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Questions tagged [isomers]

Compounds that have identical molecular formula but different chemical structure.

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Conformation isomers

I read that conformers have different configuration due tomorrow rotation of a molecular with respect to an axis. I have a doubt regarding the classification of conformers into staggered,eclipsed,...
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Hydrate isomerism

My book specifically mentions in the solution to a question: $\ce{[CrBrCl2 (H2O) (NH3)2].H2O}$ is not the hydrate isomer of $\ce{[CrCl2 (H2O)2 (NH3)2]Br}$ But the author hasn't provided any ...
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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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Why does 1,3-dichloropropane not show stereoisomerism?

It is a multiple choice question: Which compound does not show stereoisomerism? A 1,2-dichloroprop-1-ene B 1,2-dichloropropane C 1,3-dichloroprop-1-ene D 1,3-dichloropropane I ...
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Please help me find the isomers of this compound

I've been all around the internet and I still don't get it. The question asks me to write all the possible isomers and classify them as positional/chain/... By pairs..... I look at the question and ...
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Can the CDK represent a mixture of stereoisomers

Biovia (previously MDL) Enhanced Stereochemical Representation enabled specifying mixtures of enantomiers by annotating sterocenters with a group and one of these types: ABSOLUTE: Stereogenic ...
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Are Anomers Epimers?

epimers are the class of stereoisomers which differ along configuration at any carbon in a carbohydrate(generally), And anomers are the kind of stereo isomers that differ at the carbonylic carbon, ...
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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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If a chiral molecule reacts with an achiral molecule will the product be chiral or achiral?

My book says that a pair of enantiomers will react the same way with an achiral substance. How is this possible? Does this imply that the product is achiral, even though the enantiomers are chiral? ...
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Number of spatial arrangements of tetrasubstituted biphenyl

According to my book 2-bromo-2'-(1-chloroethyl)-6'-iodo-6-(prop-1-en-1-yl)-1,1'-biphenyl has eight possible spatial arrangements. How can this be so? I can think of only four – left two groups being ...
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1answer
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Ortho vs para alkylation of chlorobenzene

I have a question to the solution regarding the product formed in a reaction with chlorobenzene with the use of (i) $\ce{CH3CH2Cl}$ and (ii)$ \ce{AlCl3}$. Since the -Cl substituent is ortho- para-...
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1answer
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why do the complex [Cu(NH3)5NO2]SO4 show ionisation isomerism?

In ionisation isomerism, secondary valencies can be replaced by primary valencies on the condition that net charge going outside the coordination sphere must be equal to net charge coming inside it . ...
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How are there only 8 structural isomers of C5H11Br?

Everywhere I see mentioned, that there are only 8 structural isomers of $\ce{C5H11Br}$. That is, the simple $\ce{C5}$ straight chain, $\ce{C4}$ with substituted methyl and $\ce{C3}$ with two ...
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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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1answer
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Why are some strucutres isomers while others are not? [closed]

Why are some structures considered isomers but others are not? Take C3H9N for instance, according to https://www.chegg.com/homework-help/questions-and-answers/four-constitutional-isomers-molecular-...
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Explain optical activity in Biphenyl compounds

How is optical activity explained in biphenyl compounds using atropisomerism. NOTE: I was taught that if vertical symmetry exists then optical activity is not shown by any substituted biphenyl ...
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What are the metamers of penta-1,2-diene?

First of all, are there any metamers for dienes? If there are any, how can I find them?
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1answer
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Are ortho, meta and para used in IUPAC nomenclature?

I was presented with the following question in an online test: To avoid any confusion, here are the arranged options: A. 2-Chlorotoluene B. 1-Chloro-2-methylbenzene C. B and D D. O-...
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1answer
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Systematic Approach to Finding Number of Isomers [duplicate]

I have this compound I want to know how many isomers (including stereoisomers) may have this constitution. Is there a systematic approach towards solving such types of problems related to the total ...
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1answer
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No.of isomeric ethers of formula C3H6O

I managed to get 3 ethers:- 1.4-member ring ether(Oxetane) 2.Vinyl ether 3. Epoxy ether This question was asked in my school exam and the teacher had given its answer as 4..Could anyone please tell ...
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Number of total stereoisomers of a piperazine derivative

How do I find out the total number of stereoisomers of 3,6-dimethylpiperazine-2,5-dione? As far as I can see, the compound has two chiral carbons. Would the nitrogens make a difference? They seem ...
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Does dihydroimidazole show geometrical isomerism?

Does dihydroimidazole (above) exhibit geometrical isomerism? Does the fact that the lone pair is involved in conjugation with a double bond affect anything? As far as I know, it does not exhibit ...
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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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Reactivity of different isomers of N2F2

$\ce{ N2F2}$ exists in two forms cis and trans. Today my chemistry teacher tells me that among the two only cis form takes part in reactions and that it is more reactive. But I have read elsewhere ...
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Is 3,4-diethyl-3-hexene cis or trans? [closed]

I'd really appreciate it if someone could explain this one, please! According to my answers sheet it is not cis nor trans. But it looks like it is cis? Why, according to my answers sheet, is this ...
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1answer
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What is it meant by two different groups in stereoisomerism?

I understand there are some properties in an organic compound that allow stereoisomerism. double bond can't rotate two double bonded carbon atoms each have two different atoms or groups attached I'm ...
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Difference in alpha and beta glycosidic bonds [duplicate]

I have learned that the cellulose has a much rigid and orderly branched structure than the starch. However, the only significant difference between them is the different type of bond formed after ...
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1answer
305 views

Structural isomers given a molar mass [closed]

How many structural isomers are possible for compound containing $\ce{C}$, $\ce{H}$ and $\ce{O}$ atoms only with their molar masses $100$ as well as the isomers are simultaneously ketones 3 ...
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2answers
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Why are conformational isomers considered as isomers?

I was taught that geometric (cis-trans) isomers are considered isomers because there is a high energy barrier to breaking the double bond for rotation (to convert into the other isomer). Given that ...
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1answer
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Why dichlorobenzene doesn't show geometrical(cis/trans) isomerism? [duplicate]

As it has restricted rotation due to the presence of a double bond, it should show geometrical isomerism. Then, why doesn't it show cis/trans isomerism?
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1answer
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Why is mer-AlQ3 more stable than fac-Alq3?

Several research papers and books say that the meridional isomer of tris-(8-hydroxyquinoline) aluminium is thermodynamically more stable than the facial isomer. What is the reason behind this ...
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Coordination isomerism variation

The school book and Wikipedia state that coordination isomers are: In a coordination isomer the total ratio of ligand to metal remains the same, but the ligands attached to a specific metal ion ...
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1answer
350 views

Conditions for Chirality in optical isomerism [duplicate]

Is it necessary that any atoms which is chiral must have 4 different atoms around the central chiral atom(maybe it can be carbon if it's organic molecule) bonded to it? More specifically: I mean can't ...
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263 views

Hydration Isomerism in Cr(III) and Co(III) [closed]

Cr(III) and according to a paper I found also Co(III) are famous for the property called hydration isomerism. I already asked about how changes in the environment of a complex, for example temperature ...
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Which of the following is more stable?

In this image, does the arrows indicate correct rate of reactions? The upper arrow is longer and lower is shorter. According to me Chair is more stable than Twist Boat. Does axial and equatorial ...
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Why does dichloridobisethylenediaminecobalt(III) have only three optical isomers?

Sorry for the bad drawing and having $\ce{NH}$ instead of $\ce{NH2}$ In the first structure, the chlorine atoms are in trans position on the plane. In the second structure, the chlorine atoms are ...
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Why does the keto tautomer of guanine have lower energy?

Looking at the keto and enol forms of guanine, it would seem as if the enol form is more stable, due to the fact that aromaticity is established with the enol form. However, according to a question on ...
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1answer
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How can a Hydrogen make such a difference?

Looking at familiar bodily fluids for a learning session. At first glance they both look the same. Then I noticed the N=C in biliverdin and HN-C in bilirubin. How can a N=C (imine group) and HN-C (...
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How are these two organic resonance structures different?

I've been working through some questions online (self study, not homework) predicting the various forms for molecules. One of the questions involved the following molecule (see image below). It had ...
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2answers
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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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2answers
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Why does having identical groups on either side of the pi bond lead to no geometrical isomerism?

As far as I was taught, cis and trans isomers were categorised under stereoisomers and sub category of geometric isomers. Qualifying properties like, rigid and restricted double bond rotation (due to ...
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1answer
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Are benzyl alcohol and o-cresol functional isomers or position isomers?

My textbook categorizes them as functional isomers (phenol and aromatic alcohol) whereas The above mentioned isomers are given as position isomers on 'chemguide.co.uk'
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Number of isomers in a 3-sugar oligosaccharide

I recently read that 12288 different oligosaccharides can be formed from the D-isomers of glucose, mannose and galactose. I wanted to try to calculate this, but I keep falling very short of this ...
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2answers
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How to determine if an alkene is an E or Z isomer?

Is the molecule below an E or Z isomer? From what I believe I would say E isomer because the two priority halides Cl and Br are on opposite sides of the double bond. But I'm not 100% sure. Because ...
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1answer
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How many cis-trans isomers does 1-O-stearoyl-2-O-arachidonyl-phosphatidyl-inositol-4',5'-bisphosphate have?

I saw an exam that had a question asking the number of cis-trans-isomers of 1-O-stearoyl-2-O-arakidonyl-phosphatidyl-inositol-4',5'-bisphosphate: The "correct" answer in the exam is 1023, but this is ...
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1answer
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Number of cyclic isomers of C4H6 [duplicate]

I faced a question How many cyclic isomers are possible for $\ce{C4H6}$? I and my friend found the following four. But the answer key says there are 5. So what's the other one?
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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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How do you predict isomers for certain hydrocarbons? [duplicate]

Hexane $\ce{C6H14}$ has 5 isomers, but I'm able to draw at least 6 different structures, which initially led me to think that there were 6 isomers. So how can I tell which structure will qualify as ...
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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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1answer
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Difficulty in cis, trans isomers in Alkene [closed]

I have a difficulty in appointing cis trans isomer to an Alkene compound . I have looked it up and drawn out a few - Which "point" should I look at to understand in order to allocate cis and trans ...