4. Acquisition

Time requirement: 0.5 h

Sample: 2-hydroxynaphthalene, saturated solution in CDCl₃.

Prior to this experiment the decoupler attenuation for a rectangular soft pulse must be known (see Exp 7.2). Record an ¹H NMR spectrum and note the offsets of the different proton signals. Switch the instrument to ¹³C operation, record as a reference a normal ¹³C NMR spectrum, and load the INAPT pulse program. You have to set:

decoupler attenuation and 90° pulse for CPD
td	32 k
sw	55 ppm
o1	center of aromatic region of the ¹³C NMR spectrum
o2	on resonance of selected ¹H NMR signal use here
p1, p3	20 ms rectangular shaped ¹H decoupler pulse at 67 dB attenuation (90°
p2, p4	40 ms rectangular shaped ¹H decoupler pulse at 67 dB attenuation 180°
p5, p7	180° ¹³C transmitter pulse
p6	90° ¹³C transmitter pulse
d1	3 s
d2	10 ms
d3	20 ms
ns	64

5. Processing

Use standard ¹³C NMR processing as described in Experiment 3.2.

6. Result

In the figure a is the normal ¹H NMR spectrum recorded on an AMX-500 spectrometer with the assignments obtained by inspection of a NOESY experiment. b is the normal ¹³C NMR spectrum. In c the selective proton pulse was adjusted to H-8, giving responses from carbon nuclei C-6, C-10 and C-1, all of which are connected to H-8 via ³J(C,H). Note that the sign of the signals may be positive or negative. In d proton H-1 was irradiated, giving responses from C-10, C-8, C-2 and C-3.