Questions tagged [stereochemistry]
Applicable to questions about the spatial arrangement of atoms in a molecule and how they affect its physical or chemical properties.
620
questions
1
vote
1answer
48 views
Number of Stereoisomers of C(CHClCH3)4
I am having trouble understanding why the structure
$$\ce{C(CHClMe)4}$$
has only five stereo isomers. According to my textbook, the stereo isomers correspond to the following series of absolute ...
14
votes
3answers
555 views
Can geometrical isomers be enantiomers?
I have just been pondering upon the question above. I have found this example and I am sure they are enantiomers, but do they also count as geometrical isomers?
-2
votes
1answer
80 views
I need help with Cahn-Ingold-Prelog (boat conformation)
I need to decide if the chiral carbon (with the attached hydrogen) is in R-configuration or S-configuration. To be able to do that, I need to know which of the atoms are pointing backward, forward and ...
-1
votes
0answers
18 views
how do you know if a Newman projection is chiral? [closed]
how do you know if a Newman projection is chiral?
while converting it newman projection into sawhorse how do we know if the compound is chiral or Achiral
0
votes
0answers
46 views
E-Z system without a double bond
Can we apply E-Z nomenclature to geometrical isomers without a double bond. For example, can we use it for cis and trans isomers of 1,2-dimethylcyclohexane?
-1
votes
1answer
28 views
Are the C1 and C3 carbons of cis 1-bromo-3-chloro-cyclobutane chiral?
I have tried to approach this from 2 directions:
The ‘official’ method my textbook gives, which gives the correct answer - They are achiral
It consists of going ‘priority-wise’ from the two carbons ...
3
votes
1answer
23 views
Total number of isomers formed on monobromination of 2-methylbutane
What is the total number of isomers formed on monobromination of 2-methylbutane (including configurational and stereoisomers)?
I tried working it out. However, I found only five:
According to the ...
0
votes
1answer
40 views
Optical activity of 3‐chlorobutan‐2‐ol
In the picture that I have uploaded, I have read that the given compound is chiral.
But on drawing the sawhorse structures (for better visualisation), I feel like the compound is symmetric about a ...
3
votes
1answer
50 views
Total number of stereoisomers of truxillic acid
Total number of stereoisomers of the compound will be:
This was a question asked in our mock test. I've tried by considering pseudo-chirality on the carbon atoms. But I don't know where to ...
3
votes
1answer
80 views
Which ethanol derivatives display the gauche effect?
How many of the following ethanol derivatives of the form $\ce{GCH2CH2OH}$ have a more stable gauche conformer compared to their anti conformer?
$G = \ce{F}, \ce{Cl}, \ce{OH}, \ce{NH2}, \ce{OMe},...
2
votes
1answer
127 views
What is the difference in dehydration of cis- and trans-1,2-cyclohexanedicarboxylic acid in anhydride formation?
Is there some required stereochemistry for anhydride formation? Do both of them form the same product, or does one not even undergo dehydration?
I looked up cyclohexane-1,2-dicarboxylic anhydride's ...
2
votes
0answers
37 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 ...
3
votes
0answers
20 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 ...
-1
votes
1answer
31 views
MA3B3 isomers - is this same as meridional one? [closed]
I'm new to studying stereo chemistry. (Now I'm studying coordination complexes.)
In my class material and other some datas(from google), it says that there is two, fac and mer.
I want to know is ...
1
vote
2answers
51 views
How to check which compound will show optical isomerism?
So my teacher told that those compounds which have one or more chiral carbon present in them it will definitely show optical isomerism because it has an optically active stereoisomer, but there are ...
6
votes
0answers
54 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 ...
1
vote
0answers
65 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 ...
0
votes
0answers
40 views
Converting Fischer formulas to Newman projections
How are line diagrams of molecules converted to their Newman projections? All I got from looking it up is that one may convert a Fischer formula to an eclipsed conformation directly, and that this may ...
-1
votes
2answers
62 views
Find the number of geometrical and optical isomers of 1,2,3,6-tetramethyl cyclohex-1,4-diene
The compound given to me is 1,2,3,6-tetramethyl cyclohex-1,4-diene.
The geometrical isomers for the following compounds are:
The isomer on the right can also be an optical isomer with its enantiomer....
12
votes
4answers
1k views
How is exact racemization possible? [closed]
A racemate consists of 50 % $d$ and 50 % $l$ forms of an optically active compound. But how can someone ensure exact 50% quantity comparing molecule by molecule? There will always be some difference ...
-2
votes
1answer
37 views
R-S configuration or Cahn-Ingold-Prelog configuration [closed]
How to assign R and S configurations in alkenes and more complicated structures ?
I know that the groups attached to the sp3 hybridized carbon is first prioritized by atomic number then we see the ...
3
votes
2answers
97 views
Number of optically active isomers of [Co(NH3)2Cl2(NO)(OH)]?
My Attempt:
Since Compound is of the form M[a2b2cd]
I got three optically active isomers of the form M[(ab)(ab)(cd)] , M[(ab)(ac)(bd)] , M[(ab)(bc)(ad)]
and since NO is a bidentate ligand, total ...
-4
votes
1answer
24 views
If a molecule with 3 chiral centers that are all R, is it the same as the S version? [closed]
Consider a molecule with 3 chiral centers all marked R. Is this molecule the same as the S version?
1
vote
0answers
43 views
Does orientation matters to this extent in reactions?
In the above question I know that the three reactions involved are $\mathrm{S_N2}$ reactions and therefore there shall thrice inversion of the substitute.
So, I got the solution for the MCQ as:
...
5
votes
1answer
181 views
Why is 3,6-dimethylpiperazine-2,5-dione optically active in spite of having a centre of symmetry?
I learnt in my chemistry class that if a molecule has an element of symmetry (either a plane of symmetry or a centre of symmetry), it will not be chiral and hence will not show optical activity.
My ...
0
votes
0answers
35 views
Are centre of symmetry(COS) and alternate axis of symmetry(AAOS) dependent on each other?
COS=Centre of symmetery
AAOS=Alternate axis of symmetry
Lets suppose a molecule has a COS. Does it need to have AAOS?
What about the converse? If a molecule has AAOS does it necessarily have a COS?
...
0
votes
1answer
91 views
A question about geometry of benzenetetrol
In the 3d conformation of 1,2,4,5 - benzenetetrol, how could i determine the direction to which hydrogen atoms of hydroxyl groups would point? and if there were tertiary butyl groups in positions 3 &...
2
votes
0answers
68 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 ...
0
votes
1answer
72 views
Will the following complex show optical isomerism
So there is this question which asks whether the following complex
$\ce{[Co(NH3)4Br2]+}$
will show optical isomerism or not.
According to my knowledge it will show optical isomerism in cis ...
1
vote
1answer
472 views
Number of possible isomers (including optical/geometric ones) with C4H8O molecular formula [closed]
I found 32 isomers but I think I made a miscount.
Chain alcohols: 6, chain ethers: 5, and chain carbonyl compounds
(ketones/aldehydes): 3
Three-member ring alcohols: 7, three-member ethers: 6 (...
2
votes
0answers
78 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 -
(...
1
vote
0answers
40 views
What is the priority order of the four groups?
I'm trying to figure out whether this is in R/S configuration....I thought it would be R since the groups seem to be decreasing in priority in the clockwise direction (since F has the largest atomic ...
-3
votes
1answer
44 views
Comparing different stereochemistry terms [closed]
What is the difference between:
Meso compound and an optically inactive compound
Chiral compound and an optically active compound
For all examples i have seen, chiral compounds were optically active ...
0
votes
0answers
29 views
Why doesn't anomeric effect predominate over steric effects in glucopyranose?
$\beta$-D-(+)-glucopyranose is more stable than $\alpha$-D-(+)-glucopyranose. Why is this?
I know that in $\beta$-D-glucopyranose all the hydroxyl groups are in the equatorial position and thus it ...
0
votes
2answers
177 views
Why are there two structures of L-Glucose in the Fischer projection?
We are told that L-Glucose is an enantiomer of D-Glucose, which would mean that they are mirror images of each other. But then we're also told that the L and D forms is determined by the spacial ...
2
votes
0answers
23 views
Carbon dioxide electronic geometry [duplicate]
It is known that allene (propadiene) $\ce{H2C=C=CH2}$ geometry is such that its hydrogen atoms are not in the same plane – do not form rectangle, but “extended tetrahedron”
I wonder if structurally ...
1
vote
1answer
51 views
Confusion with E/Z configuration
Could someone please illustrate how to determine the E/Z configuration of this molecule?
What I understand so far is that if the two highest priority substituent on each side are on the same side, ...
-1
votes
1answer
45 views
Optical activity of cis-trans isomers of a co-ordination compound [closed]
Why do geometrical (cis and trans) isomers of [Pt(NH3)(Br)(Cl)(py)] not show optical activity ? Thanks In Advance...
2
votes
1answer
79 views
Why glucose and other similar carbohydrates are oxidised fully by HIO4?
$\ce{HIO4_{(aq)}}$ requires the vicinal diols to have syn configuration, as it forms a cyclic periodate ester.
But glucose does not have syn configuration at C3, and if you consider cyclic forms of ...
8
votes
2answers
1k views
Are monosubstituted cyclopropanes achiral or chiral?
A classmate an I were discussing the chirality of this molecule which is a monosubsituted cyclopropane. I argue this is an achiral molecule because that carbon which is bonded to bromine cannot be a ...
0
votes
1answer
82 views
Which of the following isomers of 2,3‐dihydroxy‐4‐methoxy‐4‐oxobutanoic acid are identical?
Which of the following are identical?
A and B are identical
A and B are diastereomers
A and C are enantiomers
A and B are enantiomers
What I know is that when we rotate a ...
7
votes
3answers
1k views
Which biphenyl is optically active?
Which biphenyl is optically active?
I know that it can never be 1. I don't think it will be 4 either as I read that it should be ortho-substituted biphenyl.
So, when I look at 2 and 3, I can't ...
1
vote
0answers
35 views
What is the absolute configuration of carbon 5 in 5-bromo-2-methylhex-2-ene
I am trying to work out the absolute configuration around carbon atom 5 in 5-bromo-2-methylhex-2-ene. Could someone please let me know if my working is correct? Does the wedged bond from C4 to C5 ...
3
votes
0answers
75 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 ...
1
vote
1answer
136 views
Conformers of a meso-compound [duplicate]
In a particular question in one of my reference book, I was asked if the given compound (meso-butane-2,3-diol) was a meso compound or not. In it’s solution part, to show that the compound was ...
1
vote
1answer
214 views
Optical activity of cis coordination compounds
I came across a statement saying,
"Consider a Octahedral coordination compound of type [MA2X2]. Then,
if the compound is in a cis form, it shows optical activity as there
is no plane of ...
1
vote
1answer
257 views
Number of Stereoisomers for Terpin
Terpin (4-(2-hydroxypropan-2-yl)-1-methylcyclohexan-1-ol) has two $\mathrm{sp^3}$ carbons with different substituents on a cycloalkane, so it has two cis-/trans-isomers, and from what I was taught, is ...
2
votes
0answers
56 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]...
1
vote
0answers
46 views
Cis/trans with alkene substituents on cycloalkanes
My chemistry book is saying that the double bond indicated by the red arrow can generate cis/trans isomers:
I don't understand how this can be so, as you need to use E/Z priority rules in this case. ...
2
votes
1answer
542 views
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
...
