NaBH (OAc)3 R2-NH Figure 1. Reaction Scheme. Prelab Questions 1) The Material Sa
ID: 870714 • Letter: N
Question
NaBH (OAc)3 R2-NH Figure 1. Reaction Scheme. Prelab Questions 1) The Material Safety Data Sheets (MSDS) for some of the chemicals involved in this lab are on iLearn. Read the MSDS sheets for sodium triacetoxyborohydride and dichloromethane and explain the safety precautions you will take when handling these materials. 2) Read the special section (p34-46) and explain why protons attached to nitrogen (i.e. N-H) show broad peaks in the H NMR and do not couple to other protons. 3) If the reaction doesn't go to completion, you will have aldehyde starting material present. How would you identify this impurity most easily by 1H NMR? 4) How would you identify an aldehyde by IR spectroscopy?Explanation / Answer
2) In the 1H NMR spectrum of product, protons attached to nitrogen (N-H) will exhibit broad peaks is due to the intermolecular proton exchange (N-H) process. Due to the rapid proton exchange in NH system would not allow the proton to interact or to couple with the neighbouring other protons.
3) If the reaction doesnot go to completion, the presence of aldehyde can be identify easily by looking at the aldehydic proton peak in the range of 10- 9 ppm (Chemical shift value).
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