M for ch 13 12 13c adjacentsar e smal l 001 99 of

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Unformatted text preview: to the sampl e (H / D exchange). 13 13 C NMR Spectroscopy 13 13 13 13 Onl y 1% 13C i n natur e: N o C— C Onl sFori tti ng, sirnce chances ofseen i n 1ngNtwo 13 ( pl the same eason: No 13C—H fi ndi H NM R. M (For C—H 13 12 13C adjacentsar e smal l (~0.01%). 99% of sampl e i 12C). But : 13C—H vi si bl e i n 13C NM R. 13 B ut 13C—H L ar ge J s CH J ~ 100-150 H z 100-150 J ~ 5-10 H z 5-10 CCH T r i pl et of quar tets quar Quar tet of Quar tr i pl ets tr Coupl i ng to H can be r emoved by “ br oad band” i r r adi ati on of al l Hs aver ages H α/ β H ence: all l l i nes ar e si ngl ets ! a Symmetry Symmetry C7H 14 i somer s Number of Cs: 5 5 4 4 3 1 7 Chemi cal shi ft r ange : 200 ppm (1H : 10 ppm) Chemi 200 Rul es for deshi el di ng same as i n 1H N M R Rul NM (mul ti pl y by a factor of 10-20) (mul Chemical Shift Range Advanced Techniques Advanced D i stor ti onl ess pol ar i zati on tr ansfer Di (“ DEPT ” ) 13C N M R spectr um. Tel l s us (“ ”) 13 NM w hether the car bon i s attached to 3, 2, 1 or no hydr ogen , i .e. CH , CH , CH , or C. no CH CH CH or Requi r es r unni ng the spectr um i n thr ee d i ffer ent ways (usi ng speci fi c l aser pul se sequences). sequences). E xampl e : L i monene. Exampl Nor mal spectr um N or DEPT-90 spectr um: onl y CH onl D EPT-135 spectr um: DEPT-135 3 CH and CH posi ti ve CH CH posi CH negati ve peaks n egati Two Dimensional NMR Two Cor r el ated spectr oscopy (COSY). ). H / H or H / C 10 200 H NM NM R 1 Coupl ed Coupl Hs C—H C—H connecti vi ty connecti 13 C 0 1 10 ppm 0 H 1 H 1 0 MRI : Magnetic Resonance Imaging Imaging B ased on “r el axati on” ti mes β Based T 1 val ues di ffer wi th ti ssue (envi r onment) (envi Whol e body NM R α, “ T 1” MRI of Human Abdomen MRI l i ver ki dneys spl een MRI, median sagittal section: cervicodorsal syringomyelia. This condition is characterized by the presence of fluid­filled cavities in the spinal cord substance. Brain Tumo...
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