NOE enhancement observed C NMR 13 Coupling is reduced, but multiplicity is retained; 1H irradiation 1 ppm upfield from TMS; to observe multiplicity at C-3, 1H irradiation could be set to 10 ppm downfield from
signals can be integrated Demonstration of the effect of NOE on decoupling C-9 signal as a function of H decoupling
C-9 3. Attached protons 4. Identification of nearest neighbors HH Identification of 1,1-Me Identification of 5-Me
Identification of H4 Identification of 10-Me Identification of H3 Identification of H2 p=3
q=2 Selective Decoupling irradiate H4 doublet
triplet little interaction normal spectrum Results are often reported as difference spectra 10
Note: peak s 2 and 3 are mislabeled Measurement of CH coupling constants Heteronuclear J resolved Spectrum Identify the carbons by chemical shift
i j h d f
e ab g c Let test our assignments using ACD
An INADEQUATE spectrum (incredible natural abundance double quantum transfer experiment spectroscopy) measures 13C 13C transfer of magnetization
between two 13 C nuclei using natural abundance C (detection of 1 in 10000 molecules). j i
j h i i h
f g e d f g
d c f e a,b a,b
AX3 XAM2 where JAX= JAM JXM = 0 Can we assign the peaks?
carbon count 2 =CC2 =CH 1 3 CH3
2 CH2 8,9,10 1 4,5 2,6 NOE Difference Spectra
Some NOE operates through space as well as through bonding electrons. The through space interaction decreases as the inverse of the sixth power of the through space distance of the nuclei. The through space interaction occurs between nuclei that interact by a dipolar interaction The NOE difference spectrum is obtained by subtracting a normal spectrum from one in which a specific proton is irradiated. An
measurable interaction can be expected up to about 4. 9 b a bb
Present Progressive: Irregular Forms Some verbs have irregular present participle forms. To form the present participle of -ir stem-changing verbs, the e in the infinitive form changes to i, and the o in the infinitive form changes to u.
Making Inferences Inference A reasonable guess about meaning. Reading "between the lines" to discover the author's meaning. What I learned (read) + What I already know = My inference In other words, an inference is an "educated guess". What you...
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Such a laser could potentially be used as a pump laser for an OPO (which would then itself need to be space-qualified). However, it would be nice to have a laser that is closer to CW rather than pulsed, as...
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Kesimpulan dari premis-premis di atas adalah .... Jika tidak terjadi banjir maka hujan tiba. Jika banyak warga terserang penyakit maka terjadi banjir. Jika musin hujan tiba maka banyak warga terserang penyakit. Jika banyak warga terserang penyakit maka musim hujan tiba.
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