OH IR bands

The FTIR spectra of such a single solution are recorded at five temperatures between —5 and +55 °C. The method requires the preliminary determination of the temperature dependenee of the absorption coefficient, b, of the i (OH) IR band. This quantity falls off linearly with increasing temperature according to Equation 4.24, in which the temperature t is in °C ... 

A-Hydroxy-5-norbornene-2,3-dicarboxylic acid imide [21715-90-2] M 179.2, m 165-166", 166-169", pKesi-6 Dissolve in CHCI3, filter, evaporate and recrystallise from EtOAc. IR (nujol) 1695, 1710 and 1770 (C=0), and 3100 (OH) cm. 0-Acetyl derivative has m 113-114° (from EtOH) with IR bands at 1730, 1770 and 1815 cm only, and the 0-benzoyl derivative has m 143-144° (from propan-2-ol or C6H6). [Bauer and Miarka J Org Chem 24 1293 1959 Fujino et al. Chem Pharm Bull Jpn 22 1857 1974],... 

We have proposed an initiation mechanism for the ROOH-amine system in which some H-bond complex may be formed [36]. Then Sun et al. [37,38] thoroughly investigated the initiation mechanism of ROOH-Amine through IR spectra of TBH-triethylamine, TBH-DMT, and CHP-DMT. From the wideness of the shift of OH absorption bands at 3120, 3336, and 3257 cm were... 

Secondly, the reaction of 89a, 90a, and K2CO3 under solvent-free conditions was monitored by IR spectral measurement. A mixture of 89a, an equimolar amount of 90a, and twice the molar amount of K2CO3 initially showed vC=0 absorption (C) at 1670 cm assigned to the formation of 93 this absorption decreased gradually and new vC=0 absorption bands appeared at 1696 (D) and 1641 cm" (E) (Fig. 2). After 60 min, the C absorption band disappeared and the D and E absorptions increased. After further reaction at 80 °C for 10 min, the D absorption disappeared and only the E absorption remained in the spectrum (VI in Fig. 2). The spectrum VI is identical to that of the final product 91a. The appearance of the D absorption band together with a strong OH absorption band at 3465 cm" suggests production of a ketoalcohol intermediate. 

The frequencies of these vibrations generally decrease in the order v > 8 > y > x. Not all vibrations can be observed absorption of an IR photon occurs only if a dipole moment changes during the vibration. The intensity of the IR band is proportional to the change in dipole moment. Thus species with polar bonds (e.g. CO, NO and OH) exhibit strong IR bands, whereas molecules such as H2 and N2 are not infrared active at all. 

Irrespectively of the iron content, the applied synthesis procedure yielded highly crystalline microporous products i.e. the Fe-ZSM-22 zeolite. No contamination with other microporous phases or unreacted amorphous material was detected. The SEM analysis revealed that size and morphology of the crystals depended on the Si/Fe ratio. The ZSM-22 samples poor in Fe (Si/Fe=150) consisted of rice-like isolated crystals up to 5 p. On the other hand the preparation with a high iron content (Fe=27, 36) consisted of agglomerates of very small (<0.5 p) poorly defined crystals. The incorporation of Fe3+ into the framework positions was confirmed by XRD - an increase of the unit cell parameters with the increase in the number of the Fe atoms introduced into the framework was observed, and by IR - the Si-OH-Fe band at 3620 cm 1 appeared in the spectra of activated Fe-TON samples. 

Figure 4.34 Position of IR band (due to acidic OH groups) with respect to varying Si/AI ratios in different zeolites. (Reprinted from Introduction to Zeolite Science and Practice, Studies in Surface Science and Catalysis, Vol. 58, J.H.C. van Hooff, J.W. Roelofsen, Techniques of Zeolite Characterization, pp. 241-283. Copyright 1991. With permission from Elsevier.)...

The O H stretching spectra of ethanol trimers and larger clusters cannot be conformationally resolved in a slit jet expansion [65, 77, 157], VUV-IR spectra [184] are even broader, sometimes by an order of magnitude, and band maxima deviate systematically by up to +50 cm 1 from the direct absorption spectra. We note that ethanol dimers and clusters have also been postulated in dilute aqueous solution and discussed in the context of the density anomaly of water ethanol mixtures [227], Recently, we have succeeded in assigning Raman OH stretching band transitions in ethanol-water, ethanol water, and ethanol water2 near 3550, 3410, and 3430cm, respectively [228],... 

Work with the objective of comparing oxo-ions with oxide particles in order to test the validity of this reasoning has been reported by Chen et al. who used a catalyst that initially contains Fe oxo-ions, [HO-Fe-0-Fe-OH] +. These sites were first converted to Fc203 particies by a simpie chemical treatment. This was followed by another treatment, which redispersed these Fc203 particies back to oxo-ions. The change in particle size was monitored by a spectroscopic method based on the observation that in zeolites metal ions and oxo-ions, that are attached to the wall of a cage, give rise to a typical IR band caused by the perturbation of the vibrations of the zeolite lattice. 

A simple formula has been proposed which directly relates Av(OH) with Rq o (Bellamy and Owen, 1969) and this has been tested several times and found to hold good (e.g. Helder et al., 1984). For Rq. . o = 244 pm the formula predicts that the ir band for v(OH) would be at 1690 cm which is more in keeping with the broad continuu that underlies the spectra of the P-diketones. Inspection of the ir spectra reproduced in the literature also shows an extreme broadness around the 1600cm region, even though the... 

There is also a noticeable increase in intensity of the aryl-0 band at 1223 cm, especially in the early aging stages. This indicates some association, probably through H-bonding, between the N or OH group and the phenyl ether. It is known that interaction not only shifts the frequency but also increases the intensities of an IR band (11). The association between N and 0 was evidenced by IR spectroscopy (12) and the intensity increase of the 1240cm l... 

It is clear from the above observations that pyridine molecule interacts on the catalyst surface in the following three modes (1) interaction of the N lone pair electron and the H atom of the OH group, (2) transfer of a proton from surface OH group to the pyridine forming a pyridinium ion (Bronsted acidity), and (3) pyridine coordination to an electron deficient metal atom (Lewis acidity). Predominant IR bands, vga and vigb, confirms that the major contribution of acidity is due to Lewis acid sites from all compositions. Between the above two modes of vibrations, Vsa is very sensitive with respect to the oxidation state, coordination symmetry and cationic environment [100]. A broad feature for v a band on Cu containing... 

We have observed similar IR bands (1520, 1352 and 1295 cm ) on the Pt wire/ FSM-16 sample in an in situ IR study of the PROX reaction. From these results, we propose that the selective CO oxidation in the PROX on Pt wire/FSM-16 proceeds through the reaction of a carboxyl intermediate (COOH) on Pt nanowires (and particles) supported on FSM-16 with active OH groups (Figure 15.26). CO reacts with an active silica surface OH of FSM-16 to convert the HCOO intermediate on Pt wires and particles into CO2, thereby leading to selective CO oxidation. The subsequent H2/O2 chemisorption generates active surface OH groups near the Pt wires and particles on FSM-16. Smaller HCOO intermediates due to the smaller OH interaction on Pt particle/HMM-1 and Pt necklace wire/HMM-1 may reflect in their lower TOFs and lower CO selectivity in the PROX reaction (Figure 15.25a and b). 

The UV, IR, and H-NMR spectra of clausine K (clauszoline-J) (51) were almost identical to those of clausine H (clauszoline-C) (50). The most significant difference between their spectra was the presence of IR bands at v ax 3315 (br) and 1666 cm and the absence of one methoxy group resonance in the H-NMR spectrum, which indicated the presence of a carboxy group instead of a carbomethoxy group at C-3 of the carbazole framework. This conclusion was supported by two characteristic mass fragments at m/z 254 (M —OH) and 226 (M" —COOH). The spectroscopic evidence combined with NOE experiments led to structure 51 for clausine K (clauszoline-J). This assignment was confirmed by methylation of 51 with diazomethane to afford clausine H (50) (46) (Scheme 2.11). 

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