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
0answers
21 views

Hydroboration, steroselectivity and anti-markovnikov product [duplicate]

My first question has to do with the fact that Hydroboration produces an anti-markovnikov product, why?. I don't see how that happens. A wikipedia artical says that B has a partial positive charge ...
0
votes
0answers
39 views

Does 3‐ethyl‐1,1‐dimethylcyclohexane have a stereocenter?

I knew that we have a stereocenter if the carbon is bonded to four different groups. According to the stereocenter rules, I should have $\ce{CH2}$ bonded to the carbon of the stereocenter (marked with ...
-1
votes
0answers
25 views

Is (Z)-1-bromo-2-chloro-2-fluoro-1-iodoethene optically active or optically inactive? [closed]

Is (Z)-1-bromo-2-chloro-2-fluoro-1-iodoethene optically active or optically inactive? Need a solution of the given problem. My test says it is an optically inactive compound but there seems to be no ...
-2
votes
1answer
33 views

Why these compounds don't show and show Geometrical isomerism? [closed]

I was recently studying organic chemistry related to Isomerism. I have doubt based on an example that is, Why Cumulenes show GI? Why 1-chloro cyclohexene don't show GI?
-2
votes
0answers
17 views

Number of geometrical isomers that are possible in the following compound? [closed]

The number geometrical isomers are present in the given compound is ?
3
votes
2answers
97 views

Is it correct to look at plane of symmetry in substituted cyclohexane for determining a meso compound?

I read this question and it's answer by @orthocresol. Now, he has written that the compound in question is meso not because there is a plane of symmetry but because of the rapid flipping of the ...
5
votes
0answers
89 views

Can cis-trans isomers interconvert?

Can cis-trans isomers interconvert via tunneling ?
1
vote
2answers
53 views

How many structural isomers does 1,2-dimethyl-cyclohexane have?

Can someone tell me how many structural isomers exist for 1,2-dimethyl cyclohexane? My teacher said there is one structural isomer but I believe there aren't any because there is no other way to ...
-1
votes
1answer
49 views

Why is ephedrine optically active? [closed]

Acyclic amine in which three groups are different with a lone pair of electron is optically inactive and nitrogen is achiral because of the rapid pyramidal inversion. Does similar inversion happen in ...
4
votes
0answers
24 views

Does the mechanism of AChE inhibition by Isoparathion depend on chirality?

It is known that the inhibition of acetylcholinesterase by isomalathion can proceed either with diethyl succinate as the leaving group or thiomethyl, depending on the specific stereoisomer of ...
13
votes
1answer
387 views

What are the criteria for a molecule to be chiral?

What are the criteria for a molecule to be chiral? (We frequently get questions of this type, so this is an attempt to construct a suitable general answer for duping.)
1
vote
0answers
31 views

Squiggly line in chemical bond notation [duplicate]

In general is there a convention as to how one interprets squiggly lines in chemical structure notation? e.g. see the below sketch. I suppose it has something to do with cis / trans isomerism. But e.g....
0
votes
0answers
83 views

The nitrile isomers of C5H9N

I got the following 3 isomers of C5H9N correct: I also got the following fourth isomer (ignore the blue dot, it was a slip of the pen!) However, the given answers has the following 2 other isomers ...
4
votes
2answers
108 views

Chirality and Optical activity

Do all chiral objects rotate the plane of polarization of EM waves? For example my hand is chiral, will it rotate the plane of polarization of EM waves of suitable wavelength?
1
vote
1answer
35 views

Stereochemistry + isomer check

We start with compound M: [Please imagine green bonds as dotted bonds going into the plane] From compound M, we are told that the 3 membered ring is opened u using sodium azide yielding a mix of ...
1
vote
3answers
70 views

A question about rotational symmetry of organic molecules and in particular, the cyclic Isomers of C3H4X2

I was thinking about an organic chemistry problem a few days ago but reached a dead end. There were 2 parts to this question. The first was thinking about the isomers of 'C3H4X2' [where X could be ...
1
vote
2answers
38 views

Diastereotopic methylene protons in achiral molecules

Are the protons in methylene groups of achiral molecules such as propane-1,2,3-triol or 3-hydroxypentanedioic acid diastereotopic? Consider propane-1,2,3-triol. To me, replacing one of the protons in ...
6
votes
1answer
153 views

Is (1R,3aR,4S,6aS)‐1,4‐dibromo‐octahydropentalene chiral or achiral?

Is this molecule on the left chiral or achiral? I believe it is achiral because its mirror image (on the right) is essentially the same molecule. But I was told that it is chiral because it doesn't ...
0
votes
1answer
303 views

Which are the Geometrical isomers of the complex [Cr(NH3)2Cl2(en)]+?Is it one or two?

I was recently studying coordination compounds and i came across optical isomerism shown by complexes.I think that the complex i gave above have 4 geometrical isomers(I think this is where I am wrong, ...
0
votes
0answers
23 views

Is writing D-(+)-glucose more correct than D-glucose? [duplicate]

In one of my books glucose is written as D-(+)-glucose everywhere. D represents the position of -OH group with respect to glyceraldehyde.. So D = (+)-Glyceraldehyde.. So won't writing D-(+)-Glucose ...
0
votes
1answer
60 views

stereochem of epoxide opening

Here I have an epoxide opening reaction, but I was wondering that when a nucleophile attacks, How would the stereochemistry work? I have 2 products I predicted and I'm not sure which one would be ...
0
votes
0answers
85 views

Number of stereoisomers of pentane‐2,3,4‐triol [duplicate]

What will be the number of stereoisomers of $\ce{CH3CH(OH)CH(OH)CH(OH)CH3}?$ By formula $2^n - 1 + 2^n + 1/2$ for $n$ being the odd number of chiral centres, it's $6;$ four optically active and two ...
0
votes
0answers
45 views

For a flat, planar molecule, how do you determine which side is up? Or down?

I was just reading about alpha and beta linkages in certain cyclic molecules, and it said that the alpha configuration was the one in which a hydrogen was sticking out above the plane, and an OH ...
3
votes
1answer
70 views

Chiral centres with stereoisomeric substituents

The structure of one particular isomer of 4-chlorohepta-2,5-diene is shown here. I am confused about how two of the propenyl groups attached to the central carbon have the same atoms with different ...
0
votes
0answers
28 views

In which of the these structures C-3 carbon is not a chiral centre?

In which of the these structures C-3 carbon is not a chiral centre? I think that the answer to the above question should be both (b) and (c) as C-3 is attached to same groups and also they have a ...
0
votes
0answers
29 views

Are these molecular structures enantiomers or diastereomers?

What relationship exists between the two structures shown? I think that since the configuration at the bridge head carbons remains the same and only there is an inversion at the carbon bearing $\ce{...
1
vote
0answers
45 views

What do γ (gamma) and λ (lambda) mean in organic chemistry?

From the Wikipedia entry on Cyhalothrin: Pyrethroids such as cyhalothrin are often preferred as an active ingredient in agricultural insecticides because they are more cost-effective and longer acting ...
1
vote
1answer
62 views

Identifying a meso compound

I am still a first year student; I was asked in the exam to identify the meso comound out of some choices. The answer key said that the compound below is meso. But I see no plane of symmetry here. Am ...
-3
votes
1answer
328 views

Why does [Ni(gly)2] show optical isomerism despite having no chiral carbon?

For optical isomerism chiral carbon should be present i.e. carbon with four different groups but this compound doesn't have one then why does it show optical isomerism?
1
vote
1answer
111 views

Understand Hexabromocyclododecane CAS numbers

Hexabromocyclododecane has 16 possible stereo-isomers. So far so good. I found that: 134237-50-6 is the CAS of alpha-Hexabromocyclododecan 134237-51-7 is the CAS of beta-Hexabromocyclododecan ...
1
vote
0answers
68 views

How many monochloro products including stereoisomers of the given compound are possible?

I tried solving problems and I got 2 products. However according to my book the answer is 3 products.
1
vote
1answer
141 views

How many dichlorinated products including stereoisomers can be isolated when (S)-2-chlorobutane reacts with Cl2 /hv?

This is my attempt at solving this problem. I get 6 products. However my book says the answer is 5 products.
0
votes
1answer
36 views

Stability of Gauche and Anti form in conformational Isomerism

I came through this question: Which form is stable Gauche or Anti in F-CH2-CH2-F? My answer: Due to lone pair repulsion Anti form should be more stable but the answer is given Gauche form. Please tell ...
1
vote
1answer
68 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
62 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 ...
1
vote
3answers
2k 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
842 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
83 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
252 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, ...
2
votes
1answer
415 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
68 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
90 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
1answer
845 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
266 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
52 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
172 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
37 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
198 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
35 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
121 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 ...

1
2 3 4 5
14