NOTES
702
This work has been supported by the Office of Naval Research.
THE CALCULATION OF THE LIMITING RETENTION VOLUME IN GAS-LIQUID PARTITION CHROMATOGRAPHY BY 5.A. GREENE Aerojst-Uensral Corporation, Aausa, California Received November 9, IO66
James and Martin' have shown that the apparent retention volume must be corrected to a limiting retention volume in order to take into account compressibility of the vapor phase and resultant gas velocity gradient down the column. The correcting equation is
Vol. 61
RFis seen to be the ratio of apparent retention time of carrier and zone. Although the method outlined here obviates the correction, "tm is usually a small number as compared to tm and the accuracy of the ratio might not ordinarily be good. It should. also be noted that equation 3 permits the calculation of V , from flow pressure parameters.
i
A
THE PERIODATE OXIDATION OF &+ AND t~ans-CY CLOPENTANEDIOL- 1,Z BY VERNONC. BULGRIN Contribution /rom the Department, of Chemistry, University o/ Wyoming, Laramaa, Wuomwg Received December 1 , I068
The periodic acid oxidative cleavage of vicinal glycols may proceed by at least two mechanisms, usually, however, involving the formation of an intermediate coordination compound between the where oxidant and the reductant, the rate-determining Tro, = limiting retention volume step being the disproportionation of the intera = crowsectional area of gas phase mediate. Duke and Bulgrin'J assigned this type I = column length RF = usual chromatographic meaning of mechanism to the oxidation of ethylene glycol PI = column inlet ressure and a series of methylated ethylene glycols, includPO = column outletpressure volume of gas phase when column is ulnifoi*m1y ing propylene, meso- and levo-butylene and triV, methylethylene glycols. The reaction scheme was packed V m = apparent retention volume suggested Partition coefficientsare calculated from the data of K L products 10,- + G __it C gas-liquid partition chromatography by the expression2 VOIn kV1 v, This scheme leads to the kinetic expression (2? where d[PIT k[C] = ~ ' [ P ] T
-
+
5
Ir
--3
k
dt
artition coefficient Vi = fiquid phase volume =
and the rather tedious correction as in 1 must be made. We define the quantity cVo, as the limiting retention volume of the carrier gas @pI. = F'q, E =. RP 5
V,
(3)
where = apparent retention time of carrier gas which is
measured by a gas such as hydrogen which is negligibly soluble in the liquid
'1
E = 3/2 ( Ppl/pO' 1/P$ - 1
RF = unity for this condition Then vom
= F'tm E =
5
RF
(4)
where tm = apparent retention time of zone
Dividing 3 by 4 we have ? '? !
- 4 ~=+ activity of hydrogen ion
are the res ective activity coefficients ?'IO,- and K l end KDare defined by t t e equilibria Ki HJ06 H + HJOaKD HdIOB2H2O 101[GI = concentration of intermediate [GI = concentration of uncoordinated glycol [PIT = concentration of total periodate
+
F' = carrier gas flow rate ettm
J
where
P
RF
tm
and V", =
v. t m
( I ) A. T. Jamw and A . 3. P. Martin, Biochem. J . , 10, 079 (1962). ( 2 ) P.E.Porter, C , I I . 1)sd and lo. L I . Rtrora, J . Am. Chem. SOC.,7 8 , 2999 (1966).
+
In a study of the effect of p H on the rate of the reaction it was found that for all of the aforementioned glycols, equation 1 was followed down to pH values of less than one, thus substantiating the postulate that a monovalent periodate ion is the reactive species in the acid range. Pinacol, on the other hand, was found to oxidize at a much slower rate than any of the others, and to exhibit a first-order hydrogen ion catalysis. No evidence for any intermediate could be demonstrated from the kinetic data, the reaction being second order over the range of concentrations studied. It was suggested that the same type intermediate does not exist in the case of pinacol, and that the formation of the intermediate has become (1) F. R. Duke, J . A m . Chem. Soc., 69, 30.54 (1947). (2) F. H. Duke atid V. 0.Bulgriu. i b i d . , 7 6 , 8808 (1964).
Ir
L
