Question

For my project I needed to di-substitute benzamide with ethyl group at N position to create DEB as a mosquito repellent. The first part of creating benzamide I was able to do, but the second part of substituting is a bit hard for me. I wanted to substitute using ethyl iodide as it was not a gas while the bromide and chloride was a gas.

Our lab apparently did not have the orthophosphoric acid to create hydroiodic acid in situ, so I resorted to using chloroethane, but I wasn't able to do it due to complications in my bubbling setup. Then I thought I could prepare orthophosphoric acid from sodium dihydrogen phosphate as it is available in our lab. Can someone help me on doing it, or is there any other method to do it without the above methods?
The available materials are ethanol, KI, NaH2PO4, HCl, HNO3, H2SO4, and there is no hydroiodic acid.

Answer 1

To substitute benzamide with an ethyl group at the N position, you can prepare orthophosphoric acid from sodium dihydrogen phosphate using hydrochloric acid and potassium iodide. Alternatively, you can use ethanol and react it with ethyl iodide.

Step-by-step explanation:

To perform the substitution of the benzamide with an ethyl group at the N position, you can prepare orthophosphoric acid from sodium dihydrogen phosphate, which is available in your lab. Here's the method:

1. Mix sodium dihydrogen phosphate (NaH₂PO₄) with hydrochloric acid (HCl) to form phosphoric acid (H₃PO₄).
2. React the phosphoric acid with potassium iodide (KI) to form orthophosphoric acid (H₃PO₄) and potassium chloride (KCl).

Alternatively, if you have access to ethanol, you can use it as a solvent and react it with ethyl iodide to directly substitute the benzamide with an ethyl group.