FOR THE FOLLOWING COMPOUNDS: 1-pentanol, 2-hexanone, heptane, octane, nonane, de
ID: 567685 • Letter: F
Question
FOR THE FOLLOWING COMPOUNDS: 1-pentanol, 2-hexanone, heptane, octane, nonane, decane
Use the Retention Index Table below to determine the elution order of the above compounds from columns containing (a) (diphenyl)0.35(dimethyl)0.65-polysiloxane, (b) poly(ethylene glycol), and (c) poly(dimethylsiloxane);
TABLE 23-3 Retention indexes for several compounds on common stationary phases Retention index OH Pyridine 1-Nitropropane b.p. 132°C Benzene Butanol 2-Pentanone b.p. II6°C Phase Poly(dimethylsiloxane) (Diphenyl)o os(dimethylos b.p. 80°C b.p. 102°C 737 670 691 657 708 648 664 (DiphenyDa 3s (dimcthyo.6s (Cyanopropylpheny)o.1 (Diphenyl)o.os(dimethy)o3s Poly(ethylene glycol) polysiloxane polysiloxane (dimethyl)o.s polysiloxane polysiloxane 672 754 726 797 956 773 779 1 142 784 824 987 745 871 880 941 1 217 761 879 852 943 1 185 (Biscyanopropyo.9 1 061 1 232 1 174 1 409 1 331 (cyanopropylpheny)o.i polysiloxaneExplanation / Answer
Elution order of compounds on column usinf retention index.
(a) (diphenyl)0.35(dimethyl)0.65-polysiloxane - is a nonpolar stationary phase. therefore more polar compound (with low interaction with this phase) would elute first and last would be most nonpolar compound.
elution order : (first to elute) Butanol, benzene, 2-pentanone, 1-nitropropane, pyridine (last to elute)
(b) poly(ethylene glycol) : is a polar stationary phase, so polar compounds would stick to greater extent and elute at the end.
Elution order (first to elute) benzene, 2-butanone, pyridine, 1-nitropropane, butanol (last to elute)
(c) poly(dimetholsiloxane) : is a nonpolar support, so nonpolar compound would stick and elute at the end.
elution order (first to elute) butanol, benzene, 2-pentanone, 1-nitropropane, pyridine (elutes last)
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