Question

Following is a retrosynthetic analysis for the acaracide (killing mites and ticks) and fungicide dinocap. (a) Given this analysis, propose a synthesis for dinocap from phenol and l-octene. (b) Is dinocap chiral? If so, which of the possible stereoisomers are formed in this synthesis?

Short answer

Question: Propose a synthesis for dinocap from phenol and l-octene, and determine if dinocap is chiral. Answer: The synthesis of dinocap can be achieved through the following steps: 1. Perform an electrophilic aromatic substitution (Friedel-Crafts alkylation) using l-octene and an acid catalyst on the phenol. 2. Add a nitration step to introduce a NO_2 group to the substituted phenol product(s) using concentrated nitric acid (HNO_3) and concentrated sulfuric acid (H_2SO_4). 3. Reduce the nitro group in the phenol to obtain the corresponding amine using methods such as catalytic hydrogenation (using H_2 gas and a catalyst like Pt, Pd, or Ni) or reducing agents like Sn/HCl, Zn/HCl, NaBH_4, or NH_2NH_2. Dinocap is not chiral, as it does not have any stereocenters in its molecular structure.

Step-by-step solution

Draw the structures of dinocap, phenol, and l-octene.

First, draw the structure of dinocap, phenol, and l-octene to better understand the molecules and the synthesis process. Dinocap: C_10H_19NO_2S Phenol: C_6H_6O l-octene: C_8H_16

Propose a synthesis for dinocap from phenol and l-octene.

The proposed synthesis is as follows: 1. Perform an electrophilic aromatic substitution (Friedel-Crafts alkylation) on the phenol by using l-octene and an acid catalyst (e.g., AlCl_3 or FeCl_3). The l-octene will act as the electrophile, and phenol’s oxygen will coordinate with the acid catalyst to direct the octyl group to ortho- or para- positions. This will give you an isomeric mixture of 2-octylphenol and 4-octylphenol products. 2. Next, perform a nitration on the substituted phenol product(s) from step 1 to add a NO_2 group to the substituent-free aromatic position. This can be achieved using a mixture of concentrated nitric acid (HNO_3) and concentrated sulfuric acid (H_2SO_4) at low temperatures. This will yield 4-(octyl)nitrophenol and/or 2-(octyl)nitrophenol. 3. Finally, perform a reduction of the nitro group in the phenol to obtain the corresponding amine. The nitro group can be reduced using several methods such as catalytic hydrogenation (using H_2 gas and a catalyst like Pt, Pd, or Ni), reducing agents like Sn/HCl, Zn/HCl, NaBH_4, or NH_2NH_2, etc. This reduction will yield the desired dinocap molecule.

Determine the chirality of dinocap.

To determine if dinocap is chiral, look for stereocenters (carbon atoms with four different attached groups) in the molecule. Since there are no stereocenters in the dinocap molecule, it is not chiral.

Identify possible stereoisomers if dinocap is chiral.

As determined in Step 3, dinocap is not chiral, so there are no possible stereoisomers to identify. The synthesis process will yield a single constitutional isomer.