Questions tagged [stereochemistry]

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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6
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3answers
240 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 ...
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1answer
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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 ...
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1answer
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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 ...
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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 ...
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1answer
126 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. ...
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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 ...
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1answer
60 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
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1answer
339 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 ...
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1answer
127 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
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1answer
410 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 ...
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0answers
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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 ...
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2answers
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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 ...
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1answer
55 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 ...
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2answers
114 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. $...
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1answer
207 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 ...
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2answers
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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?
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1answer
113 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 ...
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3answers
635 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?
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1answer
81 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 ...
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0answers
49 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?
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1answer
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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
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1answer
33 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 ...
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1answer
83 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 ...
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1answer
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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 ...
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1answer
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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},...
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1answer
176 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 ...
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0answers
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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 ...
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0answers
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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 ...
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1answer
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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 ...
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2answers
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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 ...
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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 ...
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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 ...
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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 ...
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2answers
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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....
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4answers
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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 ...
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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
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2answers
118 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 ...
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1answer
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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?
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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
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1answer
185 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 ...
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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? ...
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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 &...
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0answers
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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 ...
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1answer
90 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 ...
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1answer
956 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 (...
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0answers
90 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 - (i) 1,4-...
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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 ...
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1answer
45 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 ...
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0answers
34 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 ...
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2answers
266 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 ...

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