Pyridinium iodides

Mukaiyama s Reagent (2-Chloro-l-methyl pyridinium Iodide or 2-Fluoro-l-methyl pyridinium p-toulenesulfonate)... 

Pyridinium iodide, l-ethyl-4-methoxycarbonyl-UV spectrum, 2, 127 Pyridinium iodide, 1-methyl-decomposition, 2, 300 Pyridinium iodide, 6-pterinylmethyl-synthesis, 3, 312... 

Pyridinium iodide, 4,4 (l,3,4-thiadiazole-2,5-diyl)-bis(l-methyl)-reduction, 6, 564 Pyridinium ion, Af-methyl-as metabolite of pyridine, 1, 234 Pyridinium ions hydrogen bonding to water mass spectrometry, 2, 135 magnetic circular dichroism, 2, 129 NMR, 2, 121... 

Pyrrolo[2,3-6]pyridinium iodide, 1,7-dimethyl-reduction, 4, 508 Pyrrolo[3,2- 6]pyridin-2-ones spectra, 4, 502... 

Kosower made the first use of this phenomenon for measuring solvent polarity. The model process is the absorption transition of l-ethyl-4-carbomethoxy-pyridinium iodide, 7 ... 

Z values are obtained from Eq. (8-76) for solvents having Z in the approximate range 63-86. In more polar solvents the CT band is obscured by the pyridinium ion ring absorption, and in nonpolar solvents l-ethyl-4-carbomethoxy-pyridinium iodide is insoluble. By using the more soluble pyridine-1-oxide as a secondary standard and obtaining an empirical equation between Z and the transition energy for pyridine-1-oxide, it is possible to measure the Z values of nonpolar solvents. The value for water must be estimated indirectly from correlations with other quantities. Table 8-15 gives Z values for numerous solvents. 

Methylation of nicotine to the pyridinium iodide with methyl iodide, followed by its conversion to the hydroxide with silver oxide in water, oxidation with potassium permanganate to the A -methyl nicotinic acid hydroxide and subsequent deprotonation with silver oxide yielded Trigollenine as colorless needles (1897CB2117). In a later publication, the formation of nicotinic acid from nicotine was described. Esterification followed by aminolysis and methylation yielded the A -methylnicotinamide... 

The formation of CdS particles beneath monolayers of A-methyl-p-(p-tetradecyl-oxystyryl)pyridinium iodide, a cationic surfactant with a hemicyanine portion was studied [144]. The monolayers were spread on a circular glass trough coated with paraffin, and the trough was covered by ajar. The CdCL subphase also contained EDTA, so the Cd was... 

The Z scale developed by Kosowct and Mohammad [48,49] is based by the chaige-transfer absorption of Af-ethyl methoxycarbonyl) pyridinium iodide molecule. The wavelength of maximum adsorption (A in nm) is measured and the energy (kcal/mol) of this transition becomes the actual polarity measured for a given solvent (Equation 4.17) ... 

Rhodium catalyzed carbonylations of olefins and methanol can be operated in the absence of an alkyl iodide or hydrogen iodide if the carbonylation is operated in the presence of iodide-based ionic liquids. In this chapter, we will describe the historical development of these non-alkyl halide containing processes beginning with the carbonylation of ethylene to propionic acid in which the omission of alkyl hahde led to an improvement in the selectivity. We will further describe extension of the nonalkyl halide based carbonylation to the carbonylation of MeOH (producing acetic acid) in both a batch and continuous mode of operation. In the continuous mode, the best ionic liquids for carbonylation of MeOH were based on pyridinium and polyalkylated pyridinium iodide derivatives. Removing the highly toxic alkyl halide represents safer, potentially lower cost, process with less complex product purification. 

DMII = N,N-dimethyl imidazohum iodide DEII = N,N-diethyl imidazohum iodide BMII = N-butyl-N-methyl imidazohum iodide [Etpy]I = N-ethyl pyridinium iodide [pyMe]I = N-methyl pyridinium iodide MTOPI = methyl trioctyl phosphonium iodide [BusPMe] = methyl tributyl phosphonium iodide. 

General Procedure for Batch Carbonylation of Methanol in the Absence of Methyl Iodide. A complete set of procedures appears in ref. 5 bnt the following procedure is representative of a methanol carbonylation. To a 300 mL Hastelloy C-276 autoclave was added 0.396 g (1.5 mmol) of RhCl3 3H20, 112.0 g (0.507 mol) of N-methyl pyridinium iodide, 30.0 g (0.5 mol) of acetic acid, and 64.0 g (2.0 mol) of methanol. The mixture was heated to 190°C under 250 psi (1.72 MPa) of 5% hydrogen in carbon monoxide. Upon reaching temperatnre the gas feed was switched... 

As in the earlier examinations, the amount of methyl iodide detected in the purged product was still averaged ca. 0.3 wt.%. However, unlike the earher ran with [MePy]I, we took a close look at the effluent from the operation with l,2-dimethyl-5-ethyl-pyridinium iodide ([DMEpy] ). All the product was distilled overhead leaving a residue that upon examination by NMR contained a ca. 3 1 acetate [DMEpyratio. Closer examination by NMR revealed that only about 3% of [DMEpy]l in the overhead distillate had been dealkylated to 2-methyl-5-ethyl pyridium hydroiodide. 

Bulk NLO studies on luminescent /uc- ReI(CO)3(a-diimine) + complexes by Yam and co-workers note SHG from surfactant derivatives such as (54) and (55) deposited in Langmuir-Blodgett (LB) thin films.110-112 For example, the 532 nm SHG from LB films of the stilbazole derivative (55) is ca. 50% more intense than that from films of the structurally related purely organic salt traiw-.lV-methyl-4-[2-(4-octadecyloxyphenyl)ethenyl]pyridinium iodide.112... 

In another approach to the estimation of solvent polarities the effect of a solvent on the absorbance maximum in the visible-ultraviolet region of the charge-transfer band of a salt such as 1 -ethyl-4-carbomethoxy pyridinium iodide is measured 147). A shift of the maximum to shorter wavelengths occurs as solvent polarity increases. The wavelength, expressed in kcal, is called the Z value of the solvent. This method provides a simple and rapid measure of solvent polarity at the molecular level. 

Mukaiyama reagent such as 2-chloro-l-methyl-pyridinium iodide for esterification or amide formation. 

Artemisyl, Santolinyl, Lavandulyl, and Chrysanthemyl Derivatives.— The presence of (41) in lavender oil has been reported earlier. Poulter has published the full details of his work (Vol. 5, p. 14) on synthetic and stereochemical aspects of chrysanthemyl ester and alkoxypyridinium salt solvolyses (Vol. 3, pp. 20—22) and discussed its biosynthetic implications. Over 98% of the solvolysis products are now reported to be artemisyl derivatives which are formed from the primary cyclopropylcarbinyl ion (93) which results from predominant (86%) ionization of the antiperiplanar conformation of (21)-)V-methyl-4-pyridinium iodide the tail-to-tail product (96 0.01%) may then result from the suprafacial migration of the cyclopropane ring bond as shown stereochemically in Scheme 3. This is consistent with earlier work (Vol. 7, p. 20, ref, 214) reporting the efficient rearrangement of the cyclobutyl cation (94) to (96) and its allylic isomer, via the tertiary cyclopropylcarbinyl cation (95). ... 

Kaiser, S.C. Metabolism of 2-formy1-1-methyl pyridinium iodide... 

Size-quantized CdS was grown in the xerogels Acidic TiO gels, doped by 4-(dimethylamino)-4 nitro-sostilbene and 4 (2-(4-hydroxyphenyl)ethenyl)-N-methyl-pyridinium iodide, were spread on a spinning ITO glass plate. Another ITO plate was placed on the field and an electric field was applied prior to drying in a vacuum. Second-order optical activity was observed 113 114... 

Observations Hydrophobic fluorinated pyridinium iodide ionic solvents lack sufficient... 

PDADMA = poly(diallyldimethylammonium chloride) a positively, PSS = poly(styrenesulfonic acid), PAMPS = poly(2-acrylamido-2-methyl-l-propane sulfonic acid), and PFPVP = 4-vinyl-trideca-fluoro-octyl pyridinium iodide-co-4-vinyl pyridine. 

The spectra of substituted pyridinium iodides are characterized by charge transfer bands involving the interaction of pyridinium and iodide ions. Mukerjee and Rayt showed that this band is shifted about 90 nm toward the red for dodecyl pyridinium iodide, which forms micelles, compared to methyl pyridinium iodide, which does not. They measured max for the micelles in mixed solvents of variable relative dielectric constant and obtained the following results ... 

Estimate the effective dielectric constant at the surface of the micelle from the fact that max occurs at 286 nm for dodecyl pyridinium iodide micelles in water. In light of the value estimated in Section 8.3 for the dielectric constant in the vicinity of solubilized benzene, does it seem likely that the value of er for bulk water applies in the Stern layer ... 

The betaines 297 are easily prepared from a pyrylium salt and the appropriate 4-aminophenol followed by deprotonation. Typically, 2,4,6-triphenyl-pyridinium iodide and 4-aminophenol give the blue-black betaine (297 R = R = Ph, R = H) which also occurs as a red hexahydrate. With methyl iodide this compound gives 7V-(p-methoxyphenyl)-2,4,6-triphenyl-pyridinium iodide. 10,221... 

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