Raman spectroscopy alkylates

Chemical Properties. MSA combines high acid strength with low molecular weight. Its pK (laser Raman spectroscopy) is —1.9, about twice the acid strength of HCl and half the strength of sulfuric acid. MSA finds use as catalyst for esterification, alkylation, and in the polymerisation and curing of coatings (402,404,405). The anhydrous acid is also usefijl as a solvent. 

Ho, M. and Pemberton, J.E., Alkyl chain conformation of octadecylsilane stationary phases by Raman spectroscopy. 1. Temperature dependence. Anal. Chem., 70, 4915,... 

Over the past decades several techniques have been used to obtain direct experimental information on the speciation of peroxo metal complexes heteronuclear NMR, IR and Raman spectroscopy, potentiometry and electrospray ionization mass spectrometry (ESI-MS). Often, more than one technique was used at the same time for acquiring complementary evidence. A significant, although nonexhaustive, list of examples related to several metals is given in Table 2. They include cases with hydrogen peroxide or alkyl... 

Observations were made of lipid-protein phases in which the structure is determined mainly by the protein. Raman spectroscopy is a useful method for structure analysis of such phases. The structures described above were analyzed successfully by an x-ray diffraction technique. Lipid-protein complexes, however, are often amorphous, and alternative methods to study their structures are therefore needed. It was demonstrated that Raman spectroscopy can be used to obtain structural information about lipid-protein interaction (16, 17). It is thus possible to determine the conformation as well as the type of environment of the lipid molecules. With the protein, interpretation is more complicated. It is usually possible to determine whether the complex has the same protein conformation as the component used in the preparation, or, if a change occurs, it may be possible to correlate it with denaturation of the pure protein. For complexes formed by long-chain alkyl phosphates and insu-... 

Gosling of UOP LLC patented the use of Raman spectroscopy to control a solid catalyst alkylation process.54 Based on the measured composition of the stream, specific process parameters are adjusted to bring the composition back to a targeted value. Multiple probes are placed in the process, for example, near a feed stock inlet, in the reaction zone, or after the reactor. In the process discussed, the catalyst can be deactivated faster than an on-line GC can produce a reading. This reason, coupled with obtaining greater process efficiency, is strong motivation for a fast on-line system like Raman. 

Gosling, C.D. Control of Solid Catalyst Alkylation Process Using Raman Spectroscopy, US 6,528,316 Bl Assigned to UOP LLC Filed in 2000. 

IR Spectroscopy. The observation of a solid-solid phase transition in PDHS at the temperature of the UV thermochromic transition generated interest in the nature of the polymer chain conformation at temperatures above or below this critical temperature. A number of techniques have been used to study the solid-state structures of PDHS. Rabolt et al. (25) used IR spectroscopy to monitor the conformational behavior of the alkyl side chains of PDHS and Raman spectroscopy to follow that of the backbone. The IR spectrum of PDHS at +30 °C (Figure 9) consists of sharp, intense bands. When the film of PDHS is heated to +100 °C, the sharp deformation bands typical of a highly ordered hydrocarbon chain become broad and less intense, similar to the behavior observed in the IR spectra of n-alkanes at temperatures above the melting temperature. The data refiect conformational disorder in the side chains at temperatures above the +40 °C transition. After... 

In order to differentiate between these two possibilities the Raman and 13C NMR spectra of the ion were studied10. As Raman spectroscopy is a fast physical method (assuming that vibrational transition rates are faster than any of the hydrogen or alkyl shifts) and the question of possible equilibration versus bridged ion is unimportant. The previously discussed technique of average 13C NMR shifts should be also applicable in this case to differentiate a static nonclassical bridged ion from rapidly equilibrating classical carbenium ions. 

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