Refers to the spatial arrangement of atoms in a chemical entity.

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Isomers of co-ordination compounds

Does $\ce{[Co(H2O)3Br3]}$ show geometrical and optical isomerism? According to me $\ce{Co}$ should be $\mathrm{sp^3d^2}$ hybridised giving an octahedral geometry. It is of the form $\ce{Ma3b3}$ type. ...
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53 views

Is it true that human cells grow in levorotation? [closed]

I remember reading this in a popular science magazine, some 20 years ago: that in most of the living organisms, cells grow in levorotation and very few grow in dextrorotation. Is that true, at least ...
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Which nutrients in food have cis/trans isomerism? [closed]

Which of the classes of nutrients in the food we ingest (vitamins, sugars, proteins, fats, cholesterol, etc.) have members that exhibit cis/trans isomerism?
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48 views

Optical isomerism regarding diastereomers

Are diasteriomers always optically active? If not then why? Though they are chiral then also.
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85 views

What is the difference between D and L configuration, and + and -?

What is the difference between D and L configuration, and + and -? My textbook says they are two different things. It also says that the correct way to name glucose is D(+)-glucose. Could someone ...
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22 views

isomerism in coordination complexes

Is there any difference between geometrical and cis-trans isomerism in coordination complexes, because in my book it is given that complexes of the form [Ma4bc] does not show cis-trans isomerism but ...
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25 views

Why does a compound need to have a Hydrogen attached to the Carbon, in order for the racemization to happen with the help of a base?

Acids and Bases accelerate the enolisation process, and help also the racemisation process. But, in the compounds that don't contain a hydrogen atom attached to the chiral carbon, for example ...
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69 views

Masamune's rule of diastereoselectivity multiplicity

In a reaction between a chiral substrate and chiral reagent, their asymmetric inductions could cooperate (matched pairs) or compete (mismatched pair). According to Masamune, in a matched pair the ...
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26 views

Examples from everyday life for diastereoisomers ?

Like the amino-acids and sugars that are enantiomers, can you give any examples of diastereoisomers ? where can we find them in everyday life ?
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25 views

Are isomers and stereoisomers the same thing?

I am doing a presentation regarding Stereochemistry, and I am a little confused with the terminology. My question is: Are isomers and stereoisomers the same thing? Do they differ from each other?
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71 views

Heat of combustion of stereoisomers of 1-tert-butyl-2,4-dimethylcyclohexane

Which of the compounds below has the smallest heat of combustion? I know that the heat of combustion is indirectly proportional to the stability of a molecule. And here both $\ce{CH3}$ and ...
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is a coordination compound of type MA5B optically active?

In a coordination compound the central atom is connected to 5 same type of atoms and 1 different in an octahedral configuration. Why is it optically active as per my book?
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Why is H bonded to C5 drawn below the plane in Haworth formula for D-glucose?

I have always seen the hydrogen atom bonded to C5 drawn below the plane as in the following figure. Shouldn't it be drawn above the plane since it is drawn on left side in Fischer projection?
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Are these two structures of 1,3-dichlorocyclobutane enantiomers?

According to me they are not enantiomers because the mirror image can be rotated by $180^\circ$ to get the same compound. Giving it a little more 3-D look: But the book says they are ...
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31 views

Different types of bond

In the diagram below shown, I saw that there are different types of bond between the ring and CH3. What type of bonds are they? Are they not a single bond?
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71 views

Hyperconjugation vs. steric hindrance: which is stronger?

If we talk about a series of molecules: ethene, prop-1-ene, but-2-ene, etc., we see both hyperconjugation (which increases stability) and steric hindrance (which decreases stability). So which one is ...
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124 views

Are the following molecules chiral or not?

The molecules 1-7 are drawn below: My idea is that 1, 2, 5 and 7 are chiral, whereas the others are achiral. 1's stereocentre is labelled 'S'. 2's mirror image cannot be superimposed, but 3's can. ...
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Enantiomerically pure ketone reaction under acidic conditions gives 1:1 mixture of diastereoisomers?

My problem is such: My thinking is that perhaps the explanation has something to do with the carbonyl group being prochiral and having two faces, each side generating one of two diastereoisomers? ...
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56 views

Neighbouring group participation with and without retention of configuration in nucleophilic substitution of 2,6-dichloro-9-thiabicyclo[3.3.1]nonane

I am having difficulty drawing out the inversion ring product to find out if the $\ce{S}$ lone pair can attack from anti to the $\ce{C-Cl}$ σ* bond on the vertical ring … If it does then, ...
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106 views

Bromination of Phenylacetone

Looking at the following reaction, I understand how the product forms, however, can somebody help me understand why two products are formed? Would the identical mechanism produce the two products? ...
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26 views

Why is the antibonding pi bond higher in energy than the normal pi bond?

In my book, Organic Stereochemistry, the following picture is shown: In the lowest diagram, in Figure 1.3, which shows a π* bond, the positive lobe of the p orbital of atom A is nearest to the ...
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103 views

Stereoisomerism in cyclic compound

In 1,2-Cyclobutanediol it's written in the book that it has 3 stereo isomers. Here's the passage - I can't imagine how it can have stereo-isomers since and how the meso compounds will look.
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Finding R and S configuration in Fischer Projection

I have all the rules of Fischer projections figured out. But, when the problem asks for finding the configuration of a molecule with 1 chiral carbon and in a Fischer projection form, do we need first ...
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50 views

Diastereoisomer of quinic acid and its proton NMR?

The question is such: Quinic acid, A, has the gross structure shown below: (i) Draw all the possible diastereoisomers of A and indicate which are chiral. (ii) Quinic acid is optically ...
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170 views

How to determine optical activity of a compound without asymmetric carbons theoretically? [closed]

I know that a compound doesn't need to have a chiral carbon to be optically active. So how can I find out whether a compound drawn on paper is chiral without access to any experiments? e.g. ...
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55 views

Use of combinations to determine number of isomers

Our teacher asked us how many geometrical isomers are possible with the formula $\ce{c2ClBrIf}$. I answered with the logic $^4C_2=6$ and it turned out to be correct. Is the use of combinations this ...
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Cis and trans substituents on rings different stereodescriptors

The attached two compounds are diastereomers. They can be differentiated by cis/trans descriptors. Is there another way of describing them as cis/trans seems to be outdated? EDIT: How to determine ...
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34 views

What is the relationship between configuration & optical rotation?

Is there a clear cut rule between the two? For example, is R always (+), or is S always (-), or is there no relationship? And if so, why? Wouldn't it make sense that plane polarized light would rotate ...
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33 views

Unsaturated alcohol configuration

The molecule is such: My working is such: But my supervisor said the molecule is actually R configuration. Could someone please explain this and tell me where I went wrong?
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Stereochemical outcome after elimination followed by addition

One of the following diastereomeric chlorides undergoes racemisation on heating whilst the other is returned unchanged. Explain. From the reaction conditions I can see that there must be ...
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57 views

Tables/database/literature of specific or optical rotation

I'm looking for a comprehensive reference of experimental specific rotation or optical rotation data. It can be a published literature review, a free web database with API access or one that permits ...
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1answer
63 views

Stereoselective but produces enantiomers?

I think I have my terms mixed up but I'm confused about the concept of stereoselectivity as they relate to reactions with alkenes. For example, hydroboration is a stereoselective reaction. It uses ...
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64 views

Hydroboration mechanism, confusion about product formed

honestly I can't see why b and c are there -- it seems like b and c are diastereomers but I can't see why one would be favored over the other. Am I missing something? I've tried the last answer too ...
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How to determine the configuration of C atom bounded to two groups with same configuration? [duplicate]

What is the configuration of the central C atom in the following molecule and how to determine it?
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42 views

Account for the differences in Gibbs energies of activations for the rotations about the bond indicated

Why is there a difference in energy? My reasoning is such: Due to conjugation between the O electrons and the pi- double bonds, the bond has actually single bond characteristics and is therefore ...
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1answer
46 views

Radical Bromination of a 1-isopropyl-4-methylcyclohexane

I'm considering a problem whereby 1-isopropyl-4-methylcyclohexane with the indicated stereochemistry shown undergoes radical bromination at the indicated position. I understand there are other ...
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1answer
63 views

Deciphering stereochemical notation in electrocylization reaction

I not agree with this solution, for me the red bond formed must be a dotted line in the drawing, and the hydrogen atom musn't be represent with a dot. Am I right or not?
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Stereochemistry of hydrogenation with Raney nickel

If I react the following with Raney nickel and $\ce{H2}$, $\hspace{65 mm}$ then I am getting a meso compound, as the $\ce{H-}$ anion will have anti addition, right? One $\ce{H}$ will attack on right ...
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158 views

How is the Felkin-Anh model of stereoinduction correctly explained with MO theory?

One method to predict stereoinduction in asymmetric reactions is the Felkin-Anh model (derived from the more basic Cram model) that applies to nucleophile attacks on α-chiral aldehydes. In a ...
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What symmetry elements mustn't a molecule possess to be considered achiral?

Undergraduate textbooks say that a molecule mustn't posses a reflection plane and an inversion center to be considered achiral. As mentioned by Ron in his answer to this question, molecules that don't ...
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How to interpret the rate constants of in-vivo racemization of thalidomide?

The article by Eriksson et. al. found that thalidomide undergoes chiral inversion in vivo. It found the mean rate constants too, $0.17~\mathrm{h^{-1}}$ (R to S) and $0.12~\mathrm{h^{-1}}$ (S to R). ...
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43 views

How many stereoisomers of this compound are there?

What is the total number of stereoisomer of this compound? 2 4 8 16 As there is only 1 chiral carbon, and 2 out of 4 C=C double bonds that contribute to geometric isomerism (cis/trans), I think ...
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Using CIP rules in bicyclic compounds

In the given compound, arrange the numbered groups according to CIP rules: Group $1$ will have highest priority because Oxygen atom is attached to $1$. (It can be considered as two oxygen atoms). ...
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is this the proper identification of this cyclic molecule?

Attempt: (1S,3S)-1,3-Dichlorocyclohexane I'm just not sure about the nomenclature for R and S configurations (our teacher was a little unclear). I gave it my best shot after looking through some ...
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29 views

is my reasoning for enantiomers/meso compounds correct?

I think a and b are enantiomers because a has R configuration but b has S configuration. I think c and d are identical compounds which makes them a meso compound. If you just turn it 180 degrees ...
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48 views

Confusion on enantiomers and meso compounds

Question: Are these compounds enantiomers? Attempt: The compounds given are mirror images. But if I rotated the three bonds in the third carbon (configuration will not change), I will get a meso ...
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Detect the presence of non stereochemically annotated atoms in mol files

I'm facing a problem now and I don't know where to start from. I'm treating databases in which there are mol-files that have stereo-chemical carbons, which, sometime, are not annotated as being R/S or ...
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265 views

Does trans 1,3-dichlorocyclobutane have zero dipole moment?

Does this compound have zero dipole moment? I think it has a non-zero dipole moment. If I assume the ring to be planar, then the dipole moments of each $\ce{C-Cl}$ bond cancel out. (One is upward ...
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42 views

Is it incorrect to use Fisher Projections for carbons that don't have stereocenters?

For example: Is a cross specifically used for stereocenter representation?
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How to determine the stereochemistry of a compound with a carboxylic group and an ortho carboxylic acid bound to the same carbon of a double bond?

Is this E or Z? According to my organic chemistry teacher it's E. According to tutors and other students it's Z. What is the correct answer?