(b) One of your illustrious colleagues continues his/her education and finally obtains employment with a renowned pharmaceutical company as an organic chemist. He or she is asked to synthesize pantothenic acid because the company wants to use it to prepare a synthetic form of coenenzyme A. Your colleague devises a seven-step synthesis for pantothenic acid:

(1) Isobutyraldehye + formaldehyde + NaOH/H2O → II (C5H10O2)
(2) II + NaCN → (C6H10O2 NNa) + H2O → III (C6H11O2 N) + NaOH
(3) III + H2O + H2SO4 + heat → IV (C6H12O4) + NH4HSO4
(4) IV + H3O+ + heat → V (C6H10O3)
(5) V + NaOH + heat → VI (C6H11O4Na)
(6) VI + sodium 2-aminopropionate → sodium pantothenoate + H2O
(7) Sodium pantothenoate + HCl(aq) → pantothenic acid + NaCl(aq)

(a) Suggest structures for II, III, IV, V, and VI.

Come on have a go at some of these steps and we will comment. I have done step 1 in a previous post.

To suggest structures for II, III, IV, V, and VI, we need to examine the reactions and products from the given synthesis steps.

Let's review the reactions and their products:

(1) Isobutyraldehyde + formaldehyde + NaOH/H2O → II (C5H10O2)
In this step, Isobutyraldehyde and formaldehyde react in the presence of NaOH and water. The resulting compound is denoted as II with the chemical formula C5H10O2.

(2) II + NaCN → (C6H10O2 NNa) + H2O → III (C6H11O2 N) + NaOH
In this step, II reacts with NaCN, resulting in the formation of a compound denoted as III. It comprises C6H11O2N.

(3) III + H2O + H2SO4 + heat → IV (C6H12O4) + NH4HSO4
Here, III undergoes a reaction with water, H2SO4, and heat. This leads to the formation of compound IV, denoted as C6H12O4. Another product of this reaction is NH4HSO4.

(4) IV + H3O+ + heat → V (C6H10O3)
In this step, IV reacts with H3O+ under heat, resulting in the formation of compound V. It has the chemical formula C6H10O3.

(5) V + NaOH + heat → VI (C6H11O4Na)
Here, V reacts with NaOH under heat, forming a compound denoted as VI. It comprises C6H11O4Na.

Now, let's summarize the structures for each compound:

II: C5H10O2
III: C6H11O2N
IV: C6H12O4
V: C6H10O3
VI: C6H11O4Na