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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votes
1answer
28 views
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votes
0answers
28 views
Stereochemistry [on hold]
The answer to this question is option (d). Can anyone please explain the reason?
2
votes
1answer
96 views
-1
votes
0answers
12 views
Clarification regarding pure chiral isomers [closed]
I was doing some stereochemistry and i got a confusion about the exact definition of pure chiral isomers.Isnit possible that pure chiral reagent can only have one stereogenic center?thanks for help ...
2
votes
2answers
76 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 ...
-1
votes
0answers
22 views
9
votes
5answers
835 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? ...
2
votes
1answer
46 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 ...
-1
votes
0answers
25 views
Stereochemistry confusion [duplicate]
While dealing with molecules we try rotate the mirror images and then try to superimpose them. That's ok . But our hand are mirror images and I tried a exercise by keeping both hands like this
Then ...
1
vote
1answer
43 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
33 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
451 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 ...
-1
votes
1answer
43 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
38 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, ...
-1
votes
1answer
81 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
2answers
98 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
72 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
49 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
56 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
54 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
49 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
57 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
139 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 ...
-1
votes
1answer
65 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
58 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 ...
12
votes
2answers
396 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
84 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
44 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
93 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
108 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
35 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
60 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
52 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
35 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
34 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 ...
0
votes
1answer
235 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
130 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
397 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 ...
-1
votes
1answer
98 views
Counting number of stereo isomer
I am having trouble counting the stereo-isomers in this structure:
There are no chiral carbons.
The double bonds means there maybe cis-trans geometrical isomerism but the groups are different. So ...
-3
votes
1answer
312 views
Difference between L&D and S&R in naming [duplicate]
What is the difference between L&D and S&R? Can we say S-alanine instead of L-alanine?
1
vote
1answer
270 views
How are these molecules chiral and achiral?
I always thought that a molecule couldn't be chiral if it had a plane of symmetry. Doesn't the chiral molecule here have symmetry diagonally across the OHs?
The achiral one doesn't look symmetrical ...
8
votes
1answer
355 views
Racemization of ketones in presence of catalytic acid
Question:
Which of the following ketones racemise in aqueous solution containing acidic or basic impurities?
My answer:
A and B should racemise in aqueous solution, for the carbonyl groups in A and B ...
3
votes
1answer
107 views
Understanding the CIP configuration for cyclic substituents with hetero-oxygen atoms
As per CIP sequence rules, the topmost $\ce{C}$ on the left gets 1st priority. Moving on to the right side of the double bond, we have:
Top $\ce{C}$: ($\ce{C}$,$\ce{O}$,$\ce{O}$,$\ce{H}$)
Bottom $\...
13
votes
1answer
230 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 ...
0
votes
1answer
80 views
Reactions of differents halohydrins with tert-butoxide
I have two compounds (1R,2S)-3,3-dimethyl-2-bromocyclohexanol and (1R,2R)-3,3-dimethyl-2-bromocyclohexanol, both of them are treated with $\ce{KO^tBu}$ (a strong but bulky base) to form two ...
8
votes
1answer
388 views
What are the CIP rules for cyclic substituents?
Here's what I read on Wikipedia (section "Cycles"):
To handle a molecule containing one or more cycles, one must first expand it into a tree (called a hierarchical digraph by the authors) by ...
2
votes
1answer
379 views
Why does 1,2-dimethylcyclohexane only possess three stereoisomers? [duplicate]
Why does 1,2-dimethylcyclohexane in chair form have only three stereoisomers?
I understand that the trans isomer doesn't possess plane of symmetry and thus it has two stereoisomers. But my book says ...
3
votes
1answer
289 views
Is trans-1,2-dimethylcyclopropane optically active or not?
According to my book it is optically active, but no valid reason is given. But what I found is there exists an alternating axis of symmetry, and so my conclusion is the compound would be inactive or ...
-1
votes
1answer
147 views
Conditions for Chirality in optical isomerism [duplicate]
Is it necessary that any atoms which is chiral must have 4 different atoms around the central chiral atom(maybe it can be carbon if it's organic molecule) bonded to it?
More specifically:
I mean can't ...
8
votes
1answer
679 views
Can a lone pair be involved in cis/trans isomerism?
I was trying to find whether a molecule showed isomerism, and this is what I came up with.
I thought this was the case as I took the nitrogen to be sp2 hybridised, thus trigonal planar (with the ...
