k
4 votes
0 answers
51 views

Is optical activity of a given compound a statistical picture?

When optical activity is taught it is done in terms of single molecules. But when it is actually measured it is done on a large collection of such molecules. So, how does the asymmetry manifest itself ...
Swaroop Chandra's user avatar
4 votes
0 answers
148 views

[3+1]-Cycloadditions of Sulfur Ylides and 1,3-Dipoles(?)

My question is basically regarding the stereoselectivity of the situation. I am not being able to decide on the positioning of the sulfur ylide with proper justification. In the attached hand-drawn ...
Eashaan Godbole's user avatar
4 votes
0 answers
355 views

Examples of intramolecular hydrogen bonding closing bond angles

Okay, we've established that intramolecular hydrogen bonding can exist in molecules, and doesn't always serve the purpose of closing the bond angle at least relative to other stereoisomers of the same ...
Dissenter's user avatar
  • 19k
4 votes
1 answer
289 views

Why is the A-value of methoxy group lower than that of the hydroxyl group?

I am studying conformational analysis of monosubstituted cyclohexane. "A-value" refers to the energy difference between conformers with substitutent in equatorial (more favored) and axial ...
Ray Bradbury's user avatar
4 votes
2 answers
1k views

Determining the stereochemistry of the product(s) when an alkyl shift in a carbocation generates a chiral carbon

Consider this carbocation: We know that this carbocation would immediately rearrange - by a methyl shift - to form the more stable carbocation. Now, notice that the migration will produce a chiral ...
Gaurang Tandon's user avatar
3 votes
0 answers
37 views

Systematic method to determine D/L notation of substances other than amino acids and glyceraldehyde

The fundamental rules of D/L notation, as I understand it, are as follows; In D/L notation, a molecule is named by mapping it to glyceraldehyde. The D/L notation is based on the stereo configuration ...
Blue Various's user avatar
3 votes
0 answers
52 views

To what extent should a question such as: "how many enantiomers are there?" take geometric isomerism into account?

Pretty simple question here. How many enantiomers are there for the structure $\ce{CH3CH=CHCH(CH3)CH2CH3}$? On the one hand, there is just one chiral centre so one would suggest $2$. On the other ...
FShrike's user avatar
  • 223
3 votes
0 answers
53 views

Optical activity of (1r,3R,5S)-1-methyl-3,5-dipropylcyclohexane (or other long alkyl groups)

Consider a cyclohexane with a methyl group at C1 position and a propyl group at C3 and C5 position and each of the first bond bonded to the cyclohexane in alkyl groups has wedge bond. I do not think ...
làntèrn's user avatar
  • 639
3 votes
0 answers
112 views

Assigning configuration of chiral plane - selecting of the pilot atom

I am little confused about when it comes to assigning configuration of planarly chiral cyclophanes - and I think it comes down to selection of pilot atom. All sources I have came across say that the ...
Fractal's user avatar
  • 402
3 votes
0 answers
42 views

Labelling of molecular motor isomeric forms as trans and cis

I am reading Koumura et al. (2002), a paper about molecular motors. It contains this figure: Being an absolute layman when it comes to naming my molecules I'm a little confused as to why the left ...
Heatherfield's user avatar
3 votes
0 answers
71 views

Does optical isomerism fall under the category of stereoisomerism?

I have been asked to find the total number of dichlorination products (including stereoisomers) for the following reaction: I have figured out nine possible structures out of which two are optically ...
Aniruddha's user avatar
  • 462
3 votes
0 answers
216 views

Fischer's projection, enantiomers and diastereomers

Given Fischer's projections of a few stereoisomers of some compound, how can we find out if they are enantiomers, diastereomers, etc.? From what I understand, we can rotate the projections to have the ...
Raghavendra Singh's user avatar
3 votes
0 answers
114 views

What happens when tran-2-butene reacts with aqueous bromine in the presence of chloride?

$\ce{Br2-H2O}$, containing some $\ce{NaCl,AlCl3}$ ? I initially though that there would be anti addition of Br and OH to give 3-Bromobutan-2-ol but then I also got the intuition that NaCl might ...
Prajwal Tiwari's user avatar
3 votes
0 answers
133 views

Stereochemistry of the product of crotonic acid with bromine

Is there a a simple rule for determining the stereochemistry for the product of a reaction between an unsymmetrical alkene like (2E)-but-2-enoic acid and bromine (anti reaction)? If it's an anti ...
Sharbel Damouni's user avatar
3 votes
0 answers
584 views

What do γ (gamma) and λ (lambda) mean in organic chemistry?

From the Wikipedia entry on Cyhalothrin: Pyrethroids such as cyhalothrin are often preferred as an active ingredient in agricultural insecticides because they are more cost-effective and longer ...
Kurt Hikes's user avatar
  • 1,795
3 votes
0 answers
125 views

Chemical shift difference methyl groups in 4-hydroxy-2,5-dimethyl-3-hexanone

Can someone explain why the NMR Spectrum of 4-hydroxy-2,5-dimethyl-3-hexanone shows a chemical shift difference for the methyl groups at the end? Why aren't the other carbons have a difference? Below ...
Gesetzt's user avatar
  • 53
3 votes
0 answers
485 views

Why does Pubchem show cis-1,3-cyclohexanediol with the hydroxyls in the equatorial position?

I am a beginning organic chemistry student and trying to reason about something based on information in my book, but seeing that Pubchem gives a different structure than I'd expect. In considering a ...
Katie's user avatar
  • 289
3 votes
0 answers
100 views

How to apply the parvo/amplo akamptisomeric stereodescriptors to this bicyclic system?

I'm looking for examples of akamptisomerism[1]. I'm try to find simple molecules able to (theoretically) show this kind of isomerism. I thought about the isomers of (2R)-2-methyl-9-oxabicyclo[3.3.1]...
grsousajunior's user avatar
3 votes
0 answers
1k views

Retention of configuration in Hofmann rearrangement

Why is there a retention of configuration in Hofmann bromamide degradation/Hofmann rearrangement? I would think that there should be an inversion of configuration due to the migration of alkyl group ...
user600016's user avatar
  • 1,027
3 votes
0 answers
175 views

effect of different groups on Amine inversion

I know different groups attached to the nitrogen atom affect the amine inversion barrier, but is it due to steric factors or orbital interaction factors, eg. $\ce{(i-Pr)2NMe}$ vs $\ce{NCl3}$.
Sourav Singh's user avatar
3 votes
0 answers
92 views

In an electrocyclic reaction with two pi bonds that result in a trans product, is a mix of products seen?

When I look at the highest occupied molecular orbital, the two methyl groups will end up being trans to each other. I realized based on which conrotation direction both methyl groups take that two ...
Biomed Boy's user avatar
3 votes
0 answers
287 views

What symmetry elements mustn't a molecule possess to be considered achiral?

Undergraduate textbooks say that a molecule mustn't posses a reflection plane and an inversion center to be considered achiral. As mentioned by Ron in his answer to this question, molecules that don't ...
EJC's user avatar
  • 14.4k
3 votes
0 answers
270 views

Assigning R/S stereochemistry of a cyclic molecule

I've been dealing with assigning stereochemistry and I seem to be doing okay, but I've come across a molecule that I've found a little tricky to deal with. I've identified three stereocentres, ...
ConfusedStereoChemist's user avatar
3 votes
0 answers
2k views

Entropy and racemization?

The process of racemization of an optically compound is entropy driven and hence nature prefers a racemic mixture to an optically active one, which is consistent with the idea of the intuitive ...
stochastic13's user avatar
  • 6,795
2 votes
1 answer
83 views

How to determine the value of the NOE from the NOESY spectrum?

I have 1D NOESY spectra from which I need to find out the value of the NOE (%). Is it enough to simply measure the intensity of the resulting peaks or is it necessary to subtract it from the ...
Klee's user avatar
  • 21
2 votes
0 answers
99 views

Is there a formal definition of “identical” molecules?

I was reading about atropisomers and their impacts on drug design, and I started wondering whether we have a formal definition for identical molecules. Atropisomers are not the same molecules because ...
Akash's user avatar
  • 335
2 votes
0 answers
130 views

stable conformation of 2,3-dimethylsuccinic acid

I was researching for answering this question on Kolbe's electrolysis of 2,3-butanedicarboxylic acid (succinic acid). Turns out, this compound is not very well researched in particular, and shows few ...
ananta's user avatar
  • 2,307
2 votes
0 answers
610 views

Is hydroxylamine monodentate or ambidentate ligand?

What is the total number of geometric isomers of the complex $\ce{[Pt(Cl)(py)(NH3)(NH2OH)]+}$? If $\ce{NH2OH}$ acts as an ambidentate ligand, then there should be six geometric isomers. Or is it ...
Ritesh 's user avatar
2 votes
0 answers
115 views

Can endo and exo products occur when the diene is not cyclic?

I have always thought that the diene needs to be cyclic for there to be endo and exo products. Perhaps, I formed this impression because most textbook examples that are used to illustrate the concept ...
Tan Yong Boon's user avatar
2 votes
0 answers
36 views

Sn(II) compound stereoselectivity in aldol reactions

In "advanced organic chemistry: part B" fifth edition, page:130, the authors state that chiral proline-like additives to Sn(II) compounds can further increase stereoselectivity of aldol ...
mohamed's user avatar
  • 565
2 votes
0 answers
201 views

(How) can a reaction be both stereoselective and stereospecific?

From what I have learnt, stereospecific and stereoselective reactions are defined as follows - Stereospecific - The stereochemistry of the reactant dictates the stereochemistry of the product. Thus, ...
TRC's user avatar
  • 1,817
2 votes
0 answers
47 views

Solvent shell collapse

In "advanced organic chemistry part A" book page:306&307 , the author uses the term 'solvent shell collapse' when talking about the reason for retention of conformation in tertiary ...
mohamed's user avatar
  • 565
2 votes
0 answers
104 views

Strains in conformations of cyclohexane

I know some the basic kind of strains that can exist in molecules namely Torsional strain (Vanderwaals' strain), steric strain and angle strain. Is it possible to associate a particular type of ...
Chem-Learner's user avatar
2 votes
0 answers
1k views

Find stereo isomers of camphor

The compound given is camphor: We have to find the total number of stereoisomers for this compound. Now I can see two chiral carbons so I thought the number would be $4$ but it turns out that there ...
infinite-blank-'s user avatar
2 votes
0 answers
84 views

Differences in efficacy of oxime reactivators in organophosphate poisoning

Compounds containing an oxime functional group, such as 2-PAM and obidoxime, are used in the treatment of poisoning with organophosphorus compounds. These oximes reactivate the enzyme ...
user73910's user avatar
  • 1,264
2 votes
0 answers
425 views

Shortcuts for finding geometrical isomers

Our teacher provides us extra questions for pratice, so one of the questions was :- Find number of products if following are reacted with excess $\ce{NH2OH}$ (hydroxyl amine): Cyclohex - (i) 1,4-...
aryan bansal's user avatar
2 votes
0 answers
59 views

Finding out more stable conformer via molecular orbital interaction

Out of these two, which one is more stable? I'm unable to imagine the orientation of the lone pairs of O and ABMO of C and Cl bond. Any tips to tackle these kind of problems?
user_9's user avatar
  • 203
2 votes
0 answers
48 views

Name of the intermediate in between phosphono and phosphonato group

$\ce{R-PO3^2-}$ is called a phoshonato group (https://www.ebi.ac.uk/chebi/searchId.do?chebiId=30931) $\ce{R-PO3H2}$ is called a phosphono group (https://www.ebi.ac.uk/chebi/searchId.do?chebiId=48108) ...
Anonymous Faculty's user avatar
2 votes
0 answers
221 views

Why do tetrahedral organic molecules show stereo-isomerism, but not tetrahedral transition metal complexes?

Both types of molecules show different arrangements of the molecule in space, so they should qualify for optical isomerism right?
madeye moody's user avatar
2 votes
0 answers
224 views

What does the dissociative mechanism for cis/trans interconversion of [Mo(CO)4(PPh3)2] look like?

All I can find in the literature is that the cis→trans interconversion proceeds via dissociation of one of the PPh3 ligands resulting in a square-pyramidal Cs intermediate, with the remaining PPh3 in ...
Funk's user avatar
  • 91
2 votes
0 answers
372 views

Does dihydroimidazole show geometrical isomerism?

Does dihydroimidazole (above) exhibit geometrical isomerism? Does the fact that the lone pair is involved in conjugation with a double bond affect anything? As far as I know, it does not exhibit ...
stoic-santiago's user avatar