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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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: ...
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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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Draw all the unique stereoisomers for the following and label all stereoisomeric relationships as either enantiomers or diastereomers [closed]

Draw all unique stereoisomers and label all stereoisomeric relationships as either enantiomers or diastereomers
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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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Stereochemistry. Difficulty seeing no. Of boiling fractions [closed]

Answer given is six . I can't understand it shouldn't it be 4 as they will be optically active
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Stereochemistry. I having difficulty seeing chirality [closed]

Answer given is d. I got diastereomers which I think we're chiral
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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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does nitroethane show tautomerism?

keto enol tautomerism is possible only in those carbonyl compounds in which at least one alpha- hydrogen atom is present so that it may convert the carbonyl group to enol group. In nitro Ethane there ...
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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
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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
121 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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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 - (...
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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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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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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
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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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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 ...
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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, ...
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1answer
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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...
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1answer
60 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 ...
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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 ...
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1answer
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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 ...
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3answers
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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 ...
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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 ...
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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 ...
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1answer
111 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 ...
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1answer
147 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 ...
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1answer
178 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 ...
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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]...
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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. ...
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1answer
406 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 ...
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1answer
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Assigning Cahn-Ingold-Prelog priority numbering rules for 2 groups

I was asked to draw the perspective formula of $$\ce{(3R,4R)CH2=CH-CH(CH3)-CH(CH3)-CH2-CH3}$$ Then I had to assign priority between the two groups: $$\ce{-CH=CH2}$$ and $$\ce{-CH(CH3)-CH2-...
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Diastereoselectivity of the Pauson Khand Reaction

I hope someone may help me. I don‘t know how to determine the diastereoselectivity of the product of the Pauson Khand reaction in generally. In the following I’ve got 3 practice examples,however in ...
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Enantiomeric excess catalysed

Enantiomeric excess is defined as $$ee = \frac{[R]-[S]}{[R]+[S]}$$ I found this problem in an IChO paper: "When using the enantiomerically pure (BINOL)Al(OiPr) as a catalyst for reduction of ...
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1answer
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How a plane of symmetry makes compounds lose their optical activity

I understand that if a compound has a plane of symmetry it loses its optical activity, it is very easy to understand this when we have four different substituents on a single carbon atom but when we ...
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2answers
119 views

Is there any mathematical or logical proof that carbon with 4 different groups would be chiral?

In chemistry; chirality is generally defined in 2 ways. Lord Kelvin's definition: "I call any geometrical figure, or group of points, chiral, and say it has chirality, if its image in a plane mirror,...
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1answer
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When to permute two times to find optical configuration [closed]

I'm learning about S and R configuration, and I know that in case where the 4th substituant is not behind we should permute it with the one which is behind. then we find the new configuration and use ...
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Confused about inversions in $S_N2$ Reaction

I just learned that in $S_N2$ reaction there is an inversion of configuration. I thought that it is a change of $R$ to $S$ and vice-versa. But that is wrong as mentioned in this answer. While I was ...
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1answer
127 views

Number of stereoisomers of polysubstituted cubane

The molecule given below is a substituted cubane. a) How many stereoisomers exist for this molecule? b) How many pairs of enantiomers are possible? How do I calculate the number of ...
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Finding out more stable conformer via molecular orbital interaction

Out of these two, which one is more stable? I'm unable to imagine the orientation of the lone pairs of O and ABMO of C and Cl bond. Any tips to tackle these kind of problems?
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2answers
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Number of sterioisomers of 2,3,5,6-tetrachloroheptane [closed]

The answer given by Himanshu Pandey in the book Advanced Problems in Organic Chemistry, Chapter Isomerism, Page 76 is 10. But by calculating using the fundamental principle of counting and by viewing ...
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Stereochemistry of C as non-chiral centre

When a C of a molecule is not a chiral centre, the spatial orientation of its substituent group doesn't affect its stereochemical specification, does it? Ex:
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Name of the intermediate in between phosphono and phosphonato group

$\ce{R-PO3^2-}$ is called a phoshonato group (https://www.ebi.ac.uk/chebi/searchId.do?chebiId=30931) $\ce{R-PO3H2}$ is called a phosphono group (https://www.ebi.ac.uk/chebi/searchId.do?chebiId=48108) ...
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1answer
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Which of the Following is Optically Active?

Which of the Following is Optically Active? I understand that for a compound to be optically active, it needs to be chiral and not have any planes of symmetry. I know 1 is symmetric, but I am ...
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213 views

Number of stereoisomers of trisubstituted cyclopentane

When 4-methylcyclopent-1-ene reacts with bromine, then 1,2-dibromo-4-methylcyclopentane forms. And I am stuck on determining the amount of stereoisomers that can form as a result. 1,2-dibromo-4-...
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2answers
148 views

Why do chiral biological molecules only exist as one enantiomer? Does it have any advantage?

Why is it that chiral biological molecules are enantiomerically pure? The other enantiomer would have the same reactivity, and the only difference is their angle of rotation of plane polarized light. ...
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2answers
321 views

Number of optically active compounds among the products of ozonolysis

The number of optically active compound(s) obtained upon complete ozonolysis of the following optically active compound is In the question, I broke all the double bonds and added a $\ce{-CHO}$...
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1answer
236 views

How many products does this reaction yield?

How many products can we get from the monochlorination of 2,4-dimethylpentane including stereoisomerism? I have seen someone say that it yields 3 structural isomers one of which has two enantiomers ...
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1answer
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Why does only the cis-isomer of potassium dioxalatodiaquochromate(III) form?

A friend of mine performed a standard synthesis reaction of potassium dioxalatodiaquochromate(III) by adding potassium dichromate to ethandioic acid dihydrate and a little water. The synthesis ...
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1answer
448 views

Synthesis of an epoxide from 1,2-diol

Why is there no formation of epoxide when the two OH-groups are on different planes? I do understand the epoxidation mechanism. However, I would be grateful if someone cleared the specific ...

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