Questions tagged [geometrical-isomerism]

Also known as cis/trans isomerism, configurational isomerism, or E/Z isomerism when referring to alkenes.

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Does 1,3‐dichloroallene show geometrical isomerism? [duplicate]

Since the attached groups are present in different planes, $\ce{ClCH=C=CHCl}$ should not show geometrical isomerism, but my book say that it does. Why?
2
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0answers
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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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1answer
84 views

E - Z configuration of cyclic substituents [closed]

The answer is coming out as Z but given is E. I’m not sure where I’m wrong at this point as I moved along one chain at a time and wanted to follow heaviest atom as earliest as possible !
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1answer
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Please explain plane of symmetry [closed]

i am getting option (a) but answer is (b) where i am going wrong please help SO IT IS OPTION A ONLY FOR ME BUT HOW B HAS PLANE OF SYMMETRY PLEASE HELP
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1answer
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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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1answer
166 views

Total Structural Isomers of diphenyl chloromethane?

The maximum option is 8 available but while Drawing I found there are many more . Are there any other condition of structural formula except the fact that the compounds will have the same molecular ...
2
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2answers
863 views

Stability of geometrical isomers in cycloalkanes

Among the following, which should be the most stable compound? 1)Cis-cyclohexane-1,2-diol 2)Trans-cyclohexane-1,2-diol 3)Cis-cyclohexane-1,3-diol 4)Trans-cyclohexane-1,3-diol My thought process is-...
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1answer
377 views

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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1answer
556 views

Geometric isomerism in substituted cycloalkenes?

My book says the first and third molecules only will show geometrical isomerism. Why is this so? I can understand how the third will show (both the methyl groups can be into the screen or one can be ...
2
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1answer
381 views

Number of geometrical isomers?

How many geometrical isomers will exist for compound of this type which has cycloalkene having carbon atoms greater or equal to 8 in the middle of chain? I know that due to ring in middle of chain ...
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3answers
347 views

Melting point of trans-4-methylhex-4-enoic acid and cis-4-methylhex-4-enoic acid

My book said that the cis isomer has a higher melting point. But I dont understand isn't that the trans isomer can pack more efficiently, because the trans isomer less bulky/ create less 'kink' than ...
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1answer
157 views

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 ...
2
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0answers
153 views

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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2answers
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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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1answer
156 views

What is the relation between the following two optical isomers?

I think they should be diastereomers, but the answer to this question is enantiomers, if it is enantiomers then how?
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2answers
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Why is cis-1,2-dichloroethene more stable than trans-1,2-dichloroethene?

Why is cis-1,2-dichloroethene more stable than trans-1,2-dichloroethene? Usually, trans compunds are more stable than cis ones, due to less strain and its non-polarity. But, in this case it's quite ...
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2answers
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Does CHT=CHT have a geometric isomerism because of tritium atoms?

Is the radioisotope of hydrogen considered as a new atom? Can you detect it with an H NMR?
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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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1answer
466 views

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
674 views

Why is tautomers not possible in benzoquinone? [closed]

1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula $\ce{C6H4O2}$ When there are alpha Hydrogen's why can't it show tautomerism?
4
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1answer
174 views

Does 1-ethylidene-2-(propan-2-ylidene)cyclobutane show geometrical isomerism?

I think it should be yes, but my book says no. I think the two geometrical isomers are Z-isomer E-isomer
2
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1answer
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Is a carbon chiral it two of its groups are cis - trans isomers? [duplicate]

For example: In this image, the two groups sticking to a carbon are cis-trans isomers. So does that make the carbon chiral, exhibiting optical properties? What if the two groups were both having ...
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3answers
684 views

Why does 1,3-dimethylcyclopent-1-ene have geometric isomerism while 1-bromo-2-chlorobenzene doesn't?

The bottom compound has bromine and an R group connected to one of its SP2 double bond carbons, and chlorine and the same R group connected to the other. This fact, it would seem, indicates cis-trans ...
3
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0answers
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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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0answers
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Geometric isomers of substituted methylidenecyclohexane?

My thoughts on the problem: I am sort compound of sure C and D will not show geometric isomerism because of the same groups (H and H) attached. In compound A and B, suppose I swap the positions of H ...
2
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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 ...
5
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1answer
663 views

Determining geometry of trisubstituted alkene

The way I know to tell whether an alkene is E or Z -is to look at the coupling constant of the protons across the doble bond. Large value (16 Hz) indicates an (E)-alkene where as smaller values (11 Hz)...
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1answer
130 views

Can cis and trans isomers have widely different flash points?

Sigma seems to have two products listed for sale as "Cinnamic Aldehyde". One compound clearly seems the trans isomer but the other one seems like an unspecified mixture. (They even have two different ...
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2answers
530 views

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 ...
5
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0answers
58 views

What theoretically is the smallest cyclic trans hydrocarbon to correspond to a local potential energy minimum?

Trans-cyclooctene is isolatable at room temperature. Trans-cycloheptene is also known at low temperature. Ab Initio Conformational Analysis of trans-Cyclohexene (1995) says that there is ...
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1answer
477 views

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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3answers
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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 ...
5
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1answer
412 views

Why does steric hindrance cause a d8 complex to have a tetrahedral geometry rather than a square planar geometry?

I'm currently working on a question based on two isomers of a nickel complex, where nickel exists in the oxidation state Ni(II) (i.e. has d-electron configuration $d^8$). It has been deduced that the "...
6
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1answer
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The number of geometrical isomers of complex of type [Ma3b2c]

The question is to find out the number of geometrical isomers of the complex $\ce{[Ma_3b_2c]}$. I applied simple combinations to get the number of isomers as $\Large\frac{6!}{3!2!}$ which is 60 in ...
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0answers
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Is rotation/flip of skeletal structural formula of Sildenafil/Claim 6 okay?

I want to show visually the similarities between Sildenafil (Viagra) and the molecule on the right: Is it allowed to flip the skeletal structural formula and rotate bond strings of the molecule on ...
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1answer
137 views

Why is this molecule considered a cis isomer of 2-bromobut-2-ene?

I know that we have two CH3 groups on one side and restricted rotation around the double bond but aren't we supposed to have two similar groups on the other side as well ? Does this mean that we only ...
0
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1answer
262 views

E and Z configuration [closed]

In the above we need to find the configuration of the two double bonds whether (E) or (Z) according to me the one with the cyanides should be (E) and the other (E) however my book say that the correct ...
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2answers
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Confusion on syn and anti

I came across the following compound syn acetaldoxime However why is it syn because the lone pair having lowest priority is anti to H which is lowest priority on other side. Please clarify
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1answer
357 views

Geometrical Isomerism (Cis-Trans) in trans-2-fluoro-3-methylpent-2-ene

trans-2-fluoro-3-methylpent-2-ene this compound in also known as (Z)2-fluoro-3-methylpent-2-ene. I have given my possible structure in the image but it is wrong, Can anyone explain this ?
4
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1answer
243 views

What is the difference between a 500W high pressure mercury lamp and a 400W high pressure mercury lamp

I know that the Wattage of a UV lamp is only one factor in the UV output of a light, and therefore cannot be used as a measure of how powerful a light is. Also it doesnt have any effect on the ...
3
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1answer
111 views

How to choose a UV lamp for photoisomerization of 4,4'-azobenzene dicarboxylic acid?

I have prepared a thin film containing 4,4'-azobenzene dicarboxylic acid and I want to study the photoresponsive behaviour of them. For the trans-cis isomeration , I used a 365 nm UV LED with ...
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2answers
2k views

When is rotation around double bonds to form cis-trans isomers allowed?

The Rhodopsin molecules in the retain contain a derivative of vitamin A called cis-retinal (Figure 6). On exposure to light, cis-retinal becomes an isomer called trans-retinal (Textbook Question). ...
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0answers
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Number of geometrical isomers [duplicate]

How do I find out the total no of geometrical and stereo isomers of the compound given as $\ce{C2FClBrI}$? Is there any way I can list out all the possible structures mathematically without having to ...
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2answers
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Number of geometrical isomers when a cyclic ring is involved along with axis of symmetry

This is an question from my Chemistry study material and it asks to find the number of Geometrical Isomers of the following compound in the picture. Basically the method/formula given in my book to ...
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159 views

What type of isomers are the following two compounds?

What type of isomers are the following two compounds?They do not seem to be geometrical isomers as the methyl groups at terminal position are not in same plane as such.Are they conformers?
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2answers
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How to derive these general formulae for number of stereoisomers of a compound with a possible plane of symmetry?

These formulae are used if the molecule has a possible plane of symmetry. One such example would be: Here the carbons marked with an asterisk are stereogenic centres (the asterisk is not used to mark ...
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2answers
608 views

E/Z stereoisomers : assigning priorities with a cycloalkane group

For the following compound Right hand side of double bond: $\ce{CO2CH3}$ is highest priority due to the extra carbon (as we work along both chains) But for the left hand side oft he double bond I ...
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2answers
299 views

Optical Isomerism

I have been told that structurally symmetric molecules are optically inactive irrespective of the atoms that are being used. However I see optical activity as the force that turns plain polarised ...
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1answer
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Physical properties of geometric isomers

I've learnt that cis isomers have higher boiling point than the trans ones. Why does not that rule apply on Fumaric and maleic acids?
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331 views

Draw a structure for each of the following isomers of unsaturated amine 1

My ochem professor has several practice exams as resources but does not include answers, I believe I understand the concepts but once I apply them I'm not sure whether I'm right or clueless. Can ...