Identification of Polyhydric Alcohols in Synthetic Resins by

Identification of Polyhydric Alcohols in Synthetic Resins by Programmed Temperature Gas Chromatography

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Neopentyl glycol 1,4-ButanedioI Reagent peaks

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Figure 1. Separation of polyol acetates following butylamine and acetic anhydride treatment A. 8. C.

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D. Dipropylene glycd E. Trielhylene glycol F. o-Phthalic acid

SIR: Since the presentation of a method ( I ) for the characterization of nine polyhydric alcohols present in alkyd resins and polyesters by programmed temperature gas liquid chromatography (PTGLC), new materials have been encountered for analysis and the method has been expanded to include four additional polyols which were not included in the original investigation: neopentyl glycol, 1,4butanediol, dipropylene glycol, and triethylene glycol. The inclusion of these four materials in the general scheme does not interfere in any way with the identification of those previously studied, since each of the 13 has a distinctive retention time value, as illustrated in Table I. However, the peaks formed by. the reaction products of the butylamine reagent interfere somewhat with the positive identification of one of these polyols, 1,4butanediol, and the resin sample was subsequently treated with a different reagent, benzylamine, in order to form reaction products which do not interfere, &s illustrated by Figures 1 and 2. Figure 1 illustrates the separation of these four polyols by gas chromatography, following treatment with butyl-

Table 1.

Figure 2. Separation of pdyol acetates following benzylamine and acetic anhydride treatment A. 8. C.

Neopentyl glycol 1,4-Butanediol Dipropylene glycol

Relative Retention Data for Polyol Acetates

2nd 2nd Butyl- Benpylamme armne Reagent Reagent Poly01 Acetate Peak = 1 Peak = 1 Propylene glycol 0.68 Ethylene glycol 0.71 Neopentyl glycol 0.84 0.52 1,fl-Butanediol 0.97 0.60 Dipropylene glycol 1.05 0.65 Diethylene glycol 1.16 1.24 Glycerol Trimethylolethane 1.33 Trimethylolpropane 1.37 Triethylene glycol 1.43 0.90" 1.81 Pentaerythritol Mannitol 3.08 Sorbitol 3.24 a Same as first reagent peak.

amine and acetic anhydride, The emergence of 1,4butanediol acetate between the reagent peaks is visible and it is apparent that it might be difEicult to detect small amounts. T o obtain an isolated emergence of the 1,4butanediol, the treatment was repeated; benzylamine was substituted for butylamine in the procedure aa

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Trlethylene glycol and 1 st reagent peak 2nd reagent peak

illustrated in Figure 2, where the new reagent peaks are shown emerging b e tween 23 and 27 minutes. The neopentyl glycol, l,4butanediol, and dipropylene glycol are more clearly deb e d in the chromatogram, but the emergence of triethylene glycol is hidden by the newly formed benzylamine reagent peaks. The substitution of benzylamine for butylamine as reagent causes a shift in the position of the reagent peaks, but the poly01 acetate peaks are not affected. The butylamine treatment will suffice in most cmes. The relative retention values of the four newly investigated polyols when treated with the alternate, benzylamine, are given in Table I. ACKNOWLEDGMENT

The advisory assistance of C. F. Pickett, director of the laboratory, is acknowledged and appreciated. LITERATURE CITED

(1) Esposito, G. G., Swann, M. H., ANAL.CHEM.33, 1854 (1961).

G. G. ESPOSITO Coating & Chemical Laboratory Aberdeen Proving Ground, Md. VOL 34, NO. 9, AUGUST 1962

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