Questions tagged [isomers]

Compounds that have identical molecular formula but different chemical structure.

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1answer
157 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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How many functional isomers does propionic acid have? [closed]

I need to know how many functional isomers does propionic acid have. Chemical formula is CH3CH2COOH. I also need to know their structural formula, and the names of the isomers. Thanks!
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1answer
45 views

Does tris(ethylenediamine)iron(III) exhibit optical isomerism? [closed]

I'm studying 12th. In my book they mentioned that $\ce{[Co(en)3]^3+}$ exhibits optical isomerism. But in that same book, there is a question Which of this doesn't exhibit isomerism? and the ...
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Why are branched isomers less polarisable?

This fact was given as an explanation as to why branched isomers of a compound have lower boiling points. How are branched isomers less polarisable and how does this relate to London dispersion ...
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0answers
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Do any pharmaceuticals increase in potency or toxicity over time?

Pursuing a question raised in these comments: Are there any known pharmaceuticals that increase in potency or toxicity during storage, or over periods of months to years? If not, what if we broaden ...
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17 views

Why are these compounds classified as metamers? [duplicate]

Metamers are compounds having the same molecular formula but different number of carbon atoms, on either side of functional group. In the above compounds, the number of carbon atoms around the ester ...
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1answer
111 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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128 views

How many isomers are there of dimethylcyclopentane ( neglecting enantiomers )?

The book says the answer is 5 but i was able to draw much more than that like Methylcyclohexane ,propylcyclobutane ,1-Ethyl-2-methylcyclobutane ,1-Ethyl-2,3-dimethylcyclopropane,1-Methyl-2-...
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1answer
62 views

The number of optical isomers of 3,4-dichlorobutan-2-ol

The number of optical isomers possible for the given organic molecule is? $\ce{CH_3-C^*H(OH)-CHCl-CH_2Cl}$ (the configuration is fixed at $\ce{C^*}$) The given answer is 2. The carbon marked with an ...
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3answers
299 views

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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1answer
72 views

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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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. ...
5
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1answer
276 views

What is the physical state of vitamin E acetate at room temperature and normal pressure

Vitamin E acetate ((+)-alpha-tocopherol acetate) is sold as semi-solid/liquid by Sigma and their safety data sheet gives the melting point as 25 °C. On the other hand, internet databases such as ...
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2answers
72 views

Why are we still using cis/trans system while the E/Z system is better than it?

I am currently learning about Alkenes. It is given that cis/trans isomerism is either ambiguous or doesn't even apply in cases where the alkene is trisubstituted or tetrasubstituted. To solve this ...
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1answer
403 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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486 views

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 ...
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1answer
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how is there no centre of symmetry in this case? [closed]

the question was whether the following compounds have the center of symmetry or not .the question was : And the answer is that there is no center of symmetry .how? according to me, there should be ...
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1answer
321 views

Point group of cis- and trans-decalin

What is the point group of of cis- and trans-decalin? I watched a video saying that it is $C_\mathrm{2h}$ for cis-isomer, but my friend says it is $D_\mathrm{2h}.$ I'm so confused.
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799 views

what will be the priority order?

if any two compounds happen to show tautomerism, ring chain isomerism, functional isomerism, metamerism, chain isomerism as well as position isomerism, what priority order do we follow to assign them ...
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278 views

How ethylbenzene and 1,2‐xylene are chain isomers?

How the following two structures are chain isomers? According to what I have studied in nomenclature when a compound has both cyclic and straight chain, we consider that the chain as parent chain ...
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2answers
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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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How would you order alkyl groups of this compound numerically? [closed]

If akyl groups are ordered alphabetically and ethyl comes before methyl, would this compound be called 2-ethyl-3,4 dimethyl pentane? Since that would be less than 4-ethyl-2,3 dimethyl pentane, correct?...
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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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3answers
168 views

Identify the type of structural isomerism

Question: My Approach: Since both the compounds have the same principal functional group, they can't be functional isomers. Obviously they are different compounds. Now options A and C are ruled out. ...
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1answer
272 views

Doubt in conditions for geometrical isomerism

In my textbook, under the topic "Conditions for geometrical isomerism", the following has been given: Groups responsible to show geometrical isomerism must be nearly in the same plane. Is this ...
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363 views

Finding structural isomers of an alkene

I am doing problems on finding structural isomers. I am asked to find the structural isomers of $\ce{C5H10}$. The answer to problem states there are 10 structural isomers possible. I was able to find ...
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Plaster of Paris

One of my Chemistry professors said that the hard mass formed after adding water to Plaster of Paris, cannot be converted back into Plaster of Paris. However, he said that the original Gypsum can be ...
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1answer
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Are these chemical reactions with amino acids possible, and if so, what are they called?

In high school, I am taught that the synthesis of two amino acids of the form $\ce{H2NR1COOH}$ and $\ce{H2NR2COOH}$ is a condensation reaction that produces a polypeptide $$\ce{H2NR1COOH}+\ce{...
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1answer
112 views

Doubt in isomerism

Question Give isomeric relations between these compounds. My answer A and B show metamerism and positional isomerism. A and C show chain isomerism and metamerism. B and C show chain ...
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1answer
192 views

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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1answer
252 views

What are the isomers of a complex having a structure of M(AB)2C2?

Our instructor have us answer an isomerism problem of a crystal structure that has a form of $\ce{M(AB)2C2}$. I keep getting 9 isomers, which includes the optically inactive isomer, and my peers and I ...
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1answer
2k views

What is the total number of isomers, considering both structural and stereoisomers of cyclic ethers with the molecular formula C4H8O?

According to me, it should be 11 and this is how I have worked out as shown in the attached diagram. However, I am not sure whether all these 11 isomers can be considered as those belonging to ...
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165 views

Which is more stable: isobutylene or cis-2‐butene?

How do you compare which is more stable without using the heat of hydrogenation or combustion or any other numeric factual value: $\ce{(CH3)2-C=CH2}$ or $\ce{CH3-CH=CH-CH3}$ (cis)?
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1answer
364 views

The maximum no. of isomers (including stereoisomers) that are possible on mono-chlorination of the compound: 3,3-dimethylpentane is?

The maximum no. of isomers (including stereoisomers) that are possible on mono-chlorination of the compound: 3,3-dimethylpentane is? The answer given is 5. My working: The fourth carbon is chiral ...
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1answer
282 views

How do we know if this following molecule is a superimposable mirror image or non-superimposable mirror image ? [See Image attached]

How do we know if this following molecule is Super Imposable mirror image or Non Super Imposable mirror image ? [See Image attached]
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Which of the following compounds is NOT an isomer? [closed]

Which of the following compunds is not an isomer? I cant figure out how the answer is d
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Why do tetrahedral organic molecules show stereo-isomerism, but not tetrahedral transition metal complexes?

Both types of molecules show different arrangements of the molecule in space, so they should qualify for optical isomerism right?
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1answer
241 views

Confused between structural isomers versus stereoisomerism

So this question wanted me to find two cyclical compounds that are 'structural' isomers of the molecular formula given in the question. The two isomers I came up with are: 1,2-dichlorocyclopropane ...
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1answer
135 views

Cis and Trans Isomerism given three different groups around the reference plane

In the following problem I am meant to deduce the molecules that are cis-trans isomers of each other. This question does not make much sense in my head because I thought that cis/trans isomerism was ...
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1answer
206 views

What is the name of “cis/trans” isomerism when all four groups are different?

How would you call a pair of isomers on the picture below? They look a lot like regular cis/trans isomers, except all four groups are different. I can tell they are spacial isomers (stereoisomers) ...
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1answer
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Interchangeable isomers [closed]

I am a clinical research professional. I have a question regarding clinical chemistry. I would like to know that whether it is possible to get testosterone undecanoate from ursolic acid and vice-versa ...
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0answers
86 views

The van't Hoff rule for stereoisomers with planes of symmetry

We know that the maximum possible numbers of stereoisomers of a molecule is given by the van't Hoff rule, which says that: $$Total \space stereoisomers = 2^{n}$$ Where $n$ is the number of ...
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0answers
55 views

What does the dissociative mechanism for cis/trans interconversion of [Mo(CO)4(PPh3)2] look like?

All I can find in the literature is that the cis→trans interconversion proceeds via dissociation of one of the PPh3 ligands resulting in a square-pyramidal Cs intermediate, with the remaining PPh3 in ...
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3answers
554 views

Why are carbons of Inositol chiral centers?

I was asked to draw all possible stereoisomers of inositol (1,2,3,4,5,6-cyclohexanehexol). To obtain the answer I had to assume that all six carbons of the molecule are asymmetric, which (bearing in ...
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2answers
264 views

Melting point of unsymmetrical dimethylhydrazine vs 1,2-dimethylhydrazine

Unsymmetrical dimethylhydrazine ($\ce{H2NN(CH3)2}$) has a melting point of −57 °C, but its isomer, 1,2-dimethylhydrazine ($\ce{(CH3NH)2}$) has a melting point of −9 °C. That looks to me like a ...
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102 views

ionisation isomers [closed]

With ionisation isomers, how do you know which ligand (out of $\ce{Br}$ and $\ce{NH3}$ for example) exchanges with the compound outside the bracket?

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