2-Amino-3-bromo-6-chloropyrazine CAS 212779-21-0

Pyrazines tuaj yeem raug cais raws li lawv cov khoom hloov pauv, nrog ntau hom xws li: alkylpyrazines (xws li 2-methylpyrazine, 2-ethylpyrazine, 2,3-}dimethylpyrazine), alkoxy-pyrazines (xws li methoxypyrazine, ethoxypyrazine) , acylpyrazines (xws li acetylpyrazine), thiab poly-hloov pyrazines nrog ntau yam kev sib txuas ntawm pawg alkyl ntawm lub nplhaib pyrazine; Cov no feem ntau pom muaj nyob rau hauv cov khoom noj xws li kas fes, roasted txiv ntseej, thiab ci khoom, pab txhawb rau lawv cov yam ntxwv aroma thiab tsw.

Cov piv txwv tseem ceeb ntawm pyrazine hom:
Yooj yim alkylpyrazines:
2-Methylpyrazine
2-Ethylpyrazine
2, 3-Dimethylpyrazine
2, 5-Dimethylpyrazine

L-rhamnose nrog thiab tsis muaj leucine
Thaum pib, 1.64 g ntawm L-rhamnose, 5 mL ntawm NH4OH thiab 4.5 mL ntawm H2O tau tshwm sim nrog thiab tsis muaj leucine (0.4 g) ntawm 110 degree rau 2 teev. Tag nrho cov pyrazines tau eluted los ntawm kem nyob rau hauv 5-15 min, thiab cov chromatograms muaj feem xyuam rau cov neeg sawv cev ntawm cov profiles rau cov pyrazines tau los ntawm tag nrho cov kev tshwm sim thiab cov qauv npaj. Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias DCM extract ntawm cov tshuaj tiv thaiv uas muaj leucine pom muaj ntau ceg pyrazines xws li 2-isoamyl-6-methylpyrazine, nrog lub sij hawm elution ntawm 9.54 min piv rau DCM extract ntawm ib zoo li cov tshuaj tiv thaiv tsis muaj leucine. Tsis tas li, DCM extract ntawm ob qho tib si tshuaj tiv thaiv cov khoom tau pom tias muaj qhov tsis xav tau 4-methyl imidazole nrog lub sijhawm elution ntawm 13.95 min.

HFCS + leucine
Kwv yees li 3 g ntawm HFCS tau sib xyaw nrog 0.8 g ntawm L-leucine, 10-12 mL ntawm NH4OH thiab 8-10 mL ntawm H2O. Cov sib tov yog rhuab rau 2 teev ntawm 110 degree. Tom qab cov tshuaj tiv thaiv tiav, 5 g ntawm sodium chloride tau yaj hauv qhov sib tov, uas tau muab rho tawm 4 zaug nrog 25-35 mL ntawm hexane. Tom qab rov ua dua hexane extractions, qhov sib tov tau muab rho tawm rau lub sijhawm thib tsib nrog 90/10 hexane / DCM thiab thaum kawg nrog DCM nkaus xwb. Nrog txhua hexane rho tawm, qhov concentration ntawm pyrazines tshwm sim kom txo. Hauv qhov no, feem ntau ntawm cov alkyl hloov pauv cov ceg ntoo pyrazines tau muab rho tawm thaum thawj thiab thib ob hexane extractions. Kev siv 90/10 hexane/DCM extract ntawm tib cov tshuaj tiv thaiv cov khoom tsim ib qho extract nrog ntxiv pyrazines thiab undesirable 4-methylimidazole (tR=13.94 min). Kev soj ntsuam ntawm qhov kawg 100% DCM extract ntawm tib cov tshuaj tiv thaiv cov khoom qhia tsis muaj pyrazines. Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov tias lub ncov loj, uas eluted nrog tR=12.89 min, tuaj yeem raug xa mus rau 5-methyl-2-pyrazinylmethanol.

CDS nrog thiab tsis muaj leucine
Tag nrho ntawm 10 g ntawm CDS, cov tshuaj aqueous uas muaj 25% fructose, 45% qabzib thiab 0.65% sucrose, tau los ntawm RJ Reynolds Tobacco Company, tau tov nrog 20 mL ntawm NH4OH thiab 10 mL ntawm H2O. Qhov sib tov yog rhuab ntawm 110 degree rau 2 teev. Cov tshuaj tiv thaiv sib tov tau txias tom qab uas 5 g ntawm NaCl tau yaj, tom qab ntawd los ntawm kev rho tawm rau lub sij hawm nrog cov ntshiab hexane tshiab, nyob rau hauv qhov ntau ntawm pyrazines poob, raws li pom saum toj no. Ceg pyrazines, zoo li cov isoamyl derivative tau piav saum toj no, tsis tau kuaj pom vim tsis muaj cov amino acid siv. Qhov kev rho tawm kawg tau ua tiav siv 100% DCM, uas qhia cov pyrazines ntxiv.

Tib cov tshuaj tiv thaiv tau rov ua dua nrog 1 g ntawm leucine. Tom qab tshem tawm cov tshuaj tiv thaiv, 5 g ntawm NaCl tau ntxiv thiab muab rho tawm 5 zaug, thawj zaug nrog 25 mL ntawm hexane tshiab thiab tom qab ntawd 100% DCM. Cov txiaj ntsig zoo thiab cov txiaj ntsig txheeb ze txog cov pyrazines tsim los ntawm cov tshuaj tiv thaiv no zoo ib yam li cov lus piav qhia hauv cov tshuaj tiv thaiv 2 saum toj no. Raws li cov kev sim saum toj no, cov kev rov ua dua tshiab (~6) yuav tsum tau tshem tawm tag nrho cov pyrazines.