Applicable to questions about the spatial arrangement of atoms in a molecule and how they affect its physical or chemical properties.
1
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1answer
25 views
Classification in Stereoisomerism
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 ...
5
votes
0answers
58 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 ...
6
votes
1answer
348 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 ...
2
votes
1answer
40 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 ...
-1
votes
1answer
30 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 ...
0
votes
0answers
18 views
How to calculate total number of stereoisomers for symmetrical molecules/compounds? [closed]
Is there any formula in terms of n(stereogenic center).
Like there is formula for unsymmetrical compounds, total stereoisomers= 2^n
I searched about this on web but no one is talking about ...
-1
votes
1answer
56 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 ...
0
votes
2answers
42 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 ...
0
votes
0answers
20 views
Can the CDK represent a mixture of stereoisomers
Biovia (previously MDL) Enhanced Stereochemical Representation enabled specifying mixtures of enantomiers by annotating sterocenters with a group and one of these types:
ABSOLUTE:
Stereogenic ...
1
vote
0answers
20 views
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 ...
-1
votes
1answer
28 views
what is superimposability of mirror images of this molecule? [closed]
I don't get why (a) and (d) are achiral when we cant superimpose their respective mirror images?Or can we superimpose them?
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2answers
94 views
Fischer projections
Can somebody tell me how why they changed/choose the groups for vertical and horizontal lines. As far as I know the vertical lines represent group going away from us and horizontal depicts coming ...
0
votes
0answers
56 views
Interpreting wedge dash
What does wedge-dash in this structure diagram of 2'-methoxy-6-nitro[1,1'-biphenyl]-2-carboxylic acid mean? Both the structures are perpendicular to each other, so why is wedge dash shown on front ...
0
votes
0answers
35 views
R/S descriptors in long carbon chain
I'm trying to figure out how to assign R/S descriptors using a Fischer model without transforming it into a spacial one.
What I learned so far is the method to assign it for 'terminal' (I'm gonna use ...
2
votes
2answers
91 views
Stability of geometrical isomers in cycloalkanes
Among the following, which should be the most stable compound?
1)Cis-cyclohexane-1,2-diol
2)Trans-cyclohexane-1,2-diol
3)Cis-cyclohexane-1,3-diol
4)Trans-cyclohexane-1,3-diol
My thought process is-...
1
vote
0answers
33 views
Which of the following molecules are enantiomers? [closed]
My book says that only molecule 7 is enantiomer of molecule 1. Why is this? Why can't molecule 1 and 2 be enantiomers?
1
vote
1answer
37 views
Are Anomers Epimers?
epimers are the class of stereoisomers which differ along configuration at any carbon in a carbohydrate(generally),
And anomers are the kind of stereo isomers that differ at the carbonylic carbon, ...
2
votes
1answer
123 views
2
votes
2answers
94 views
Can chiral atoms have same substituents but with different orientations?
So consider this molecule. We have to determine whether nitrogen atom is chiral or not.
MY IDEAS:
Now going by all I have read, for chiral atoms only criteria is substituents to be different. Here ...
9
votes
5answers
914 views
If a chiral molecule reacts with an achiral molecule will the product be chiral or achiral?
My book says that a pair of enantiomers will react the same way with an achiral substance.
How is this possible? Does this imply that the product is achiral, even though the enantiomers are chiral? ...
7
votes
2answers
135 views
Number of spatial arrangements of tetrasubstituted biphenyl
According to my book 2-bromo-2'-(1-chloroethyl)-6'-iodo-6-(prop-1-en-1-yl)-1,1'-biphenyl has eight possible spatial arrangements. How can this be so? I can think of only four – left two groups being ...
2
votes
1answer
67 views
Cahn–Ingold–Prelog priority of CN vs CH2NH2
Why does $\ce{CH2NH2}$ have lower priority than $\ce{CN}$? The carbon on the first molecule is bonded to (N,H,H) while the carbon on the second molecule is just bonded to (N). I can't seem to find ...
0
votes
0answers
36 views
What compounds give two products on reacting with NH2OH?
This is a question from the chapter stereochemistry of my coaching module. The answer options include CH3CHO, DCHO, etc. How do I do this? I have an idea that if we take a racemic mixture of D and L ...
6
votes
2answers
465 views
Do you assume undrawn hydrogens are pointing away from you when determining R/S?
When determining R/S of stereoisomers, the group with the smallest atomic number needs to be in the back (dashed line). But if no group attached to a chiral center is drawn in dashed line, do we ...
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votes
1answer
59 views
Twisting stereoisomers with rings to determine R/S [closed]
I know that if the smallest atomic number group is not in the back, we can twist the molecule so that it is in the back and then determine if it is R/S (Left image). But if the chiral center is ...
-1
votes
1answer
47 views
Stereogenic Center Question
In cholesterol, I don't understand why the two points I circled are stereogenic centers. Isn't the left carbon attached to an OH, H, CH2, and CH2? And isn't the right carbon attached to CH, CH2, CH, ...
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votes
1answer
207 views
Explain optical activity in Biphenyl compounds
How is optical activity explained in biphenyl compounds using atropisomerism.
NOTE: I was taught that if vertical symmetry exists then optical activity is not shown by any substituted biphenyl ...
1
vote
1answer
184 views
H-NMR Equivalent Protons and Coupling of Glycerol
I've been searching for explanations to understand why the labeled protons on carbons 1 and 3 are not equivalent in the below figure.
Another figure that shows the same results:
SDBS confirms the ...
0
votes
1answer
77 views
Systematic Approach to Finding Number of Isomers [duplicate]
I have this compound
I want to know how many isomers (including stereoisomers) may have this constitution. Is there a systematic approach towards solving such types of problems related to the total ...
0
votes
0answers
53 views
How many stereoisomers can exist for 4,5-bis(3-hydroxyoct-1-en-1-yl)cyclopentane-1,3-diol?
This is from this year's JEE Advanced question paper.
I thought the answer to be atleast 32 because of exactly 5 stereocentres present. One of the double bond cannot show geometrical isomerism ...
0
votes
2answers
80 views
Meso and achiral does both term means the same?
When a molecule has plane of symmetry, or centre of symmetry it is termed as an achiral compound (though it contain some chiral centres). Same goes for the meso compounds due to the internal ...
2
votes
0answers
62 views
Dextro or laevo-rotatory compound conversion [closed]
Will applying an external electric field to a racemic mixture will convert the optically active compound(mixture of both Dextro and laevo-rotatory) into a particular dextro or laevo-rotatory compound?
...
3
votes
1answer
52 views
Under what circumstances can the stereochemistry at nitrogen atom be faithfully retained and identified?
Under what circumstances can the stereochemistry at nitrogen atom be faithfully retained and identified?
Because in most cases nitrogen atoms tend to undergo stereorandomisation by flipping due to ...
0
votes
1answer
102 views
1,4-diphenyl-1,3-butadiene (E,E) and (E,Z) Isomer Newman Projections
I was wondering if it is possible to draw the Newman projections of the (E,E) and (E,Z) isomers of 1,4-diphenyl-1,3-butadiene in the following manner that I have? I wasn't quite sure about how to ...
3
votes
1answer
258 views
How to calculate the percentage yield for enantiomers in free radical halogenation?
How many mono-chlorinated products of 2-methyl butane will be formed upon chlorination in the presence of sunlight?
Find the percentage of major product formed.
Six products were formed: two ...
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votes
1answer
85 views
Number of total stereoisomers of a piperazine derivative
How do I find out the total number of stereoisomers of 3,6-dimethylpiperazine-2,5-dione?
As far as I can see, the compound has two chiral carbons. Would the nitrogens make a difference? They seem ...
2
votes
0answers
73 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 ...
13
votes
2answers
590 views
Number of stereoisomers of tetramethylspirononane
The above compound – 2,3,7,8-tetramethylspiro[4.4]nonane – clearly exhibits both optical and geometrical isomerism. The question is, how many stereoisomers does it have in all?
As the number of ...
2
votes
0answers
91 views
How to find the number of optically active and optically inactive isomers for a spiropentane derivative? [duplicate]
What will be the number of optically active and inactive isomers 1,2,4,5-tetramethylspiro[2.2]pentane?
The question asked for the difference between number of optically active and optically inactive ...
0
votes
1answer
62 views
Could thin layer chromatography separate enantiomers? [duplicate]
My textbook states the thin layer chromatography could separate enantiomers only if both/or the mobile and solid phases are chiral?
Why so?
0
votes
1answer
186 views
What is the difference between chiral molecule and chiral carbon? [duplicate]
I read in my book, that substituted allenes do not have chiral carbons, but actually the molecule is chiral, so they show optical isomerism. But what is the difference between them( chiral carbon and ...
4
votes
2answers
109 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 ...
3
votes
1answer
40 views
Effect of stereoisomerism and racemization on solubility
I was on the Wikipedia page of Tartaric Acid, and I noticed that its solubility in water varies depending on whether the solution is racemic, meso, or optically active:
$$\begin{array}{|c|c|} \hline
&...
0
votes
1answer
61 views
What is it meant by two different groups in stereoisomerism?
I understand there are some properties in an organic compound that allow stereoisomerism.
double bond can't rotate
two double bonded carbon atoms each have two different atoms or groups attached
I'm ...
4
votes
1answer
56 views
Stereoselectivity of Roush crotylboration
One can use a tartrate derived boronate to enact enantioselective crotyl transfer. Eg in scheme below:
I do not understand how the stereoselectivity arises. We have a chiral boronate, true, and we ...
1
vote
0answers
36 views
Can a molecule be achiral whilst it's resonance form chiral? [duplicate]
I'm trying to work out whether this
It is my understanding that the sulfur is sp2 hybridised. Why is this? The central sulfur atom is bound to 3 atoms and then has a lone pair, so surely it is sp3 ...
2
votes
1answer
40 views
Is there a characterisation for conjugated dienes similar to cis-trans?
As shown above,we know there are two configurations possible for conjugated dienes.
Are they given any special names like we have cis and trans?
This came up because while studying the Diels Alder ...
1
vote
1answer
371 views
Which one of the following is optically active?
To be optically active the presence of chiral centres are very important but if there exists a plane centre or axis of symmetry then the molecules are optically inactive. How to determine the optical ...
0
votes
2answers
150 views
Esterification of racemic acid with optically active alcohol
An excess of racemic acid ($\ce{CH3CHClCOOH}$) is allowed to react with (S)-2-methyl-1-butanol to form the ester, $\ce{CH3CHClCOOCH2CH(CH3)CH2CH3}$, and the reaction mixture is carefully distilled. ...
8
votes
4answers
457 views
Mismatch of plane of symmetry vs Gold Book's definition for a pseudochiral carbon
Here is pentane-2,3,4-triol:
At first glance, without deciding the configurations at each chiral carbon, we can clearly see that this molecule has a plane of symmetry, perpendicular to the plane of ...
