Questions tagged [stereochemistry]

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

Filter by
Sorted by
Tagged with
1
vote
1answer
37 views

Do we need to check for all kinds of symmetry in a compound to declare it achiral?

I know that a compound is achiral if it contains any one of the following kind of symmetry. 1.Plane of symmetry 2.Centre of symmetry 3.Normal axis of symmetry 4.Alternate axis of symmetry It is ...
5
votes
0answers
46 views

Type of chirality in polycyclic compounds

Ignoring whether or not this molecule could exist, is there a name for this type of chirality? This molecule's mirror image cannot be superimposed on itself but there are no chiral centres. Even ...
-2
votes
0answers
37 views

Is there a planar molecule that is optically active? [duplicate]

Can a planar molecule be optically active? As per my knowledge, any molecule which has a plane of symmetry cannot be optically active and planar molecules have a molecular plane of symmetry. So, can I ...
1
vote
3answers
156 views

What do (2S,3S) and similar notations mean?

When my textbook is discussing stereoisomers with more than one chiral centers, it's using notation like (2S,3S) being an enantiomer with (2R,3R) and so forth. I understand R and S configuration, and ...
-1
votes
1answer
76 views

What does simplest optically active alkene mean? [closed]

I am confused between whether we will call 2,3-dimethyl-cyclopropene or 3-methylpent-1-ene as simplest optically active alkene. Does “simplest” mean aliphatic, or does it mean having least number of ...
-4
votes
1answer
73 views

Terminologies used in isomerism [closed]

What is the difference between the terms constitutional isomers, stereoisomers, geometric isomers? I know cis and trans-1,2-dichloroethane shows cis trans isomerism and 1,1 dichloroethene, 1,1,2 ...
1
vote
1answer
202 views

Stereo-isomerism in 7-methylbicyclo[2.2.1]hept-2-ene

The above are two compounds. The objective is to find if the compounds are identical/enantiomers/diastereomers I can see a plane of symmetry if we keep the $\ce{H-C-CH3}$ in the plane. So, ...
0
votes
0answers
75 views

Number of chiral centers in penicillin V

I have often seen that in many drugs chirality plays a role. So I was trying to analyze the structure of Penicillin V. What is number of chiral centers in the structure of penicillin V? Is the ...
0
votes
1answer
50 views

Which chiral carbon do L and D in L- or D-glucose refer to? [duplicate]

I see and D- and L- glucose are mirror images of each other. and I understand D and L are for chirality. But it is not clear which carbon do D and L refer to. Could anybody let me know? Thanks. What ...
-2
votes
1answer
69 views

Nucleophilic allylic substitution via SN2 [closed]

Since SN2 reaction is more favorable with primary substrates, do allylic primary halides undergo nucleophilic substitution reaction mostly on carbon 1 via "SN2". and in case of secondary ...
1
vote
0answers
53 views

Pseudo chiral centre

I was reading about stereoisomers and I came across a term pseudo chiral centre. I looked up on the net for its definition and found a weird formula for calculating no. of isomers if the compound has ...
6
votes
3answers
252 views

Diastereomers or not

Why is the first one not a pair of diastereomers while the second is? The only reason I could think of was in the first $\ce{Me}$ is the same as $\ce{CH3}$ that is same groups even though differently ...
-1
votes
1answer
44 views

How to obtain optically pure mixture from racemic mixture [closed]

I recently studied stereo chemistry in school.All i know is that compound are optically active if they have no plane of symmetry and about the nomenclature we follow nomenclature....... My questions ...
5
votes
1answer
162 views

In the absence of a physical model, how can I use free software to visualize stereochemistry?

In a different question, the task was to turn a wedge-and-dash representation into a Fischer projection. This involved rotation of a fairly complex molecule - either as a physical model or a mental ...
0
votes
0answers
36 views

Is nitrogen with 3 different substituents and lone pair a chiral center? Does it make the whole compound chiral too? [duplicate]

Is nitrogen considered a chiral centre or stereocenter when it has three different substituents attached to it along with a lone pair. By definition LG Wade says An asymmetric carbon atom is the ...
4
votes
1answer
152 views

Mechanism of three-membered lactone hydrolysis in base

I was reading up on the participation of neighboring functional groups and in the reaction below, I was wondering why hydroxide attacks the C–O bond instead of the carbonyl group of the lactone. ...
2
votes
0answers
34 views

Solvent shell collapse

In "advanced organic chemistry part A" book page:306&307 , the author uses the term 'solvent shell collapse' when talking about the reason for retention of conformation in tertiary ...
1
vote
1answer
68 views

ᴅ-amphetamine, ʟ-amphetamine

The following structural formula (source: Wikimedia) is labelled ᴅ-amphetamine: A Fischer projection of this molecule would contain, I think, the following line: $$\ce{H2N-C-H},$$ and I would have ...
10
votes
1answer
365 views

R/S configuration of bridging carbon in bicyclic system

I am trying to figure out the R and S configuration of bridging carbons in bicyclic systems. In the image, there are two bicyclic systems and depending on the position of the Br substituent, the R or ...
1
vote
1answer
141 views

sp2 hybridisation of alkyl radicals causing formation of racemic mixture

What I know about $\ce{^{.}CR3}$ radical is that it has both $\ce{sp^2}$ and $\ce{sp^3}$ character but the $\ce{sp^2}$ character dominates and so the radical is $\ce{sp^2}$ in nature. So, suppose we ...
10
votes
1answer
424 views

How is plane polarized light rotated by chiral compounds? [duplicate]

There are plenty of questions related to this topic on this site but no proper answer. Can anyone please explain to me how plane polarized light is rotated by chiral compounds, and why it cannot be ...
0
votes
0answers
50 views

Which has a higher enol content between 4-Pyridone and Cyclohexa-2,5-dien-1-one?

I am new to organic chemistry but here is what I feel. 4-Pyridone will have a lower enol content as in its keto form it has higher resonance stabilisation due to the involvement of lone pairs on ...
3
votes
2answers
207 views

Conversion of molecular structure into Fischer projection for compounds having more than two chiral carbons

Question What is the Fischer projection of the given compound's enantiomer? Answer My attempt I tried to solve this by first converting it into the Fischer projection of the given compound and then ...
1
vote
1answer
66 views

Assigning R/S configurations to Fischer projections of 3‐chloro‐2‐hydroxybutanoic acid

A question requires you to assign the R/S configuration for 3‐chloro‐2‐hydroxybutanoic acid: In the answer, while assigning the configuration to carbon #1, apparently the group below is given the ...
1
vote
2answers
117 views

Is chirality absolute or relative?

While going through some questions on chirality and optical isomerism, I came across this compound: Note that I have marked 3 carbons as $C_1,C_2,C_3$ Its obvious that $C_1,C_3$ are chiral carbons. $...
4
votes
1answer
252 views

C₂ axis of symmetry in 1,3-dichloroallene

Is there an $C_2$ axis of symmetry in $\ce{Cl-CH=C=CH-Cl}$? A $C_2$ axis of symmetry means that I should be able to rotate the molecule about an axis by $180^\circ$. But I would need a composition ...
2
votes
2answers
153 views

Why is biphenyl not planar? [closed]

I've seen in a lot of books that biphenyl is not planar. I don't know why that is because both the carbon are $\mathrm{sp^2}$ hybridized so it should be planar. Can someone explain it to me?
3
votes
1answer
118 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
686 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
82 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 ...
0
votes
0answers
50 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
60 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
42 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
100 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
106 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 start. I ...
3
votes
1answer
94 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
197 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
46 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
148 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
121 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
56 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
101 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
42 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
70 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
42 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
128 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
26 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: ...

1
2 3 4 5
13