Concept explainers
Interpretation:
The structure of each alkene is to be drawn and classified on the basis of substitution on the double bond, the structure of product formed from each alkene on hydrogenation is to be written, the heat of hydrogenation can be used to relate the relative stabilities of
Concept introduction:
Hydrogenation of alkenes or
Stability of the isomers is inversely proportional to the steric hindrance. The more the steric hindrance, the lesser will be the stability of isomer.
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Chapter 7 Solutions
Organic Chemistry
- (c) You conducted an experiment involving a hydrohalogenation reaction with starting material A and HBr. Product C was obtained as the major product of the reaction instead of the regioisomer product B which you expected. CH3 CH3 CH3 Br Br + HBr Product B Starting material A Product C (i) Suggest a detailed reaction mechanism to explain the formation of the major product C. (ii) Briefly explain why this unexpected major product C predominated in your reaction. Question 1 Continued (iii) 1,2-elimination of HBr from product C yields a mixture of two alkenes. Draw the structures of the two alkene products and briefly explain using Zaitsev's rule which alkene is the major one.arrow_forward1)Chemistry students are taking an experimental course in organic chemistry at a public university. During an experiment involving conjugated dienes, some doubts arose when discussing the results obtained so far: (a) A student obtained two products from the reaction of 1,3-cyclohexadiene with Br2. His lab partner was surprised to get only one product from the reaction of 1,3 - cyclohexadiene with HBr. Explain these distinct results. (b) One student, seeing the discussion of colleagues, commented that she obtained two distinct products when reacting 1,3,5-hexatriene with HBr, with different yields just by changing the reaction temperature. Explain the results she obtained using reaction mechanism and based on kinetic and thermodynamic control involving conjugated dienes.arrow_forwardCompound X, C,4H12Br2, is optically inactive. On treatment with strong base, X gives hydrocarbon Y, C14H10: Compound Y absorbs 2 equivalents of hydrogen when reduced over a palladium catalyst to give z (C14H14) and reacts with ozone to give one product, benzoic acid (C,Hg02). Draw the structure of compound Z. • Use the wedge/hash bond tools to indicate stereochemistry where it exists. • Ignore alkene stereochemistry. • If more than one structure fits the description, draw them all. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. • Separate structures with + signs from the drop-down menu. ChemDoodlearrow_forward
- Carbon–carbon bond dissociation enthalpies have been measured for many alkanes. Identify the alkane in each of the following pairs that has the lower carbon–carbon bond-dissociation enthalpy, and explain the reason for your choice. (a) Ethane or propane (b) Propane or 2-methylpropane (c) 2-Methylpropane or 2,2-dimethylpropane (d) Cyclobutane or cyclopentanearrow_forwardGive reasons: (i) C—Cl bond length in chlorobenzene is shorter than C—Cl bond length in CH3—Cl.(ii) The dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.(iii) SN1 reactions are accompanied by racemization in optically active alkyl halidesarrow_forwardAssign E or Z stereochemistry to each of the following alkenes, and convert each drawing into a skeletal structure (red = 0, yellow-green = Cl). (a) (b)arrow_forward
- 2. (a) The heat of combustion of liquid benzaldehyde (C6H5CHO) is -3393 kJ/mole, and that of liquid 2,4,6-cycloheptatrien-1-one (C₂H6O) is -3470 kJ/mole. Assume that both combustions result in products, CO2 and H₂O, that are entirely in the gas phase. Using the standard chemical equation for the combustion of a hydrocarbon, find the heats of formation (in kJ/mol) for both benzaldehyde and 2,4,6-cycloheptatrien-1-one in the liquid phase. (b) Consider the isomerization from 2,4,6-cycloheptatrien-1-one to benzaldehyde. What is the enthalpy change (in kJ/mol) for this reaction? Is it endothermic or exothermic? (c) If ArxnS = -18 J/mol-K for the isomerization reaction, find ArxnG at 350 K (in kJ/mol) and determine if it is spontaneous in the liquid phase at this temperature. For this calculation, you may assume that ArxnH and ArxnS are constant between 300 and 350 K.arrow_forward(a) How will you carry out the following conversions?(i) Acetylene to Acetic acid (ii) Toluene to m-nitrobenzoic acid(iii) Ethanol to Acetone(b) Give reasons :(i) Chloroacetic acid is stronger than acetic acid.(ii) pH of reaction should be carefully controlled while preparing ammonia derivatives of carbonyl compounds.arrow_forwardConsider the reaction between (1S,3S)‑1‑chloro‑3‑methylcyclopentane and methanethiol in the presence of sodium hydroxide. (a) Draw the organic product and clearly indicate stereochemistry by showing the hydrogen on the chirality centers and using wedge and dash bonds. (b) Then analyze the stereochemistry of the product. racemic chiral achiral (1R, 3S) (1R, 3R) (1S, 3S)arrow_forward
- 2.arrow_forward(c) A series of dialkyl ethers react with excess hydrogen bromide, with the following results. Analyze the ether in each case and write out the complete chemical equations. (1) Ether gives a mixture of bromocyclopentane and 1-bromoethane. (ii) Another ether gives one mole of 1,5-dibromopentane per mole of ether.arrow_forward(a) Cyclohexa-1,3-diene can be converted into a tetrasubstituted haloalkane when reacted with bromine in ether. Write a balanced chemical equation for the reaction that occurs and state the expected observation. (b) Compound A and B are alkenes with the same molecular formula C5H10. Compound A is a branched-chain alkene while compound B is a straight-chain alkene. The reaction between compound A with hydrogen bromide produces major product C which is optically active. (i) Draw TWO (2) possible structures for compound B. (ii) Outline the mechanism for the reaction between compound A with hydrogen bromide to form major product C. (iii) Name the product formed when compound A undergoes bromination reaction.arrow_forward