Questions tagged [isomers]
Compounds that have identical molecular formula but different chemical structure.
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What is the perfect definition for chirality?
Why is chirality defined differently for organic and inorganic compounds?
Why are inorganic compounds deemed to be optically active if they have more than one of the same ligands attached to the ...
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How to determine number of structural isomers?
I have come across many questions where I'm asked to give the number of possible structural isomers. For example number, structural isomers of hexane is 5, while the number structural isomers of ...
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Why is 2-methylpropene less in energy than its alkene counterparts?
Other isomers include 1-butene, cis 2-butene, and trans 2-butene. Why would 2-methylpropene be less in energy if there is more steric hindrance?
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How to assign E/Z configuration according to the Cahn-Ingold-Prelog rules when subsituents differ only by stereochemistry
I stumbled-upon this compound:
I'm wondering how to determine the configuration of the double bond. Is it E or Z? How do I decide on the priorities when the substituents can only differ in the ...
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Relative stability of cis and trans cycloalkenes
Why is the stability of (Z)-cyclodecene 2 greater than that of (E)-cyclodecene 1?
I'd think that since 1 contains a trans double bond instead of a cis double bond, it should experience less steric ...
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Stability of 4-pyridone vs 4-pyridinol
In kryptomerism assignment, there was a question to compare more stable tautomeric form between 4-pyridone (1) and 4-pyridinol (2):
Answer: 4-pyridone.
My friend gave two plausible reasons:
$\ce{C=...
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Are a meso compound and its mirror image isomers?
How are meso isomers even isomers? By definition, meso isomers are compounds that are superposable on their mirror images, but doesn't that mean that the mirror image is just the same compound?
Can ...
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What is metamerism
According to metamerism in polyvalent functional groups, if both alkyl groups' around functional group are different then they are considered as metamers but in few books it is given that if one of ...
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Why do we insert a numeric multiplier after group positions when naming an isomer?
Question: Why do we insert a numeric multiplier after group positions when naming an isomer?
Take 2,3 dimethylbutane for example. Why do we add the numerical ...
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Hydrocarbons with only 4 carbon atoms
How many different organic structures (from the pure theoretical viewpoint) can be drawed with only 4 (exact) carbon atoms and with/without hydrogen? Polycyclic compounds and bridged compounds are ...
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Are methyl n-propyl ether and methyl iso-propyl ether metamers?
Are methyl n-propyl ether and methyl iso-propyl ether metamers?
It says so here.
So the difference must be in number of carbon atoms or the distribution?
Definition(http://dictionary.reference....
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Which is the correct definition for metamers (or metamerism)?
I have heard two definitions of metamers.
Compounds having the same molecular formula but different number of carbon atoms on either side of the functional group.
Compounds having the same molecular ...
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Stereoisomers of octahedral co-ordination compounds of the form [Ma3b3]
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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Why do highly branched alkanes have higher octane numbers than their corresponding linear isomer?
The octane number of fuels are based on a set of primary reference fuels, which are mixtures of iso-octane and n-heptane. Now iso-octane being branched alkane has very less tendency to react and given ...
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How to synthesize 6-methylhept-1-ene
What methods are there to produce this compound? What are its properties as a component of automobile petroleum? How does it impact on detonation resistance of automobile petroleum?
I think that the ...
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What's the difference between alpha-glucose and beta-glucose?
What's the difference between $\alpha$-D-glucose and $\beta$-D-glucose? Are they isomers? Or do they differ in their elemental composition?
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Number of stereoisomers of tetramethylspirononane
The above compound – 2,3,7,8-tetramethylspiro[4.4]nonane – clearly exhibits both optical and geometrical isomerism. The question is, how many stereoisomers does it have in all?
As the number of ...
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What is the reason of the color difference for the cis/trans isomers of tetraamminedichloridocobalt(III) chloride?
The cis and trans isomers of $\ce{[CoCl2(NH3)4]Cl}$ are quite famous as one is purple and the other one is green which is a huge difference in color. Now I can't find any information to why this is ...
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Is there a formula to determine the total number of constitutional isomers?
Is there a trick or a formula that given a molecular formula, allows you to know exactly how many constitutional isomers can be formed with that many atoms? Or is it more of a trial-and-error ...
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Does solvate isomers exist for coordination compounds with ammonia solvent as ligand?
I could find many sources confirming the hydrate isomerism(with water as solvent) but I couldn't find any information about any other solvent. In all the sources "hydrate/solvate isomerism" ...
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Predicting the products of the radical chlorination of propane
Question:
When propane reacts with chlorine, two different monochloropropanes are formed.
a) Name and show the full structural formulae of the two products.
b) What kind of isomerism is shown?
Based ...
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Why tautomers are considered to be the same chemical compound?
Because of the rapid interconversion, tautomers are generally
considered to be the same chemical compound. (Wikipedia)
But looking at the examples provided on that same Wikipedia article, it is ...
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How many stereoisomers are possible for 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane?
How many stereoisomers (not counting different conformers) does 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane have?
I think the answer should be 3. There are two geometrical isomers (cis and ...
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What kind of optical activity requires chirality?
From "Meso compound" in Wikipedia:
A meso compound or meso isomer is a non-optically active member of a
set of stereoisomers, at least two of which are optically active. This
means that despite ...
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Are glucose and galactose cis-trans isomers of each other?
Glucose and galactose are diastereomers of each other. However, is it correct to say that they are cis-trans isomers of each other? Does it make a difference with regard to terminology if glucose and ...
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What is the number of hydrate isomers of chromium(III) chloride hexahydrate?
Assuming $\ce{CoCl3·6H2O}$ is an octahedral complex, the answer should be four as there can be $0, 1, 2$ or $3$ $\ce{Cl-}$ ligands inside the coordination sphere. However, numerous sources say the ...
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How there are 7 enolizable hydrogens in 2‐methylcyclohex‐2‐en‐1‐one?
49. How many enolizable hydrogens are there in the following compound?
(a) 2
(b) 4
(c) 5
(d) 7
I know that enolate ion is the anion formed when an α-hydrogen in the molecule of an aldehyde or ketone ...
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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 enantiomers. I ...
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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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Finding the number of cyclic isomers algorithmically
Is there an algorithm for finding the number of cyclic isomers a given compound might have?
I've found a general algorithm for all isomers: link, but I'm not sure how to apply it for cyclic isomers ...
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Is light a reactant in photochemical reactions?
According to IUPAC a photochemical reaction is a reaction caused by absorption of light. I still can't understand how we should consider light as a part of a reaction. Is a catalyst or a reactant?
In ...
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Difference between Epimers and Diastereomers
My lecture notes describe epimers as compounds which differ by
configuration at only one carbon and gives the example of D-erythrose and D-threose as being epimers.
However isn't that the same thing ...
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Total number of stereoisomers of cyclobutane-1,2,3,4-tetracarboxylic acid
Question
Find all stereoisomers of:
My attempt
I got four isomers, and none of them seem to be optically active as they either have a plane of symmetry or a point of symmetry:
However, my sir keeps ...
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Stability of isomers of N4O
I have googled and found that the structure of $\ce{N4O}$ is linear with a positive and negative charge on 2 nitrogen atoms. But, the following structure seems more stable because it fulfils octet for ...
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Where is bifurcation situated on cyclohexane isomerisation PES?
I am wondering what does PES for cyclohexane isomerisation looks like.
I have two possibilities in mind but each has some kind of vagueness.
1) Starting from boat conformation minimum, followed by ...
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Why is the oxime tautomer more stable than its corresponding nitroso isomer?
We know, generally, that the keto tautomer is more stable than the corresponding enol tautomer. I would appreciate an explanation that goes beyond the thermodynamic reasoning, too.
In the nitroso-...
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Comparing heat of hydrogenation per mole of butenes and 1,3-butadiene
The question asks us to select the compound with the smallest heat of hydrogenation per mole out of the following:
a) 1-butene
b) trans-2-butene
c) cis-2-butene
d) 1,3-butadiene
Since all four ...
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Dehydrobromination of 3-bromo-3-cyclopentylhexane and number of possible alkene products
I faced a question like this:
The total number of alkene products possible from the dehydrobromination of 3-bromo-3-cyclopentylhexane is:
The answer is given 5. But I only found 3.
3-...
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Stability of cis vs trans isomers?
Recently, while reading about isomers I learned that cis isomers are more stable than trans isomers.
I referred many books as well as searched around the internet but I didn't find a suitable ...
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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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Difference between conformational, constitutional, and structural isomers and the same and different molecules
Consider the following sets of problems:
I was hoping someone could clarify what each checkbox means exactly. All of these answers are incorrect (except the first one with the check marks signifies ...
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Constitutional isomers of cis-1,2-dibromocyclopentane
The following is a problem from 'Fundamentals of Organic Chemistry' by McMurry-
Draw two constitutional isomers of cis-1,2-dibromocyclopentane.
Constitutional isomers must have different ...
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Classification in Stereoisomerism [closed]
I was trying to understand stereoisomerism. I am having trouble creating a 'flow chart' of Stereoisomerism. While there are many sources available over the internet and books, I don't find a standard ...
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What are compounds with the same mass called?
It may be that the answer is just "no" and that's why I can't find it, but is there any common name for compounds with the same mass?
I'm thinking in the context of mass spectrometry where these ...
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Why is there only one ionization isomer of [Cr(NH3)5(NO2)]Cl2?
How many isomers are possible for $\ce{[Cr(NH3)5(NO2)]Cl2}$? Consider all possible types of isomerism and draw each isomer.
My texbooks presents only three possible isomers: $\ce{[Cr(NH3)5(NO2)]Cl2}$ ...
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Isomers with molecular formula C₄H₇Cl
What are the possible isomeric structures of chlorobutene $(\ce{C4H7Cl})?$
I've come up with seven:
cis-1-chlorobut-1-ene
trans-1-chlorobut-1-ene
2-chlorobut-1-ene
3-chlorobut-1-ene
1-chlorobut-2-...
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State of a Racemic Mixture
Is a racemic mixture always an equi-molar solution of two enantiomers, both in the same state? Is it necessary for both isomers to be in the liquid state for racemisation to occur, or does ...
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How many ether metamers are possible for C4H10O?
How many ether metamers are possible for $\ce{C4H10O}?$
According to me, the answer should be 2 but it was given 3. I know 3 structures can be made:
$$\ce{CH3—O—CH2—CH2—CH3}\tag{1}$$
$$\ce{CH3—CH2—...
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Total number of stereoisomers of 2,3,5,6-tetrachlorooctane
Total number of stereoisomers for:
I tried the following combinations:
RRRR, SSSS, RRRS, SSSR, RRSS, RSRS, SRRS, RSSR, RSRR, SRSS, RRSR, SSRS, SSRR, SRSR.
So, total number of stereoisomers I got is ...
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What is the difference between the structure of nitrito-O and nitrito-N?
I am preparing for chemistry olympiad and I am stuck nitrito-O and nitrito-N. Can anyone explain difference between the structure of nitrito-O and nitrito-N or point a resource which is suitable for a ...
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