Qhov sib txawv tseem ceeb ntawm kev hloov tshuaj lom neeg thiab kev sib txuas tsis tu ncua yog cov tshuaj hloov pauv piav qhia txog kev hloov pauv ntawm txoj haujlwm ntawm NMR nqus dej uas tshwm sim vim kev tiv thaiv los yog deshielding ntawm cov protons los ntawm cov electrons ntawm cov compound whereas coupling tas li hais txog kev sib cuam tshuam. nruab nrab ntawm ib khub ntawm protons.
Ob qho tshuaj hloov pauv thiab sib txuas tas li yog cov ntsiab lus uas muab cov lej muaj feem cuam tshuam nrog NMR. NMR yog nuclear magnetic resonance. Nws yog ib qho txheej txheem uas ua rau muaj cov teeb liab tshwm sim thaum muab cov qauv hauv qhov chaw sib nqus.
Kev hloov tshuaj lom neeg yog dab tsi?
Tshuaj hloov pauv yog qhov hloov pauv ntawm cov hlau nplaum sib nqus resonance zaus ntawm lub nucleus nyob ntawm qhov chaw hluav taws xob. Peb tuaj yeem txhais lo lus no ua δ. Kev hloov tshuaj lom neeg piav qhia txog kev hloov ntawm txoj haujlwm ntawm NMR nqus dej uas tshwm sim vim kev tiv thaiv los yog deshielding ntawm cov protons los ntawm cov electrons ntawm lub compound. Peb tuaj yeem txiav txim siab txog kev hloov tshuaj lom neeg los ntawm kev soj ntsuam qhov sib txawv ntawm txoj haujlwm nqus ntawm cov qauv proton thiab cov khoom siv proton ntawm cov qauv sib xyaw. Kev hloov tshuaj lom neeg muaj tus nqi uas peb tuaj yeem qhia los ntawm chav tsev ppm lossis qhov chaw ib lab. Muaj qee qhov tseem ceeb uas peb yuav tsum tau xav txog thaum xaiv tus qauv tsim nyog;
- Yuav tsum muaj tshuaj lom neeg
- Sib nqus isotropy
- Yuav tsum muab lub ncov uas yooj yim lees paub
- Nws yuav tsum muaj miscible nrog ntau cov kuab tshuaj
- Nws yuav tsum muab ib qho, ntse ncov
Tsis tas li ntawd, muaj qee yam cuam tshuam rau kev hloov tshuaj lom neeg; Piv txwv li, inductive effect, van der Waals deshielding, anisotropic effect thiab hydrogen bonding peev xwm ntawm cov compound.
- Thaum xav txog cov nyhuv inductive, siab dua cov electronegativity, siab dua cov nyhuv deshielding thiab siab dua cov tshuaj hloov nqi
- Nyob rau hauv Van der Waals deshielding nyhuv, muaj cov pab pawg loj ua rau lub repulsion ntawm cov huab electron nyob ib ncig ntawm pawg loj thiab protons, uas ua rau cov protons deshielded.
- Nyob rau hauv cov nyhuv anisotropic, muaj alkenes ua rau muaj tshuaj lom neeg ua haujlwm siab thiab muaj cov alkynes ua rau muaj tshuaj lom neeg tsawg.
- Cov nyhuv deshielding nyob ntawm lub zog ntawm hydrogen bonding.
Coupling Constant yog dab tsi?
Coupling tas li yog hais txog kev sib txuas ntawm ob kab uas nyob ib sab hauv NMR peaks ntawm ob pawg ntawm qhov sib npaug hydrogen nuclei. Peb tuaj yeem txheeb xyuas lo lus no raws li J. Qhov kev sib txuas tsis tu ncua ntsuas cov txiaj ntsig no tus lej, thiab chav ntsuas kev sib txuas tsis tu ncua yog Hertz lossis Hz. Nws yog ib qho kev ntsuas ntawm kev sib cuam tshuam ntawm ib khub ntawm protons.
Muaj peb hom kev sib txuas ua ke xws li cov kab mob sib txuas, cov kab sib txuas thiab cov kab txuas ntev ntev.
Dab tsi yog qhov txawv ntawm Kev Hloov Tshuaj thiab Coupling Constant?
Ob qho tshuaj hloov pauv thiab sib txuas tas li yog cov ntsiab lus uas muab cov lej muaj feem cuam tshuam nrog NMR. Kev hloov tshuaj lom neeg yog qhov kev hloov pauv hauv qhov sib nqus sib nqus resonance zaus ntawm lub nucleus nyob ntawm qhov chaw hluav taws xob. Coupling tas li hais txog kev sib txuas ntawm ob kab uas nyob ib sab hauv NMR peaks ntawm ob pawg ntawm qhov sib npaug hydrogen nuclei. Qhov sib txawv tseem ceeb ntawm kev hloov tshuaj lom neeg thiab kev sib txuas tsis tu ncua yog tias tshuaj hloov pauv yog hais txog kev hloov pauv ntawm txoj hauj lwm ntawm NMR nqus uas tshwm sim vim kev tiv thaiv los yog deshielding ntawm cov protons los ntawm cov electrons ntawm lub compound, whereas coupling tas li hais txog kev sib cuam tshuam ntawm ib khub. ntawm protons.
Hauv qab infographic qhia txog qhov sib txawv ntawm kev hloov tshuaj lom neeg thiab kev sib txuas tas li.
Summary – Chemical Shift vs Coupling Constant
Ob qho tshuaj hloov pauv thiab sib txuas tas li yog cov ntsiab lus uas muab cov lej muaj feem cuam tshuam nrog NMR. Qhov sib txawv tseem ceeb ntawm kev hloov tshuaj lom neeg thiab kev sib txuas tsis tu ncua yog tias lub sij hawm tshuaj hloov pauv yog hais txog kev hloov ntawm txoj hauj lwm ntawm NMR nqus uas tshwm sim vim kev tiv thaiv los yog deshielding ntawm cov protons los ntawm cov electrons ntawm lub compound whereas coupling tas li hais txog kev sib cuam tshuam ntawm ib khub ntawm protons.
