Ketones infrared spectroscopy

An unusual method for the preparation of syndiotactic polybutadiene was reported by The Goodyear Tire Rubber Co. (43) a preformed cobalt-type catalyst prepared under anhydrous conditions was found to polymerize 1,3-butadiene in an emulsion-type recipe to give syndiotactic polybutadienes of various melting points (120—190°C). These polymers were characterized by infrared spectroscopy and nuclear magnetic resonance (44—46). Both the Ube Industries catalyst mentioned previously and the Goodyear catalyst were further modified to control the molecular weight and melting point of syndio-polybutadiene by the addition of various modifiers such as alcohols, nitriles, aldehydes, ketones, ethers, and cyano compounds. 

In the literature, LB films of chlorophyll a have been investigated by many techniques [21,27,28]. In particular, Chapados et al. [29] have studied the aggregation state of chlorophyll a in LB films with electronic and infrared spectroscopies. Their results suggest many points. First, immediately after the fabrication of the film (time zero) the ketone group C = 0 of one chlorophyll a molecule links to the magnesium of an adjacent chlorophyll a molecule to form a dimer. Each dimer interacts via water with another dimer to... 

Analyses of the chloroform-soluble extracts of the subbituminous coal by Fourier transform infrared spectroscopy (FTIR) showed the presence of a sharp carbonyl absorption peak (1800-1650 cm ) in the extracts from the parent coal and in those obtained at yields less than about 10% wt dmmf. The peak, which is attributed to ketones and carboxylates, disappeared at higher conversions (16). Whitehurst and co-workers (12) established that carbonyl- containing compounds, such as esters and carboxylates, can cleave under thermal treatment to produce CO, CO2 and phenols. They concluded that the evolution of these gases during coal liquefaction could originate from the decomposition of similar oxygen functionalities in the coal. 

The widespread use of infrared spectroscopy at that time was probably due to the observation that many chemical groups absorb in a very narrow range of frequency. Furthermore, within this frequency range, the observed frequency may be correlated to specific chemical structures. For example, aldehydes can be differentiated from ketones by the characteristic stretching frequency of the carbonyl group near 1700 cm-1, and the spectral pattern may be likened to a molecular fingerprint. ... 

Characterization of polymers 5-9 was achieved by XH and 31P NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, UV/visible and infrared spectroscopy, and elemental microanalysis. All the polymers were soluble in common organic media, such as tetrahydrofuran, acetone, and methylethyl ketone. 

IR monitoring of oxidation process. Monitoring lubricants by infrared spectroscopy is a well established technique. The infrared spectra of oxidized (used) engine oil samples can be split into three parts (a) above 1900 cm 1, (b) 1900 to 1500 cm 1, and (c) below 1500 cm"1. The spectral changes in the region between 1900 to 1500 cm 1 in commercial automotive oils (SAE 10W/40, API service SE) operated in a Toyota 20R engine over a 8000 km period were evaluated (Coates and Setti, 1984). Major absorptions bands (1900 to 1500 cm 1) of the spectra are [cm 1] 1732 (oxidation, carbonyl esters), 1710 (oxidation, carbonyl ketones/acids), 1629 (nitrate esters), 1605 (carboxylates) of used oils. 

Infrared spectroscopy has led to the determination of the correct structure for a-(l,2-dithiol-3-ylidene)ketones independently from the... 

Szollosi, G. and Bartok, M. Role of basic and acidic centers of MgO and modified MgO in catalytic transfer hydrogenation of ketones studied by infrared spectroscopy, J. Mol. 

Regarding ozonation processes, the treatment with ozone leads to halogen-free oxygenated compounds (except when bromide is present), mostly aldehydes, carboxylic acids, ketoacids, ketones, etc. [189]. The evolution of analytical techniques and their combined use have allowed some researchers to identify new ozone by-products. This is the case of the work of Richardson et al. [189,190] who combined mass spectrometry and infrared spectroscopy together with derivatization methods. These authors found numerous aldehydes, ketones, dicarbonyl compounds, carboxylic acids, aldo and keto acids, and nitriles from the ozonation of Mississippi River water with 2.7-3 mg L 1 of TOC and pH about 7.5. They also identified by-products from ozonated-chlorinated (with chlorine and chloramine) water. In these cases, they found haloalkanes, haloalkenes, halo aldehydes, haloketones, haloacids, brominated compounds due to the presence of bromide ion, etc. They observed a lower formation of halocompounds formed after ozone-chlorine or chloramine oxidations than after single chlorination or chlorami-nation, showing the beneficial effect of preozonation. 

Different types of carbonyl groups give characteristic strong absorptions at different positions in the infrared spectrum. As a result, infrared spectroscopy is often the best method to detect and differentiate these carboxylic acid derivatives. Table 21-3 summarizes the characteristic IR absorptions of carbonyl functional groups. As in Chapter 12, we are using about 1710 cm-1 for simple ketones and acids as a standard for comparison. Appendix 2 gives a more complete table of characteristic IR frequencies. 

Infrared spectroscopy is extremely useful for identifying aldehydes and ketones. Carbonyl groups absarh In the JR range 1660-1770 cm . with the exact position highly diagnostic of the kind of carbonyl up... 

PCC on alumina (7.5g, 6.1 mmol) is added to a flask containing a solution of citronellol (0.60 g, 3.8 mmol) in 10 mL of n-hexane. After stirring or shaking for up to 3 h (follow the course of the reaction by TLC), remove the solid by filtration, wash it with three 10-mL portions of ether, and remove the solvents from the filtrate by distillation or evaporation. The last trace of solvent can be removed under vacuum. (See Fig. 9 in Chapter 3.) The residue should be pure citronellal, bp 90°C at 14 mm. Check its purity by TLC and infrared spectroscopy. A large number of other primary and secondary alcohols can be oxidized to aldehydes and ketones using this same procedure. 

Infrared spectroscopy is extremely useful in analyzing all carbonyl-containing compounds, including aldehydes and ketones. See the extensive discussion in Chapter 19. 

Mechanistic studies have shown that the tetrahedral intermediate (33) is not stable during the course of the reaction (Scheme 10). By monitoring the reaction mixture with infrared spectroscopy, Mukaiyama demonstrated that the ketone is released before the quench and therefore could compete with the more reactive thiol ester in nucleophilic addition. The authors postulate that selective addition occurs to the... 

In order to provide further evidence for the presence of the carbonyl in the proposed structure, infrared spectroscopy was performed. The IR spectrum showed a C = O stretch at 1670 cm-1 (consistent with an aryl ketone as in the proposed structure of the acid degradant). The IR and NMR spectral data indicated no significant TFA in the acid degradant isolate. The MS, NMR, and IR data were all consistent with the acid degradant structure proposed. 

Results of infrared spectroscopy studies have confirmed that COOH groups, or more precisely carboxylate (COO—), play a prominent role in the complexing of metal ions by humic and fulvic acids. Some evidence indicates that OH, C=0, and NH groups may also be involved (Vinkler et al., 1976 Boyd et al., 1979 Piccolo and Stevenson, 1981). The suggestion has been made (Piccolo and Stevenson, 1981) that, in addition to the above, complexes may be formed with conjugated ketonic structures, according to the following reactions ... 

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