Unambiguous ¹³C‐NMR assignments for isocyanate carbons of isophorone diisocyanate and reactivity of isocyanate groups in Z ‐ and E‐stereoisomers

Abstract

SynopsisUnambiguous I3C-NMR assignments for the primary (prim-) and secondary (sec-) isocyanate carbons of isophorone diisocyanate (IPDI) have been made by using two-dimensional NMR measurements. On the basis of the assignments, relative reactivity of the prim-and sec-isocyanate groups with n-butanol was studied by quantitative I3C-NMR analysis. The individual stereoisomers of IPDI (Z-IPDI and E-IPDI) and their equimolar mixture were reacted with n-butanol (IPDI/ n-butanol = 2/1 molar ratio) at 5OoC for 3 days. It was found that the sec-NCO is about 1.6 times more reactive than the prim-NCO in both Z-and E-isomers. Reactivity of the E-isomer was found to be slightly higher than that of the Z-isomer. When di-n-butyltin dilaurate (DBTDL) was used as a catalyst, the reactivity of the sec-NCO became about 12 times higher than that of the prim-NCO with both isomers. In the case of 1,4-diazabicyclo[ 2.2.21 octane (DABCO) catalyst, theprim-NCO was 1.2 times more reactive than the sec-NCO with both isomers. Fig. 3. Urethane carbon region of %NMR spectra: ( a ) Reaction 1 (Z-isomer), (b) Reaction 2 (E-isomer), ( c ) Reaction 3 ( Z -/ E -= 1/1, no catalyst), ( d ) Reaction 4 (Z-/E-= 1/1, DABCO catalyst), ( e ) Reaction 5 ( Z -/ E -= 1/1, DBTDL catalyst).

Preparation of Isophorone Diisocyanate Terminated Star Polyethers

“…Also the molecular weight of the stars was of minor importance: With increasing molecular weight the monostar content remained constant, while the content of bistars increased less than 2% (cf. Table 3, compounds 9, 12,13,14). Within the margin of experimental error (l 5%) the results could be summarized as depicted in Table 5.…”

“…The fractions of the four different isocyanate species in the reaction mixture have been measured by inverse gated 13 C NMR in the presence of chromium(III) acetylacetonate as relaxation agent, using the 13 C NMR peak assignment from ref. [14] In the DBTDL catalyzed reaction of IPDI predominant formation of primary isocyanate end caps is expected. The large peaks at 121.9 and 122.7 ppm ( Figure 2, peaks a and b) were assigned to the primary isocyanate group and the secondary isocyanate group of unreacted IPDI, respectively.…”

“…[10][11][12][13][14] Its generally lower reactivity than the aromatic diisocyanates permits the preparation of water based coatings by deposition from aqueous solution. [15] The used poly(ethylene oxide) is responsible for the high biocompatibility of the coatings, e.g., for medical and laboratory devices.…”

Hydrogenated hydroxy-functionalized polyisoprene (H-HTPI) and isocyanurate of isophorone diisocyanates (I-IPDI): reaction kinetics study using FTIR spectroscopy

“…An unequal reactivity between the primary and secondary NCO groups is usually reported. However depending on the reaction conditions the reactivity difference between the NCO groups were found to be in the range 0.2:1 to 12:1 (secondary:primary) [12,[23][24][25][26][27][28][29]. In particular, Lomölder et al [23] show that the catalyst nature had a dramatic effect on the selectivity of IPDI in the urethane reaction (1,4-diazabicyclo[2,2,2]octane (DABCO) 0.2:1, DBTL 11.5:1).…”

Performance properties of self-curing aqueous-based PU system with tri-glycidyl phosphate curing agent

“…The predominant applications of PU include the coatings, adhesives, sealants, elastomers and etc. [1,2] Conventional solvent-based PU has been developed for more than half century and the techniques have been well defined. However, in recent years, it is due to the environmental impacts and safety, so that the applications of solvent-based PU have been restricted and have been replacing by a solvent-free PU, such as water-based PU and UV-curable PU as the replacement [3][4][5].…”