443 - Practice Problem 4‐43 – Answer Draw structures...

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Unformatted text preview: Practice Problem 4‐43 – Answer Draw structures for the products of complete hydrolysis of meprobamate, phenobarbital, and pentobarbital in hot aqueous acid. Practice Problem 4‐44 – Answer Draw a structural formula of the principal product formed when benzonitrile is treated with each reagent (a) H2O (one equiv), H2SO4, heat (b) H2O (excess), H2SO4, heat (c) NaOH, H2O, heat Practice Problem 4‐45 – Answer Draw a structural formula of the principal product formed when benzoyl chloride is treated with each reagent (a) (CH3)2CuLi, then H3O+ (b) C6H5MgBr (two equiv), then HCl/H2O Practice Problem 4‐46 – Answer Show the product of treating γ‐butyrolactone with each reagent. Practice Problem 4‐47 – Answer Propose a sequence of reactions to convert the indicated starting material to the indicated target compound, using any other organic and/or inorganic reagents necessary. Synthesis: Practice Problem 4‐48 – Answer Show the product expected when the following unsaturated d‐ketoester is treated with each reagent. Practice Problem 4‐49 – Answer The following sequence of steps converts (R)‐2‐octanol to (S)‐2‐octanol. Propose structures for Compounds A and B. Show stereochemistry! Practice Problem 4‐50 – Answer The following statements are true experimental observations. Explain the reason behind each observation. (a) The reaction of acetic acid with NH3 in water does not yield any amide products. Acetic acid is acidic, and ammonia is a base. They react in a proton transfer reaction to produced the acetate anion and the ammonium cation. This reaction is significantly faster than any potential nucleophilic acyl substitution reaction would be! (b) The reaction of acetyl chloride with water causes the pH to decrease. As an acid chloride is hydrolyzed, acetic acid and hydronium are produced as products. Formation of these acidic products causes the pH of the solution to drop. See the mechanism for acid chloride hydrolysis that we discussed in lecture on Tuesday, August 3. (c) The hydrolysis of an amide at neutral pH takes seven years at room temperature, while the hydrolysis of an acid chloride only takes a few minutes. Since it is a weaker base, the chloride anion is a better leaving group than the amide anion. Also, the amide carbonyl carbon atom is less reactive toward nucleophiles since it is surrounded by more electron density. Both of these factors were discussed in detail during lecture on Tuesday, August 3. Practice Problem 4‐51 – Answer Using the principles for writing reaction mechanisms that we have discussed during lecture, write mechanisms showing all electron flow arrows for the following reactions: (a) Hydrolysis of N,N‐dimethylacetamide in acidic water. (b) Hydrolysis of acetic anhydride in basic water. (c) Esterification of acetic acid in acidic ethanol. (d) The reaction of dimethylamine in water with acetic anhydride to create N,N‐dimethylacetamide. (e) Partial hydrolysis of acetonitrile in acidic water to create acetamide. Practice Problem 4‐52 – Answer Show how to convert phenylacetylene to allyl phenylacetate. Synthesis: Practice Problem 4‐53 (1st one) – Answer Show how to synthesize 5‐nonanone from 1‐bromobutane as the only organic starting material. Retrosynthetic analysis: Synthesis: Practice Problem 4‐53 (2nd one) – Answer Show how to convert (E)‐3‐hexene into propyl propionate. You must use (E)‐3‐hexene as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way. Synthesis: Practice Problem 4‐54 – Answer Show how to convert 1‐bromopropane and sodium cyanide into N‐hexylhexanamide. You must use 1‐ bromopentane and sodium cyanide as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way. Retrosynthetic analysis: Synthesis: Practice Problem 4‐55 – Answer Show how to convert 1‐bromopropane and carbon dioxide into 4‐propyl‐4‐heptanol. You must use 1‐ bromopropane and carbon dioxide as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way. Retrosynthetic analysis: Synthesis: Practice Problem 4‐56 – Answer Show how to convert 1‐bromopropane and carbon dioxide into 4‐heptanone. You must use 1‐bromopropane and carbon dioxide as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way. Retrosynthetic analysis: Synthesis: ...
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