Infrared spectroscopy epoxides

Although acetone was a major product, it was not observed by infrared spectroscopy. Flowing helium/acetone over the catalyst at room temperature gave a prominent carbonyl band at 1723 cm 1 (not show here). In this study, a DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) cell was placed in front of a fixed reactor DRIFTS only monitored the adsorbed and gaseous species in the front end of the catalyst bed. The absence of acetone s carbonyl IR band in Figure 3 and its presence in the reactor effluent suggest the following possibilities (i) acetone formation from partial oxidation is slower than epoxidation to form PO and/or (ii) acetone is produced from a secondary reaction of PO. 

Sharpless suggested that epoxidation was catalyzed by a single Ti center in a dimeric complex with a C2 symmetric axis. Molecular weight measurement, infrared spectroscopy, and H, 13C, and 170 NMR spectrometry all suggest that such a dinuclear structure is dominant in the solution phase (Fig. 4-2).10... 

Z.H. Ge, R. Thompson, S. Cooper, D. Elhson and P. Tway, Quantitative monitoring of an epoxidation process hy Eourier-Transform infrared spectroscopy. Process Contr. Qual., 7(1), 3-12 (1995). 

In order to optimize the structure and properties of composites, a knowledge of the polymerization kinetics and mechanism are required. Various approaches have been taken to a determination of the kinetics of the polymerization including infrared spectroscopy 30,31). Although the various epoxide/anhydride/amine systems are... 

One additional special aspect of the infrared spectroscopy of epoxides merits brief mention. It has been observed in at least throe laboratories 10-1J7R-817 that the carbonyl-stretching frequency in... 

Reed 332) has reported that reaction of ethylene oxide with the a,(a-dilithiumpoly-butadiene in predominantly hydrocarbon media (some residual ether from the dilithium initiator preparation was present) produced telechelic polybutadienes with hydroxyl functionalities (determined by infrared spectroscopy) of 2.0 + 0.1 in most cases. A recent report by Morton, et al.146) confirms the efficiency of the ethylene oxide termination reaction for a,ta-dilithiumpolyisoprene functionalities of 1.99, 1.92 and 2.0j were reported (determined by titration using Method B of ASTM method E222-66). It should be noted, however, that term of a, co-dilithium-polymers with ethylene oxide resulted in gel formation which required 1-4 days for completion. In general, epoxides are not polymerized by lithium bases 333,334), presumably because of the unreactivity of the strongly associated lithium alkoxides641 which are formed. With counter ions such as sodium or potassium, reaction of the polymeric anions with ethylene oxide will effect polymerization to form block copolymers (Eq. (80) 334 336>). 

Ge, Z. Thompson, R. Cooper, S. etal., Quantitative monitoring of an epoxidation process by Fourier transform infrared spectroscopy Process Contr. Qual. 1995, 7, 3-12. 

O Brien and Hartman (26) studied the interface of a model system—epoxy resin, regenerated cellulose fibers—by attenuated total reflectance infrared spectroscopy. They compared spectra of the components to spectra of epoxy cured on cellulose and found for the mixture a diminished hydroxyl absorption (3,350 cm 1) and C-0 stretching (1,050 cm"1), and disappearance of the epoxy band (915 cm 1). From this they concluded that covalent bonding does occur between the epoxide groups and cellulose hydroxyls. 

This effect cannot be simply explained by the low degree of filling. Detailed investigations of the reaction mechanism of the composite formation by Al, Si, C NMR spectroscopy, and NIR infrared spectroscopy show that in this system the boehmite acts as a condensation catalyst for the epoxide... 

The use of tritiated imidazoles and epoxides provide more precise information concerning the mechanism of resin synthesis and related problems than traditional methods used, such as scanning calorimetry s and Fourier-transform infrared spectroscopy s . 

ENR, epoxidized natural rubber ESEM, environmental scanning electron microscopy FTIR, Fourier transform infrared spectroscopy GNP, gold nanoparticle NR, natural mbber NRL, natural rubber latex SEM, scanning electron microscopy XRD, X-ray diffraction. 

Gas evolution practically ceases 5-15 min after the beginning of the reaction. However, the process of thermal destruction continues, liquid products of comparatively low molecular weight distilling off from the polymer. In the case of unhardened epoxide resins, the liquid destruction products, according to the data of infrared spectroscopy, represent a mixture of low-molecular fractions of the resin, capable of being converted to the infusible and insoluble state under the influence of hardeners. 

Molecular structure of epoxy resins. Infrared spectroscopy (IR) is used to determine the epoxide content of resins as well as their structure. A compilation of IR spectra of uncured resins has been published (86) and their use in quality control and identification of components of resin blends has been described. Recently, near IR (NIR) has emerged as a useful tool to characterize epoxy resins (87). 

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