Questions tagged [stereochemistry]

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

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Isomerism , Geometrical isomerism basic concept [closed]

Geometrical isomerism is molecule having same molecular formula, same molecular weight but differ in arrangement of atom/group in 3D space which arises purely because of the "hindered rotation" around ...
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Number of stereoisomers of polysubstituted cubane

The molecule given below is a substituted cubane. a) How many stereoisomers exist for this molecule? b) How many pairs of enantiomers are possible? How do I calculate the number of ...
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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?
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What is the number of stereoisomers for hex-4-en-2-ol?

For the following compound, find Total number of stereoisomers Number of optically active stereoisomers Total number of fractions on fractional distillation of all stereoisomers ...
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2answers
89 views

Number of sterioisomers of 2,3,5,6-tetrachloroheptane [closed]

The answer given by Himanshu Pandey in the book Advanced Problems in Organic Chemistry, Chapter Isomerism, Page 76 is 10. But by calculating using the fundamental principle of counting and by viewing ...
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Stereochemistry of C as non-chiral centre

When a C of a molecule is not a chiral centre, the spatial orientation of its substituent group doesn't affect its stereochemical specification, does it? Ex:
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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) ...
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41 views

Which of the Following is Optically Active?

Which of the Following is Optically Active? I understand that for a compound to be optically active, it needs to be chiral and not have any planes of symmetry. I know 1 is symmetric, but I am ...
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86 views

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-...
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73 views

Why do chiral biological molecules only exist as one enantiomer? Does it have any advantage?

Why is it that chiral biological molecules are enantiomerically pure? The other enantiomer would have the same reactivity, and the only difference is their angle of rotation of plane polarized light. ...
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223 views

Number of optically active compounds among the products of ozonolysis

The number of optically active compound(s) obtained upon complete ozonolysis of the following optically active compound is In the question, I broke all the double bonds and added a $\ce{-CHO}$...
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How many products does this reaction yield?

How many products can we get from the monochlorination of 2,4-dimethylpentane including stereoisomerism? I have seen someone say that it yields 3 structural isomers one of which has two enantiomers ...
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Why does only the cis-isomer of potassium dioxalatodiaquochromate(III) form?

A friend of mine performed a standard synthesis reaction of potassium dioxalatodiaquochromate(III) by adding potassium dichromate to ethandioic acid dihydrate and a little water. The synthesis ...
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108 views

Synthesis of an epoxide from 1,2-diol

Why is there no formation of epoxide when the two OH-groups are on different planes? I do understand the epoxidation mechanism. However, I would be grateful if someone cleared the specific ...
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1answer
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Can someone explain 3‐(propan‐2‐yl)cyclohex‐1‐ene forming a carbocation?

Can someone explain this one, especially the formation of the secondary carbocation (in the solution)? Solution: After the electrophilic attack by $\ce{H+}$ on the π bond, I had expected the ...
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1answer
60 views

How many dipeptides are possible by the reaction of glycine and alanine?

How many dipeptides are possible by the reaction of glycine and alanine? Glycine has no chiral centre. Alanine has one chiral centre. The products are alanylglycine and glycinylalanine (I not sure ...
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1answer
57 views

What are the isomers of a complex having a structure of M(AB)2C2?

Our instructor have us answer an isomerism problem of a crystal structure that has a form of $\ce{M(AB)2C2}$. I keep getting 9 isomers, which includes the optically inactive isomer, and my peers and I ...
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What is the mechanism of the reaction of ethyl prop-2-ynoate to ethyl (2Z)-2,3-dibromoprop-2-enoate?

It's really weird for the product is 99% Z-comformation? Please tell me why? This reaction can be found in scifinder.
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Posible Pair of Enantiomers

What is the number of possible enantiomers in monochlorination of 2-methybutane? My approach When $\ce{Cl2}$ is added to any alkane it prefers $3^\circ > 2^\circ > 1^\circ$. When it is being ...
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82 views

Cahn–Ingold–Prelog Rules, cyclic structures, and breaking ties

(3S,5R)-3-ethyl-5-methylcyclohex-1-ene Does anyone know how one reaches the conclusion that the 5C is R? I tried using the Cahn–Ingold–Prelog priority rules but kept getting confused. From chem....
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1answer
66 views

Why don't ionic compounds show stereoisomerism?

When I was reading about crystalline nature of ionic compounds, I came across the statement that ionic compound doesn't show stereoisomerism. What does that mean and can anybody explain the reason ...
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Reactivity of Grignard reagent

I had the following question at an exam: What is the fastest reacting compound towards nucleophilic addition with Grignard reagent? (a) Acyl chloride (b) Aldehyde (c) Ester It is ...
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1answer
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FMO analysis of the [3,3] Sigmatropic reaction regarding geometry. Is it accurate?

While studying the reasons behind the stereospecificity of [3,3] Sigmatropic reactions, I ran into an image portraying both possible transition states for the reaction: The Chair TS and Boat TS. The ...
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How to convert wedge–dash structure into Fischer projection? [closed]

I am very confused when a compound with more than one chiral centre is given. How to find whether the two compounds are enantiomers or diasteromers? Please also explain how to convert more than one ...
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114 views

The maximum no. of isomers (including stereoisomers) that are possible on mono-chlorination of the compound: 3,3-dimethylpentane is?

The maximum no. of isomers (including stereoisomers) that are possible on mono-chlorination of the compound: 3,3-dimethylpentane is? The answer given is 5. My working: The fourth carbon is chiral ...
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1answer
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Stereochemical dichloride treatment [duplicate]

In this question there is no inversion in A to B, but there is one in C to D. I feel like this must be due to the lone pairs on the $\ce{S}$ (in A) being able to open the ring, whereas this isn't ...
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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 ...
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1answer
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Is the -OCH3 group bulky?

Our teacher told us that $\ce{OCH3}$ is a less bulky group when compared to other bulky groups like $\ce{CH3}$, $\ce{NO2}$ etc. Is this true? If yes, why?
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Cyclohexane derivative formation of carambolaflavone using a Lewis acid catalyst

The scheme below summarizes the results from a study into the optimum conditions needed for a key step in the synthesis of the proposed structure of carambolaflavone, a natural product that has ...
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Path to take when labeling R/S

I'm trying to find the R/S for the carbon marked with the asterisk. As I branched out to from the asterisk carbon to the red carbons, the methyl group has the 3rd priority (with the hidden hydrogen ...
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Planarity of given molecules in all conformations

Which of these have all its atoms in one plane in all the possible conformations (if any): A) buta-1,3-diene B) but-1-en-3-yne C) $\ce{CH2=C=O}$ D) $\ce{CH2=C=CH2}$ While I was ...
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Would Z and E isomers show different optical activity?

Consider this compound, which is in E configuration and that red asterik denotes the chiral carbon. If I were to somehow cause the E-configuration of the alkene part to Z-configuration keeping the ...
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Which of the following compounds is NOT an isomer? [closed]

Which of the following compunds is not an isomer? I cant figure out how the answer is d
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Can a double bond extend beyond the plane and if so, how would it be drawn?

Can double and triple bonds, etc., extend beyond the plane in a Lewis structure, and if so, how are they represented? I.e., how would 1 and 2 in this image be drawn if they were doubles or triples?
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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?
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method to certify the number of chiral carbons in fischer and haworth projection of glucose

While reading some notes about Glucose and its various projections: Fischer Projection: 4 chiral centres Haworth Projection: 5 chiral centres My doubt is that is there any (specific) method (...
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Confused between structural isomers versus stereoisomerism

So this question wanted me to find two cyclical compounds that are 'structural' isomers of the molecular formula given in the question. The two isomers I came up with are: 1,2-dichlorocyclopropane ...
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Cis and Trans Isomerism given three different groups around the reference plane

In the following problem I am meant to deduce the molecules that are cis-trans isomers of each other. This question does not make much sense in my head because I thought that cis/trans isomerism was ...
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What is the name of “cis/trans” isomerism when all four groups are different?

How would you call a pair of isomers on the picture below? They look a lot like regular cis/trans isomers, except all four groups are different. I can tell they are spacial isomers (stereoisomers) ...
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How are these two molecules identical?

I can see that these compounds are identical as we have basically just done a 180 degree rotation of the molecules. But if we go by the concepts of chirality, the carbons 2 and 4 are chiral centers ...
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The van't Hoff rule for stereoisomers with planes of symmetry

We know that the maximum possible numbers of stereoisomers of a molecule is given by the van't Hoff rule, which says that: $$Total \space stereoisomers = 2^{n}$$ Where $n$ is the number of ...
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Does the Location of Line-Dash-Wedge Notations Matter?

In Line-Dash-Wedge notation, when illustrating that an atom or bond is directed towards or away from the viewer (solid triangle for coming forward, dotted lines for going back), does the location of ...
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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 ...
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Why does the 31P{1H} NMR spectrum of cis-[Mo(CO)2(dppe)2] show two signals?

I've tried searching for literature references that explain this, finding only a single reference which refers to the two signals as originating from phosphine environments cis/trans to carbonyls, ...
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Why are carbons of Inositol chiral centers?

I was asked to draw all possible stereoisomers of inositol (1,2,3,4,5,6-cyclohexanehexol). To obtain the answer I had to assume that all six carbons of the molecule are asymmetric, which (bearing in ...
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2answers
472 views

Can we rotate a mirror image by any angle to check if it is superimposable? [closed]

A molecule is chiral when it is different from its mirror image, and achiral if it is identical to its mirror image. To check if the mirror image is identical to the original object, we have to check ...
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Creating a Battery using azobenzene in High School [closed]

I’m doing a project on isomerization in high school and have stumbled across the studies involving azobenzene in energy storage using its photoisomeric properties and sunlight . Do you think that this ...
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Which one has higher priority according to Cahn–Ingold–Prelog rules?

Which one has higher priority according to Cahn–Ingold–Prelog rules? (1) $\ce{-CH2OH}$ and $\ce{-CH=CH2}$ (2) $\ce{-CH2OH}$ and $\ce{-C(CH3)3}$ The answer says $\ce{-CH=CH2}$ has higher ...
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What is the correct number of stereo isomers in case of 3,6-dimethylpiperazine-2,5-dione?

What is the correct number of stereo isomers in case of the following compound, i.e. 3,6-dimethylpiperazine-2,5-dione? The answer key gives three, but I think there should be four. I recognised the ...