Question

Draw structural formulas for the products of complete hydrolysis of meprobamate, phenobarbital, and pentobarbital in hot aqueous acid. (a) CCCC(C)(COC(N)=O)COC(N)=O (b) CC1(c2ccccc2)C(=O)NC(=O)NC1=O (c) CCCC(C)C1(CC)C(=O)NC(=O)NC1=O Meprobamate (racemic) \(\begin{array}{cc}\begin{array}{c}\text { Phenobarbital } \\ \text { (racemic) }\end{array} & \text { Pentobarbital } \\ \text { (racemic) }\end{array}\) Meprobamate is a tranquilizer prescribed under 58 different trade names, including Equanil and Miltown. Phenobarbital is a long-acting sedative, hypnotic, and anticonvulsant. Luminal is one of over a dozen names under which it is prescribed. Pentobarbital is a short-acting sedative, hypnotic, and anticonvulsant. Nembutal is one of several trade names under which it is prescribed.

Short answer

In this exercise, we have drawn the structural formulas for the products of complete hydrolysis of three compounds - meprobamate, phenobarbital, and pentobarbital in hot aqueous acid. After identifying the functional groups that undergo hydrolysis (carbamates and amides) and drawing the structural formulas of the given compounds, we hydrolyzed carbamates and amides to their corresponding products. The final hydrolyzed products are: (a) Isobutanol and 2 equivalents of ammonia (NH3) for meprobamate. (b) 5-ethyl-5-phenyl-1,3-dioxane-4,6-dione and 2 equivalents of ammonia (NH3) for phenobarbital. (c) 5-ethyl-5-pentyl-1,3-dioxane-4,6-dione and 2 equivalents of ammonia (NH3) for pentobarbital.

Step-by-step solution

Meprobamate, phenobarbital, and pentobarbital contain carbamate and/or amide moieties. Carbamates and amides will undergo hydrolysis under acidic conditions. In the case of these compounds, it is essential to identify carbonyl groups containing the nitrogen atom, such as -CON-R and -CO-NR2. ##Step 2: Draw the structural formulas of the given compounds##

Here are the structural formulas of the compounds: Meprobamate: CCCC(C)(COC(N)=O)COC(N)=O Phenobarbital: CC1(c2ccccc2)C(=O)NC(=O)NC1=O Pentobarbital: CCCC(C)C1(CC)C(=O)NC(=O)NC1=O ##Step 3: Perform the hydrolysis of carbamates and amides##

In hot aqueous acid, carbamates (-CON-R) will hydrolyze into an alcohol (ROH) and a primary amine (H2NR). Amides (-CO-NR2) will hydrolyze into a carboxylic acid (RC(=O)OH) and a primary amine (H2NR). For each molecule, identify the carbamates and/or amides and their products after hydrolysis. (a) Meprobamate: Two carbamate moieties are present: - Hydrolyze both -CONH2 groups to form isobutanol and two equivalents of ammonia (NH3): Meprobamate + 2 H2O -> isobutanol + 2 NH3 (b) Phenobarbital: Two amide moieties are present: - Hydrolyze both -CONH2 groups to form 5-ethyl-5-phenyl-1,3-dioxane-4,6-dione and two equivalents of ammonia (NH3): Phenobarbital + 2 H2O -> 5-ethyl-5-phenyl-1,3-dioxane-4,6-dione + 2 NH3 (c) Pentobarbital: Similar to phenobarbital, there are two amide groups to hydrolyze: - Hydrolyze both -CONH2 groups to form 5-ethyl-5-pentyl-1,3-dioxane-4,6-dione and two equivalents of ammonia (NH3): Pentobarbital + 2 H2O -> 5-ethyl-5-pentyl-1,3-dioxane-4,6-dione + 2 NH3 ##Step 4: Draw the structural formulas of the hydrolyzed products##

Here are the structural formulas of the hydrolysed products: (a) Isobutanol: CCCC(C)(CO)O (b) 5-ethyl-5-phenyl-1,3-dioxane-4,6-dione: CC1(c2ccccc2)C(=O)OC(=O)OC1=O (c) 5-ethyl-5-pentyl-1,3-dioxane-4,6-dione: CCCC(C)C1(CC)C(=O)OC(=O)OC1=O