Estimation of Primary-Secondary Hydroxyl Ratio and Rate Constants of Alkylene Oxide Polyethers SIR: Hanna and Siggia (2) have recently published a paper on a kinetic differential method for primary and secondary hydroxyl group content of polypropylene glycols. Describing the use of two different reagents for the determination, phenyl isocyanate and acetic anhydride, they found the latter more convenient and precise. The writer has for some time been using a similar method but with the phthalic anhydride reagent (1). I n some cases this reagent is preferable t o acetic anhydride, because aldehydes and phenols do not interfere as with the latter. A reaction temperature of 25' C. was required with the phthalic anhydride reagent when the relative primary hydroxyl was 20y0 or less. For relative primary hydroxyl contents greater than 20% a reaction temperature of 35" C. was required (Table I). Confirmation of the validity of the method was established b y calculation of rate constants from the data obtained from the phthalation of primary and secondary hydroxyl in polyethers. The rate constants are given in Table 11. The primary constants are all of the same order of magnitude, while the secondary constants all group together in a lower order of magnitude.
Table 1.
Temperature, C. 25 25 25 25
O
25 25 25 35 35 35 35 35
%
The same time is required to perform this analysis using the phthalic anhydride reagent as when using the acetic anhydride reagent.
Absolute
LITERATURE CITED
-2
(1) A.S.T.M. D-1638-59T, "h1ethods of Testing Urethane Foaiii Raw Ma-
-
Analyses of 1 and 2-Octanol Mixtures
l-Octanol, 53 Present Found 17 I5 15 12 20 17 20 17
Table II.
11
25 50 6 15 25 51 50
Error,
-3
-3 -3 0
11
20 30
- 20
-5
11 22
1-7
f 8
27 51
+2 0
-2
48
terials," 1959 Supplement, 9 , 120, American Society for Testing Jlatenals, Philadelnhia. r -1959 --(2) Hanna, J. G., Siggia, Sidney, J . Polymer Sci. 56, 297-304 (1962). M.s. B u m Research Laboratory Solvay Process Division Allied Chemical Corp. Syracuse 1, N. Y. 7
Phthalation Rate Constants for Primary and Secondary Hydroxyl Temperature, Primary constant, k,, Secondary constant, kz,
Material c. liters/mole minute I-Octanol 25 3 . 7 x 10-2 2-Octanol 25 Carbowax 600. 25 6 . 7 'x' IO-? Voranol, CP-35OOb 25 6.7 x Kiax PPG-2025. 25 3.2 x 25 7.2 X Acto1 31-56' 25 10.0 x 10-2 Experimental 1-Octanol 35 4.9 x 10-2 35 ... 2-Octanol a Union Carbide Corp. b Dow Chemical Co. National Aniline Division, Allied Chemical Corp. O
liters/mole minute 4.1
x'io-3
6 . 1 x '10-8 2 . 1 x 10-8 1 fi x 10-3 6.8 X 7 . 5 X'10-a
Determination of Oxides and Nitrides in Lithium Metal by High-Temperature Fluorination with Potassium Bromotetrafluoride SIR: Goldberg, Meyer, and White
(4) reported a method for the determination of oxides in fluoride salts and in metals. Reference was made to the fact that both oxygen and nitrogen could be determined b y passing the collected gases through a copper furnace to remove oxygen ( 2 ) . The residual nitrogen would then be measured manometrically. Since that item was published, a hot-copper-by-pass tube has been adfled between the fixed confining volume of the measuring system and the inlet to the Toepler pump as pictured in Figure 1 of that publication. The gases are recycled through the hot-copper tube after measuring the total volume. The residual nitrogen is then measured, and the oxygen is determined by difference. The analysis of lithium for oxygen has been a controversial issue since the amalgamation (5) and butyl bromide (7) techniques, normally used for the
determination of oxygen in the alkali metals, are not satisfactory for lithium. A suitable method exists for the determination of nitrogen in lithium (S), and methods have been reported for the determination of oxygen in lithium (1, 6). However, both analyses cannot be made on the same sample, and it is difficult t o take replicate samples of lithium and maintain a reasonable degree of precision in the results of the analysis. Because the KBrF4 method had been modified so that both oxygen and nitrogen could be determined from one sample, attention was given to the analysis of lithium metal by this method. Several factors had to be considered. The lighter metals, such as beryllium and aluminum, react with KBrF4 t o form finely divided metal fluorides which on occasion plug the valves connecting the reactors to the manifold. A sample of lit,hium weighing a few
hundred milligrams is large in size because of the low density of the metal. The heat generated from the reaction of this large mass of lithium and A uorine a t 450" C. could cause a rupture due t o the sudden increase in pressure within the reactor and the possible localized heating of a small section of the wall of the reactor, as has occurred with a large sample of zirconium metal. Then, there is the problem of transferring the sample of lithium to the reactor.
Table I.
Results from Replicate Analy-
sis of Two Different Samples of LP Oxygen, Nitrogen, % % Sample 1 1.5 0.073 1.7 0.067 Sample 2 0.114 0.010 0.115 0.013
VOL. 34, NO. 10, SEPTEMBER 1962
1343
