Compare the proton NMR spectra between the starting material biphenyl, and the product 4-acetylbiphenyl. (a) What does the peak at 2.58 ppm in the products ¹H-NMR spectrum represent? (b) Briefly describe

the difference in the aromatic region between the starting material and product. How many hydrogen atoms should be integrated for in the spectrum of biphonyl? (Consull Chapter 14 - NMR Spectroscopy of Bruice 8th Ed. and discuss these questions with your Pod Instructor for guidance. Table 14.1 on p. 629 is pasted below for your reference.) Table 14.1 Type of proton ppm -CH3 -CH₂- -CH- -c-c-c Approximate Values of Chemical Shifts (ppm) for ¹H NMR* Type of proton 요 -C-CH3 0.85 1.20 1.55 -CH3 1.7 2.1 -CH3 C=C II R-O-CH3 R-C=CH₂ R R-C-C-H RR ppm 2.3 2.4 3.3 4.7 5.3 *The values are approximate because they are affected by neighboring substituents. Type of proton I-C-H Br-C-H CI-C-H F- -H R-NH₂ ppm 2.5-4 2.5-4 3-4 4-4.5 Variable, 1.5-4 Type of proton R-OH -H ه OII -C-H __i -Ċ-OH C−NH, ppm Variable, 2-5 Variable, 4 7 6.5-8 9.0-10 Variable, 10-12 Variable, 5-8