Absorption spectroscopy amines

The effect of antioxidants such as hindered phenohcs, secondary amine, and thioester on the radiation cross-linking efficiency of LDPE has been reported [260]. Amount of cross-linking at a given dose decreases with aU the antioxidants, the thioester being the most effective. IR absorption spectroscopy has been used to demonstrate dose-rate dependence of trani -vinylene unsaturation in irradiated Marlex 50 PE [261]. When the irradiated polymer is stored in vacuum a decrease is observed in trani-vinylene absorbance over a period of several weeks. After high dose-rate irradiation the decay is preceded by an initial increase. These phenomena have been ascribed to the reaction of trapped radicals. 

BEER-LAMBERT LAW ABSORPTION SPECTROSCOPY ISOSTERIC AMINES AS CARBOOATION ANALOGUES ISOSTERY "ISOTER,"... 

The ultra-violet light induces electromagnetic excitation in molecules absorbing the laser energy, and by subsequently applying the principle of absorption spectroscopy, kinetic and spectroscopic information relating to the electronically excited states of various energetic molecules have been derived. The systems studied to-date include s-TNB, s-TNT, triphenyl-amine, and mono- as well as di-nitronaphthalenes (Ref 13, 14, 20, 21 28)... 

Concerning the analysis of different types of ion pairs and their discrimination using picosecond absorption spectroscopy, the work by Peters must be emphasized. He studied in great detail the photoreduction of benzophenone by aromatic amines... 

Alpdogan and Sungur [50] developed an indirect atomic absorption spectroscopy method for the determination of mefenamic and flufenamic acids, and diclofenac sodium, based on the complexation with copper (II) amine sulfate. The complex was extracted into chloroform, and the concentrations of substances were determined indirectly by AAS measurement of copper after re-extraction into 0.3 N nitric acid solution. The developed method was applied to the assay of the substances in commercial tablet formulations. The results were statistically compared with those obtained by HPLC method by t- and F tests at 95% confidence level. Calculated t and F values were both lower than the table values. 

The first two derivatives in the series, monuron and metobromuron, are related to the 4-haloanilines. Their primary photochemistry has been studied by Boulkamh and Richard by means of nanosecond absorption spectroscopy [80]. The transients detected from both compounds in aqueous solution could be assigned to the N-substituted 4-iminocarbene, imino-p-benzoquinone-O-oxide and anilino radical from a complete analogy of their spectral and reactive behavior with that of the species obtained from 4-chloroaniline [55,57]. The quantum yields of carbene formation were determined to be = 0.051 for monuron and

halogen-substituted phenylurea derivatives underwent the same heterolytic dehalogenation process as the 4-haloanilines, which could be understood with reference to the protonability of the amine nitrogen, as in the case of 4-chloro-N,N-dimethylanilinc [55]. 

Triplet production in the quenching of aromatic hydrocarbon fluorescence by amines has usually been monitored by flash photolysis. A particularly good example is the study of the quenching of the excited singlet state of pyrene by l,4-diazabicyclo[2.2.2]octane in cyclohexane solutions (Delouis et al., 1979). Fluorescent exciplex formation is not observed with this system but triplet formation does occur. By triplet-triplet absorption spectroscopy... 

The primary intermediates formed from the benzophenone triplet state in the presence of tertiary amines such as dimethylaniline have been observed by picosecond transient absorption spectroscopy [99]. The initial step of the process involves one-electron transfer from amine (dimethylaniline, DMA) to the triplet state... 

Optical absorption spectroscopy of organic radical cations was pioneered by Hoijtink and coworkers and others before the advent of PE spectroscopy, but it was limited for a long time to aromatic amines, polycyclic aromatic hydrocarbons and similar compounds whose radical cations could be generated under stable conditions by chemical oxidation. It was observed that many colourless neutral compounds give rise to intensely coloured radical cations which indicates that excited states of these reactive species lie generally at much lower energy than those of the neutral parent molecules (the most famous example is perhaps Wurster s blue, the radical cation of the colourless tetramethyl-p-phenylenediamine). 

Co = Catechol oxidase He = Hemocyanin Tyr = Tyrosinase MePy2 = Al,Al-bis(2-pyridylethyl)methylamine TACN = 1,3,5-triazocyclononane TMPA = Tris[(2-pyridyl) methyl]amine XYL-0 = a, a -bis[Al,Al-bis(2-pyridylethyl) amino]-m-xylene-2-olate XYL = a, a -bis[Al,Al-bis(2-pyri-dylethyl)amino]-m-xylene XYL-R = Meta substituted a,a bis[Al,Al-bis(2-pyridylethyl)amino]-m-xylene N3 = N, N, Al, Al -Tetrakis-(2-pyridin-2-yl-ethyl)-propane-1,2-diamine N4 = Al,Al,Al, Al -Tetrakis-(2-pyridin-2-yl-ethyl)-butane-1,2-diamine N5 = Al,A,lV, Al -Tetrakis-(2-pyridin-2-yl-ethyl)-pentane-1,2-diamine HB(3,5-Pr2pz)3 = Hydrotris(3, 5-diisopropyl-l-pyrazolyl) borate XAS = X-ray absorption spectroscopy EXAFS = Extended X-ray absorption fine structure rR = resonance Raman. 

In previous studies [3, 4], we had pointed out that the interphase formation mechanisms result from dissolution of the metallic surface layers, concomitantly with ion diffusion through the liquid prepolymer. In order to detect the dissolution phenomenon, pure amine (either DETA or IPDA) was previously applied to chemically etched metallic sheets (either A1 or Ti alloys were used, and had hydroxidic surfaces). After 3 h, the metallic surfaces were scraped with a PTFE spatula. The modified amine (i.e., the amine reacted with the metal) was analyzed. Whatever the natures of the amine and the metal were, metal ions were detected in the modified amines by ICP analysis and new peaks were detected by infrared spectroscopy [5]. To indicate hydroxide dissolution, a very thin layer of liquid amine was applied to chemically etched aluminum, and Infrared Reflection - Absorption Spectroscopy (IRRAS) spectra were recorded every 5 min (the hydroxide band intensity variation at ca. 3430 cm was followed). The OH group peak intensity decreased when the amine-metal contact time increased [5]. Conversely, if pure DGEBA monomer was apphed to the metal surfaces, even after 3 h in contact with the metallic surfaces, no metal ion was detected by ICP in the DGEBA recovered, and the infrared spectra remained identical before and after the contact with the metal. Finally, if pure amine monomer was applied to gold-coated substrates, no chemical reaction was observed (by either IGP or FTIR analyses). 

A variety of aryl and diarylalkene radical cations have been generated in solution and characterized using transient absorption spectroscopy. Many of these are sufficiently long-lived for detailed kinetic studies of their intermolecular reactivity under conditions that are comparable to those used in mechanistic and synthetic studies. Reactions with nucleophiles typically occur by either addition or electron transfer, with the latter dominating in cases where the oxidation potential of the nucleophile is lower than that of the alkene. The data summarized herein indicate that most arylalkene radical cations are unseleclive in their additions to anionic nucleophiles in nonprotic solvents. By contrast, the additions to neutral nucleophiles such as alcohols and amines cover a range of timescales and clearly demonstrate the... 

The bis-porphyrin forms a cleft which, after complexation with Zn(II), acts as a receptor for a,o>-diaminoalkanes. For example 1,12-diaminododecane is bound with an association coiLstant of K. = 7.0 x 10 mol L. When a first-generation dendritic polyamine bearing four terminal primary amine groups is used as a guest, two receptor molecules assemble in such a way that they encapsulate the small dendrimer molecule, as in 50 (Figure 28). This was proven by titration studies, using H NMR and UV-vis absorption spectroscopy. 

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