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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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Calculation of no. Of stereoisomers [on hold]

I am confused as how to do the ques , should i take the ring as a single stereocentre or should i consider the no. Of single bonds about which the groups are showing GI in the ring.(https://i.stack....
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1answer
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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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Mass percentage prblem from chang chemestry book [on hold]

I need help with a exercise from Raymond Chag chemistry book (11th edition): If for each $\ce{N}$ atom from $\ce{C3H5N3O9}$ (Nitroglycerin) forms one $\ce{NO}$ (nitric oxid) what is the percentage ...
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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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0answers
29 views

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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1answer
38 views

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 ...
2
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1answer
35 views

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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1answer
30 views

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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2answers
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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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0answers
22 views

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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Stereochemistry in Grignard reaction

How do I make all stereochemical products possible for the following reaction? My book cover reactions that don't incorporate these fisher representations, please help me learn this.
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1answer
282 views

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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0answers
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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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1answer
187 views

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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3answers
198 views

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
370 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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1answer
34 views

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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2answers
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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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1answer
77 views

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 ...
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1answer
70 views

Predict stereochemistry of product [closed]

When 3-methyl(1,1-2H2)pent-1-ene reacts with HCl, why do we obtain a racemic mixture? The given reactant is optically pure.
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1answer
154 views

Are all alkene geometrical isomers achiral?

I was reading a book and it tells that alkene geometrical isomers are achiral. I wanted to know that is it applicable for alkene geometrical isomers? Thanks in advance.
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1answer
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What do D and L stand for in the Fischer-Rosanoff convention?

In R and S configuration, the R stands for rectus and the S stands for sinister. Similarly, do the D and L descriptors in the Fischer-Rosanoff convention stand for something?
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1answer
189 views

number of optical isomers of a cyclic molecule

What is the number of optical isomers for this compound? Also, there seems to be no clear-cut boundary between geometrical isomers and optical isomers. Referring to a post in StackExchange, is (RS)- ...
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0answers
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Number of products on dehydrobromination

Question: The total number of alkene products possible from the dehydrobromination of 3-bromo-3-cyclopentylhexane using alcohol KOH is : This question was asked here before but I am getting more ...
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1answer
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Depicting molecules by Natta projection

Does anyone know the meaning of these two bonds in stereochemistry? These bonds are provided by the $\mathrm{\LaTeX}$ chemfig package. The creator of the ...
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1answer
75 views

Can anyone tell me what reaction is this?

I came across this reaction, but I have no idea what reaction is this. Can anyone please tell me? What will be the products? My first guess is that a carbene will be formed which will attack on the ...
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1answer
63 views

Total number of stereoisomers of 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane [duplicate]

I don't think there is any change of showing geometrical isomerism across the double bond because the two groups on the right side (two $\ce{-CH_3}$) are the same. Also I don't think there should be ...
3
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1answer
118 views

How many stereoisomers are possible for 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane?

How many stereoisomers (not counting different conformers) does 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane have? I think the answer should be 3. There are two geometrical isomers (cis and ...
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0answers
33 views

Diels Alder stereoselectivity

I'm familiar with the endo rule as well as the regioselectivity of the reaction. However, what I fail to understand is the stereoselectivity of the product in relation to the diene. For example, in ...
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1answer
42 views

Optical activity of organic compunds

Why are the molecules which are superimposable on their mirror images optically inactive? For example 1-bromo-2-methylpropane.
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4answers
115 views

Total number of stereoisomers of 2,3,5,6-tetrachlorooctane

I tried the following combinations: RRRR, SSSS, RRRS, SSSR, RRSS, RSRS, SRRS, RSSR, RSRR, SRSS, RRSR, SSRS, SSRR, SRSR. So total stereoisomers which I got is 12 but my teacher says it's 16. I don't ...
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0answers
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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 ...
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0answers
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Enantioselective alkylation of Aldehydes by Dialkylzinc reagents

Enantioselective catalysis is one of the important reactions in Organic chemistry which has huge applications in practical basis for synthesis of optically pure natural compounds. In this respect, I ...
4
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1answer
98 views

Optical Isomerism in Coordination Compounds of type MA₂B₂(CC)

I was asked the following question: How many optical isomers are there for $\ce{[Cr(NH3)2Cl2(en)]^+}$ ? First of all I figured out the following four geometrical isomers of the above complex: Out ...
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2answers
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Is there absolotely no relation between R/S configurations and d/l optical rotations?

Is there such a relation between R/S configurations and d/l optical rotation that, if we experimentally know that R configuration of a fixed compound gives 'l' rotation then can we infer that the S ...
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1answer
35 views

Enantiomers and couple of enantiomers

I ask myself a question for some time but it's impossible to me to find the answer! I can't understand the difference when we say " that molecule has a enantiomer " and when we say " has a couple of ...
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0answers
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X-ray structure analysis mirrored coordinates?

How to ensure, that X-ray crystallography structure analysis was done right to provide correct, non-mirrored atomic coordinates? Example: Following Wikipedia image, is generated from data taken from ...
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3answers
178 views

Is there a thermodynamic driving force for racemisation?

Why does racemisation occur? My doubts are: Is it due to entropy? If it is due to entropy, how is the reduction of optical activity by racemisation a consequence of increased thermodynamic ...
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1answer
35 views

What is the configuration of dimethyl[tris(trifluoromethyl)]-λ⁵-phosphane?

I know that $\ce{(CH3)2P(CF3)3}$ is geometry of trigonal bipyramid and according to Bent's rule $\ce{CH3}$ goes to axial positions and $\ce{CF3}$s remains on equatorial positions. However, as per ...
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2answers
107 views

Does 3,6-di-X-cyclohexa-1,4-diene have stereo centers?

The following question has multiple correct answers: The book out of which the question is taken shows that a, b and d are correct answers. According to me c should also be correct, as it shows ...
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2answers
55 views

Are the stereoisomers of nucleosides actually anomers?

An anomer is an epimer at an (hemi)-acetal carbon like $\ce{R2C(OR')2}$. Why is the 1'-position of a nucleoside referred to as the anomeric center despite the lack of acetal functional groups?
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1answer
64 views

According to the Cahn-Ingold-Prelog system assign a priority to each of the following groups. (Highest priority is 1) [closed]

1-CH(CH3)CH2F 2-CHCl2 3-CH2Br 4-C(CH3)3 this is the order i did using the system but i am having a hard time understanding it and was wondering if anyone could tell me if my answer is correct, and if ...
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1answer
153 views

Classification in Stereoisomerism [closed]

I was trying to understand stereoisomerism. I am having trouble creating a 'flow chart' of Stereoisomerism. While there are many sources available over the internet and books, I don't find a standard ...
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0answers
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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 ...
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1answer
502 views

Are there chiral compounds that don't rotate plane-polarized light?

I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit ...
3
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1answer
62 views

Assign stereodiscriptor to 4th carbon of 3-ethyl-2,4-dimethly-5-(propan-2-yl)heptane-1,7-diol

Here is the molecule. Clearly the 4th carbon is chiral. I have drawn the diagraph for it, but the exploratory pathways of the left and right chains are the same. So, the problem is that the two chains ...
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2answers
269 views

Why does 1,3-dichloropropane not show stereoisomerism?

It is a multiple choice question: Which compound does not show stereoisomerism? A 1,2-dichloroprop-1-ene B 1,2-dichloropropane C 1,3-dichloroprop-1-ene D 1,3-dichloropropane I ...
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1answer
587 views

Determining R and S configuration for a cyclic compound when the lowest priority group is on the plane of the paper

I am struggling with determining R and S configuration for the following compound I know how to give R and S configuration for a cyclic compound like the compound above if the lowest priority group ...
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2answers
240 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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0answers
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Why atropisomers are called conformers?

Changing one atropisomer to another requires bond breaking (in some cases the removal and reattachement of steric groups, according to my understanding) so how it is possible that according to IUPAC ...