Constitutional Isomers vs. Stereoisomers Practice Problems

Identify the relationship between the compounds in each of the given pairs. Choose whether they are the same compounds, constitutional isomers, or not isomers.

a. BrCH=CHCH₂CH₃ and CH₂=CHCH₂CH₂Br
b. CH₃CH₂CH₂CH₂CH₃ and (CH₃)₄C

Identify if the given pair of molecules are constitutional isomers, stereoisomers, or identical.

Determine if the two molecules below are stereoisomers, constitutional isomers, or identical.

Specify whether the following pairs of structures depict constitutional isomers, stereoisomers, conformers, or different compounds.

Classify the relationship between the pairs of structures given below as the same compound, constitutional isomers, cis-trans isomers, or different compounds.

Determine the relationship between the pairs of structures given below as the same compound, constitutional isomers, cis-trans isomers, or different compounds.

Consider the following pairs of structures:

Identify the relationship between these pairs of structures as the same compound, constitutional isomers, cis-trans isomers, or different compounds.

Predict if the two molecules below are stereoisomers, constitutional isomers, or identical.

Determine the number of stereoisomers possible for the alkene shown below.

Identify the number of stereoisomers possible for the molecule shown below.

Determine if the two molecules below are stereoisomers, constitutional isomers, or identical.

If (CH₃)₂CBr₂ is planar, the molecule will have two stereoisomers as shown below. However, the shape around the carbon atom is tetrahedral. Draw a model of this compound.

Does (CH₃)₂CBr₂ have any stereoisomers? Explain your answer.

Identify the compounds which can be resolved into a pair of enantiomers.

a. 2,2-diethylaziridine

b. 1-methylpiperidin-1-ium chloride

Draw the three-dimensional structures of the following compounds. Draw the mirror image of each structure and label them as chiral or achiral. Also, label the pair representing enantiomers.

a. trans-1,2-dibromocyclopentane
b. cis-1,2-dibromocyclopentane

Determine the following for the given molecule:

I. Number of stereocenters

II. All possible stereoisomers

III. List of pairs of enantiomers and diastereomers

Identify the compounds which can be resolved into a pair of enantiomers.

a. N-methylaniline

b. 2-ethylpyrrolidine

c. 1-ethylpyrrolidine

Mark the stereocenters in the structure and sketch all the possible stereoisomers.

Identify the stereocenters in the structure and sketch all the possible stereoisomers.

Consider the molecule shown below:

Indicate all the stereocenters in the molecule and provide all its possible stereoisomers.

(i) Write a three-dimensional structure for bromocyclohexane and cis-1,2-dibromocyclobutane. Star all asymmetric carbons in the structure you draw.

(ii) Draw the mirror image for each three-dimensional structure, and state whether the mirror images and the structures you drew in part (i) are enantiomers or identical molecules.

Determine the relationship between the two compounds in each of the following pairs of compounds. Use models if necessary.
(i) (2R,3S)-2,3-dichlorohexane and (2S,3R)-2,3-dichlorohexane; (ii) (2R,3S)-dichlorohexane and (2R,3R)-dichlorohexane.

The following are two different cis isomers for the compound 1−methyl−3−isopropylcycloheptane.

Determine the relationship between these cis isomers.

(i) Predict the identity of products obtained in the reaction between fructose and HCN. (ii) Are these products enantiomers or diastereomers? How can you separate them? (iii) Are the products optically active? Explain your answer.

The figure below shows a cis isomer and a trans isomer for compound 1−methyl−2−isopropylcyclobutane.

Identify the relationship between a cis isomer and a trans isomer.

Find the total number of stereoisomers of the following alkene.

Draw three stereoisomers for cyclohepta-1,4-diene. Although cyclohepta-1,4-diene should have four stereoisomers, it only has three stereoisomers. Explain why is it so.

Determine the relationship between the two compounds in each of the following pairs of compounds. Use models if necessary.

Is it possible to separate the following pair of compounds by distillation or recrystallization? Explain.

How many compounds would there be of an alkyne with a molecular formula C₆H₁₀, including stereoisomers?

Provide the enantiomer of the indicated configuration in the structure.

For each of the following, draw all possible stereoisomers. Highlight compounds that have no stereoisomers.

a. 1,2-dibromocyclobutane

b. 4-amino-pentan-2-ol

Identify the pair of enantiomers from the following nine stereoisomers.

Draw all the possible stereoisomers for the compound given below.

2-chlorocyclopentan-1-amine

Determine the number of stereoisomers possible for the given substituted alkene.

For (2R,3S)-2,3-dichlorohexane and (1R,2R)-1,2-dichlorocyclohexane:

(1) Write the corresponding three-dimensional structures.

(2) Mark each chiral center in both molecules with a star (*).

(3) Show any planes of symmetry.

(4) draw any enantiomer.

(5) draw any diastereomers.

(6) classify each structure as achiral or chiral.

Natural products are organic molecules generated by living organisms. Docetaxel, an example of these compounds, is used in treating cancer. It is isolated from the European yew tree needles. Using its structure below, predict how many stereoisomers are possible for docetaxel.

Provide the enantiomer for the chiral molecule shown below using the following methods: (i) draw the non-superimposable mirror image of the molecule and (ii) swap the spatial orientation of the groups at each chiral center. Are the structures obtained from (i) and (ii) identical?

(i) Write a three-dimensional structure for leucine and 1-chloro-2-methylbutane. Star all asymmetric carbons in the structure you draw.

(ii) Draw the mirror image for each three-dimensional structure, and state whether the mirror images and the structures you drew in part (i) are enantiomers or identical molecules.

When pure (R)-3,4-dimethylpent-1-yne is reacted with hydrogen over a platinum catalyst, (S)-2,3-dimethylpentane is obtained as the product of the reaction.
(i) What is the relationship between the (R) or (S) designation with the sign of an optical rotation?
(ii) Is it possible to predict the sign of the rotation of the reactant or product based on information of (R) or (S) designation alone?

To show that the following two compounds are not enantiomers, write the structures of the mirror images of each compound and name them appropriately.
(2S,3S)-dibromopentane and (2S,3R)-dibromopentane.

Find the number of all possible stereoisomers of the following tetracyclic molecule.

Draw the nine stereoisomers of 1,2,3,4,5,6-hexabromocyclohexane. Use wedges and dashes in your drawings.

For each stereocenter in the following structures:

(i) Draw the structure you get when you interchange two of the groups on the stereocenter. 

(ii) Identify the relationship between the original compound and the new compound.

Shown in the figure below is the chemical structure of a derivative of Bryostatin 1. (i): How many chiral centers are in this molecule? (ii): Using the number of chiral centers from part (i), calculate the number of possible stereoisomers at these chiral centers. (Ignore stereoisomers at double bonds)

Illustrate the enantiomer for the given structure below:

Determine the number of stereoisomers possible for (a) 4-ethyl-7-methylnona-2,6-diene and (b) 6-bromo-8-methylnona-2,4,7-triene.

Draw the structures of all the stereoisomers possible for the compounds given below.

a. 2,3-dibromobutane

b. 1,2-dibromocyclopentane

Please consider the chiral molecule shown below. 

(a) Draw the non-superimposable mirror image of the molecule to obtain its enantiomer. 

(b) Interchange the spatial orientation of the groups at each chiral center to obtain another enantiomer. 

(c) Compare the structures obtained in (a) and (b) to determine if they are identical.

Amphetamine is an FDA-approved drug used to treat attention-deficit hyperactivity disorder (ADHD).

a. How many stereoisomers does amphetamine have?

b. One of the stereoisomers of amphetamine is shown below. Assign the absolute configuration to its asymmetric carbon.

Determine the number of possible stereoisomers for the molecule below.

(i) Write a three-dimensional structure for 2-chloropentane and 3-chloropentane. Star all asymmetric carbons in the structure you draw. 

(ii) Draw the mirror image for each three-dimensional structure, and state whether the mirror images and the structures you drew in part (i) are enantiomers or identical molecules.

Draw all the stereoisomers of valine. Identify the enantiomers and diastereomers among them.

Is it possible to separate these compounds by distillation or recrystallization? Explain your answer.

Write the enantiomer for each of the following structures.

Provide the four pairs of diastereomers of 1-chloro-2-ethylcyclobutane.

Give all the possible stereoisomers of 5-fluoroheptan-3-ol.

Choose the structure that is a diastereomer for each of the molecules below:

Provide the four stereoisomers of 1,4-difluorohexan-2-amine.

Provide all the possible stereoisomers for the compounds given below.

(i) 1,3-dimethylcyclohexane

(ii) 1,4-dimethylcyclohexane

Provide all the possible stereoisomers for the compounds given below. If no stereoisomers are possible, write "none."

(i) 1-fluoro-4-methylcyclohexane

(ii) 1,2-dichlorocyclopropane

Consider the isomers of 1-bromo-2-chlorocyclobutane. Identify the relationship between the trans isomers.

Draw the structure of the following molecule with a three-dimensional depiction of the asymmetric carbon (carbon that has four different atoms/groups attached to it).

For the molecule given below, draw a structure with a three-dimensional depiction of the carbon that has four different atoms/groups attached to it.