Several kinds of model compounds for anomalous linkages in polyurethanes (branching or crosslinking; allophanate and biuret) were prepared. The phenylisocyanate (PHI) based models were identified by IR and NMR. The 13C‐NMR chemical shifts effects due to the anomalous linkages were determined. The 4,4′‐diphenylmethane diisocyanate (MDI) based models were purified incompletely but the characteristic signals of the aromatic carbons were nevertheless found in their spectra. Two types of segmented polyurethane (SPU) were prepared and the anomalous linkages were investigated by 13C‐NMR. The signals due to the allophanate (Al) and the triphenylbiuret (TB) linkages were observed in the spectra of the SPU prepared at high temperature (>80°C) or prepolymer gels yielded by abnormal reaction. A small signal due to a phenyl carbon of biuret (Bi) linkage was observed even in a normally prepared SPU (polyetherurethane‐urea). Employing the phenyl carbon signals was advantageous for the determination of anomalous linkages because of their larger intensities.

SYNOPSISSide reactions of isocyanate groups in N,N-dimethylacetamide ( DMAC ) were studied. Although 4,4'-diphenylmethane diisocyanate (MDI) in DMAC was stable and no changes occurred at 3"C, the isocyanate content decreased and a gel was finally formed a t 40°C. Using phenyl isocyanate ( P I ) as a model compound of MDI, the identification of PI sidereaction products in DMAC were studied. From these experiments, the following five products were identified; ( 1 ) 1,3-diphenylurea (DPU ), ( 2 ) 1,3-diphenyl-5-phenylcarbamyl-6-dimethylaminouracil ( P U R ) , (3) 1,3,5-triphenylbiuret ( T P B ) , ( 4 ) triphenyl-s-triazine-2,4,6-trione (TTT), and ( 5 ) l,l-dimethyl-3-phenylurea (DMPU) . Among these identified products, the novel side reaction product PUR, which was formed between P I and DMAC as solvent, was found along with T P B and TTT, which were already known to cause threedimensional network formation.

Cyclic Trimer of 3,3-Bis(chloromethyl)oxacyclobutaneI n connection with other work in this laboratory we have had occasion to extract polyether powder with acetone. This polymer w&s obtained from the bulk polymerization of 3,3-bis(chloromethyl)oxacyclobutane at 180°C. using AlEt8 as catalyst.The powder of about 100 mesh was extracted in a standard Soxhlet apparatus for 4 hr. Removal of the solvent from the extract gave approximately 2% of a solid, which was then dissolved in a small amount of methanol and the residue, low molecular weight polymer, was filtered o f f . After removal of the solvent from the filtrate, the residue was dissolved in a small amount of acetone and was chromatographed over an alumina column (31 cm. X 3.4 cm., 200-300 mesh A1203) using acetone as the eluant. The collected elute, with a retention time of 45-75 min., was concentrated. After standing a t room temperature for 1 day or longer, white crystalline needles were obtained. These needles, when recrystallized from acetone, melted at 122OC. and were soluble in methanol, benzene, carbon tetrachloride, and petroleum ether.

Abstract:The reaction between butylamines and phenyl isocyanate was studied as a model reaction for the forma-

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