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(a)
Interpretation:
The specific relationship between the pair of molecules shown is to be determined.
Concept introduction:
The intersection of a horizontal and vertical line indicates a carbon atom- typically an asymmetric carbon. The atom at the intersection is a carbon atom. The substituents on the vertical bonds point away from the observer while those on the horizontal bonds point toward the observer.
To determine the R/S configuration at the asymmetric carbon (chiral center), the vertical bonds are replaced by dash bonds and horizontal ones by wedge bonds. The groups on these bonds are then assigned priorities according to Cahn-Ingold-Prelog rules. If the priority groups 1 to 3 are arranged clockwise with the lowest priority group pointing away (at the back), the configuration of the asymmetric carbon is R. If they are arranged counterclockwise, the configuration is S.
If the lowest priority group is pointing toward the observer (it is in the front), then the actual configuration is reverse of that indicated. That means if the arrangement is clockwise, the actual configuration is S, and if counterclockwise, it is R.
If the molecules have different formulas, they are unrelated compounds. If the formulas are same, but the connectivity of atoms is different, the molecules are constitutional isomers.
If the formulas as well as connectivities are the same, then the molecules may be the same or stereoisomers.
The configuration of each asymmetric carbon is then compared to determine the specific relationship between the two molecules. If the configurations are the same, the molecules may be the same or conformers of the same molecule. Conformers are molecules that can be interconverted by a rotation about a single bond.
If the configurations at a single chiral center are different, then the two molecules are enantiomers.
If the molecule contains more than one chiral center, then a difference in the configuration of all chiral centers makes them enantiomers. If the configurations are different at some but not all the chiral centers, then the molecules are diastereomers.
Answer to Problem 5.73P
The molecules are the same.
Explanation of Solution
The Fischer projections are
After converting the Fischer projections to dash-wedge representation, it can be shown that the two are the same.
Rotating the first molecule through
Therefore, the two molecules are the same.
The two molecules are identical because rotating the dash-wedge structures interconverts them into each other.
(b)
Interpretation:
The specific relationship between the pair of molecules shown is to be determined.
Concept introduction:
The intersection of a horizontal and vertical line indicates a carbon atom- typically an asymmetric carbon. The atom at the intersection is a carbon atom. The substituents on the vertical bonds point away from the observer while those on the horizontal bonds point toward the observer.
To determine the R/S configuration at the asymmetric carbon (chiral center), the vertical bonds are replaced by dash bonds and horizontal ones by wedge bonds. The groups on these bonds are then assigned priorities according to Cahn-Ingold-Prelog rules. If the priority groups 1 to 3 are arranged clockwise with the lowest priority group pointing away (at the back), the configuration of the asymmetric carbon is R. If they are arranged counterclockwise, the configuration is S.
If the lowest priority group is pointing toward the observer (it is in the front), then the actual configuration is reverse of that indicated. That means if the arrangement is clockwise, the actual configuration is S, and if counterclockwise, it is R.
If the molecules have different formulas, they are unrelated compounds. If the formulas are same, but the connectivity of atoms is different, the molecules are constitutional isomers. If the formulas as well as connectivities are the same, then the molecules may be the same or stereoisomers.
The configuration of each asymmetric carbon is then compared to determine the specific relationship between the two molecules. If the configurations are the same, the molecules may be the same or conformers of the same molecule. Conformers are molecules that can be interconverted by a rotation about a single bond.
If the configurations at a single chiral center are different, then the two molecules are enantiomers.
If the molecule contains more than one chiral center, then a difference in the configuration of all chiral centers makes them enantiomers. If the configurations are different at some but not all the chiral centers, then the molecules are diastereomers.
Answer to Problem 5.73P
The two molecules are the same.
Explanation of Solution
The Fischer projections are
The first projection is converted into the second one by a simple rotation through
Rotating a Fischer projection in the plane of the paper does not change the configuration.
(c)
Interpretation:
The specific relationship between the pair of molecules shown is to be determined.
Concept introduction:
The intersection of a horizontal and vertical line indicates a carbon atom- typically an asymmetric carbon. The atom at the intersection is a carbon atom. The substituents on the vertical bonds point away from the observer while those on the horizontal bonds point toward the observer.
To determine the R/S configuration at the asymmetric carbon (chiral center), the vertical bonds are replaced by dash bonds and horizontal ones by wedge bonds. The groups on these bonds are then assigned priorities according to Cahn-Ingold-Prelog rules. If the priority groups 1 to 3 are arranged clockwise with the lowest priority group pointing away (at the back), the configuration of the asymmetric carbon is R. If they are arranged counterclockwise, the configuration is S.
If the lowest priority group is pointing toward the observer (it is in the front), then the actual configuration is reverse of that indicated. That means if the arrangement is clockwise, the actual configuration is S, and if counterclockwise, it is R.
If the molecules have different formulas, they are unrelated compounds. If the formulas are same, but the connectivity of atoms is different, the molecules are constitutional isomers.
If the formulas as well as connectivities are the same, then the molecules may be the same or stereoisomers.
The configuration of each asymmetric carbon is then compared to determine the specific relationship between the two molecules. If the configurations are the same, the molecules may be the same or conformers of the same molecule. Conformers are molecules that can be interconverted by a rotation about a single bond.
If the configurations at a single chiral center are different, then the two molecules are enantiomers.
If the molecule contains more than one chiral center, then a difference in the configuration of all chiral centers makes them enantiomers. If the configurations are different at some but not all the chiral centers, then the molecules are diastereomers.
Answer to Problem 5.73P
The two molecules are enantiomers.
Explanation of Solution
The Fischer projections are
The projections are converted to sash-wedge representations as shown below. The four groups on the chiral carbon are then assigned priorities according to Cahn-Ingold-Prelog rules.
The priority 1 to 3 groups in the first molecule are arranged counterclockwise with the lowest priority H at the back. The configuration at this carbon is then S.
In the second molecule, these groups are arranged counterclockwise; therefore, its configuration is R, opposite that of the first molecule.
Therefore, the two molecules are enantiomers.
Molecules with a single chiral center are enantiomers if their configurations are different.
(d)
Interpretation:
The specific relationship between the pair of molecules shown is to be determined.
Concept introduction:
The intersection of a horizontal and vertical line indicates a carbon atom- typically an asymmetric carbon. The atom at the intersection is a carbon atom. The substituents on the vertical bonds point away from the observer while those on the horizontal bonds point toward the observer.
To determine the R/S configuration at the asymmetric carbon (chiral center), the vertical bonds are replaced by dash bonds and horizontal ones by wedge bonds. The groups on these bonds are then assigned priorities according to Cahn-Ingold-Prelog rules. If the priority groups 1 to 3 are arranged clockwise with the lowest priority group pointing away (at the back), the configuration of the asymmetric carbon is R. If they are arranged counterclockwise, the configuration is S.
If the lowest priority group is pointing toward the observer (it is in the front), then the actual configuration is reverse of that indicated. That means if the arrangement is clockwise, the actual configuration is S, and if counterclockwise, it is R.
If the molecules have different formulas, they are unrelated compounds. If the formulas are same, but the connectivity of atoms is different, the molecules are constitutional isomers.
If the formulas as well as connectivities are the same, then the molecules may be the same or stereoisomers.
The configuration of each asymmetric carbon is then compared to determine the specific relationship between the two molecules. If the configurations are the same, the molecules may be the same or conformers of the same molecule. Conformers are molecules that can be interconverted by a rotation about a single bond.
If the configurations at a single chiral center are different, then the two molecules are enantiomers.
If the molecule contains more than one chiral center, then a difference in the configuration of all chiral centers makes them enantiomers. If the configurations are different at some but not all the chiral centers, then the molecules are diastereomers.
Answer to Problem 5.73P
The two molecules are enantiomers.
Explanation of Solution
The Fischer projections of the molecules are
The molecules can be interconverted by exchanging the positions of two of the four groups,
Therefore these are enantiomer.
Exchanging positions of two of the four groups attached to an asymmetric carbon inverts its configuration.
(e)
Interpretation:
The specific relationship between the pair of molecules shown is to be determined.
Concept introduction:
The intersection of a horizontal and vertical line indicates a carbon atom- typically an asymmetric carbon. The atom at the intersection is a carbon atom. The substituents on the vertical bonds point away from the observer while those on the horizontal bonds point toward the observer.
To determine the R/S configuration at the asymmetric carbon (chiral center), the vertical bonds are replaced by dash bonds and horizontal ones by wedge bonds. The groups on these bonds are then assigned priorities according to Cahn-Ingold-Prelog rules. If the priority groups 1 to 3 are arranged clockwise with the lowest priority group pointing away (at the back), the configuration of the asymmetric carbon is R. If they are arranged counterclockwise, the configuration is S.
If the lowest priority group is pointing toward the observer (it is in the front), then the actual configuration is reverse of that indicated. That means if the arrangement is clockwise, the actual configuration is S, and if counterclockwise, it is R.
If the molecules have different formulas, they are unrelated compounds. If the formulas are same, but the connectivity of atoms is different, the molecules are constitutional isomers.
If the formulas as well as connectivities are the same, then the molecules may be the same or stereoisomers.
The configuration of each asymmetric carbon is then compared to determine the specific relationship between the two molecules. If the configurations are the same, the molecules may be the same or conformers of the same molecule. Conformers are molecules that can be interconverted by a rotation about a single bond.
If the configurations at a single chiral center are different, then the two molecules are enantiomers.
If the molecule contains more than one chiral center, then a difference in the configuration of all chiral centers makes them enantiomers. If the configurations are different at some but not all the chiral centers, then the molecules are diastereomers.
Answer to Problem 5.73P
The two molecules are enantiomers.
Explanation of Solution
The Fischer projections of the two molecules are
The molecules are aldonic acids with the same molecular formula and connectivity. Each contains three asymmetric carbons, C2, C3, and C4. Therefore, they can be the same molecules, conformers, or configurational isomers.
The two cannot be interconverted by a rotation about a single bond; therefore, they are not conformers.
The configurations of each of these three must be compared to determine the specific relation between the two molecules.
To determine the configurations of the three asymmetric carbons, the Fischer projection is redrawn as a dash-wedge structure at each carbon.
The vertical bonds in the Fischer projection are pointed away from the observer, while the horizontal ones are pointed toward the observer. The four groups attached to the asymmetric carbon are then assigned priorities according to Cahn-Ingold-Prelog rules. Based on the priorities, the configurations at the three asymmetric carbons in the first molecule are
Therefore, the two molecules are enantiomers.
When the configurations at every asymmetric carbon in the pair of molecules with the same formula and connectivity are different, the molecules are enantiomers.
(f)
Interpretation:
The specific relationship between the pair of molecules shown is to be determined.
Concept introduction:
The intersection of a horizontal and vertical line indicates a carbon atom- typically an asymmetric carbon. The atom at the intersection is a carbon atom. The substituents on the vertical bonds point away from the observer while those on the horizontal bonds point toward the observer.
To determine the R/S configuration at the asymmetric carbon (chiral center), the vertical bonds are replaced by dash bonds and horizontal ones by wedge bonds. The groups on these bonds are then assigned priorities according to Cahn-Ingold-Prelog rules. If the priority groups 1 to 3 are arranged clockwise with the lowest priority group pointing away (at the back), the configuration of the asymmetric carbon is R. If they are arranged counterclockwise, the configuration is S.
If the lowest priority group is pointing toward the observer (it is in the front), then the actual configuration is reverse of that indicated. That means if the arrangement is clockwise, the actual configuration is S, and if counterclockwise, it is R.
If the molecules have different formulas, they are unrelated compounds. If the formulas are same, but the connectivity of atoms is different, the molecules are constitutional isomers.
If the formulas as well as connectivities are the same, then the molecules may be the same or stereoisomers.
The configuration of each asymmetric carbon is then compared to determine the specific relationship between the two molecules. If the configurations are the same, the molecules may be the same or conformers of the same molecule. Conformers are molecules that can be interconverted by a rotation about a single bond.
If the configurations at a single chiral center are different, then the two molecules are enantiomers.
If the molecule contains more than one chiral center, then a difference in the configuration of all chiral centers makes them enantiomers. If the configurations are different at some but not all the chiral centers, then the molecules are diastereomers.
Answer to Problem 5.73P
The molecules are diastereomers.
Explanation of Solution
The Fischer projections of the two molecules are
The molecules are aldonic acids with the same molecular formula and connectivity. Each contains three asymmetric carbons, C2, C3, and C4. Therefore, they can be the same molecules, conformers, or configurational isomers.
The two cannot be interconverted by a rotation about a single bond; therefore, they are not conformers.
The configurations of each of these three must be compared to determine the specific relation between the two molecules.
To determine the configurations of the three asymmetric carbons, the Fischer projection is redrawn as a dash-wedge structure at each carbon.
The vertical bonds in the Fischer projection are pointed away from the observer while the horizontal ones are pointed toward the observer. The four groups attached to the asymmetric carbon are then assigned priorities according to Cahn-Ingold-Prelog rules. Based on the priorities, the configurations at the three asymmetric carbons in the first molecule are
Therefore, the two molecules are diastereomers.
Two chiral molecules with multiple chiral centers that differ in configuration at some but not all chiral centers are diastereomers.
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Chapter 5 Solutions
EBK ORGANIC CHEMISTRY: PRINCIPLES AND M
- For each reaction below, decide if the first stable organic product that forms in solution will create a new CC bond, and check the appropriate box. Next, for each reaction to which you answered "Yes" to in the table, draw this product in the drawing area below. Note for advanced students: for this problem, don't worry if you think this product will continue to react under the current conditions - just focus on the first stable product you expect to form in solution. དྲ。 ✗MgBr ? O CI Will the first product that forms in this reaction create a new C-C bond? Yes No • ? Will the first product that forms in this reaction create a new CC bond? Yes No × : ☐ Xarrow_forwardPredict the major products of this organic reaction: OH NaBH4 H ? CH3OH Note: be sure you use dash and wedge bonds when necessary, for example to distinguish between major products with different stereochemistry. Click and drag to start drawing a structure. ☐ : Sarrow_forwardPredict the major products of this organic reaction: 1. LIAIHA 2. H₂O ? Note: be sure you use dash and wedge bonds when necessary, for example to distinguish between major products with different stereochemistry. Click and drag to start drawing a structure. X : ☐arrow_forward
- For each reaction below, decide if the first stable organic product that forms in solution will create a new C - C bond, and check the appropriate box. Next, for each reaction to which you answered "Yes" to in the table, draw this product in the drawing area below. Note for advanced students: for this problem, don't worry if you think this product will continue to react under the current conditions - just focus on the first stable product you expect to form in solution. NH2 tu ? ? OH Will the first product that forms in this reaction create a new CC bond? Yes No Will the first product that forms in this reaction create a new CC bond? Yes No C $ ©arrow_forwardAs the lead product manager at OrganometALEKS Industries, you are trying to decide if the following reaction will make a molecule with a new C-C bond as its major product: 1. MgCl ? 2. H₂O* If this reaction will work, draw the major organic product or products you would expect in the drawing area below. If there's more than one major product, you can draw them in any arrangement you like. Be sure you use wedge and dash bonds if necessary, for example to distinguish between major products with different stereochemistry. If the major products of this reaction won't have a new CC bond, just check the box under the drawing area and leave it blank. Click and drag to start drawing a structure. This reaction will not make a product with a new CC bond. G marrow_forwardIncluding activity coefficients, find [Hg22+] in saturated Hg2Br2 in 0.00100 M NH4 Ksp Hg2Br2 = 5.6×10-23.arrow_forward
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- 3-Oxo-butanenitrile and (E)-2-butenal are mixed with sodium ethoxide in ethanol. Draw and name the structures of the products.arrow_forwardWhat is the reason of the following(use equations if possible) a.) In MO preperation through diazotization: Addition of sodium nitrite in acidfied solution in order to form diazonium salt b.) in MO experiment: addition of sodium hydroxide solution in the last step to isolate the product MO. What is the color of MO at low pH c.) In MO experiment: addition of sodium hydroxide solution in the last step to isolate the product MO. What is the color of MO at pH 4.5 d.) Avoiding not cooling down the reaction mixture when preparing the diazonium salt e.) Cbvcarrow_forwardA 0.552-g sample of an unknown acid was dissolved in water to a total volume of 20.0 mL. This sample was titrated with 0.1103 M KOH. The equivalence point occurred at 29.42 mL base added. The pH of the solution at 10.0 mL base added was 3.72. Determine the molar mass of the acid. Determine the Ka of the acid.arrow_forward
Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning