Construct the electron dot structure of acetamide

A simple procedure for writing Lewis dot structures was given in a previous post entitled “Lewis Structures and the Octet Rule”.

Several worked examples relevant to this procedure were given in previous posts please see the Sitemap - Table of Contents (Lewis Electron Dot Structures).

Let us consider the case of acetamide CH₃CONH₂

Acetamide has many uses and applications such as:

• As a general solvent (molten acetamide is excellent solvent for many organic and inorganic compounds)

•  in biocides

• in preparation of cosmetics and hypnotics, 

• in various organic and inorganic syntheses, 

• as a drug intermediate in the manufacture of ampicilline, cephaclor, cephalexin, cephradine, enalapril

• as an antacid in lacquers and cosmetics

• as a plasticiser in leather and coatings

Step 1: Connect the atoms with single bonds.

Fig. 1 : Connect the atoms of acetamide with single bonds.

Step 2: Calculate the # of electrons in π bonds (multiple bonds)  using  formula (1): 


 

Where n in this case is 4 since CH₃CONH₂  consists of nine atoms but five of them is H.

Where V = (1*3 + 4 + 4 + 6 + 5 + 1*2) = 24 

Therefore, P = 6n + 2 – V = 6 * 4 + 2 – 24 = 2       So there are 2 π electrons in CH₃CONH₂ and therefore1 double bond must be added to the structure of Step 1.

Step 3 & 4: One double bond must therefore be placed in the structure shown in Fig 1:

Figure 2: Lewis structures of acetamide