Amines, in various solvents

TABLE 2. Apparent constant of stability of molecular complexes between nitroaromatic derivatives and aliphatic amines in various solvents... 

Abstract—The relative shifts in the frequency of the N—H stretching vibration were measured for a number of amines in various solvents, particularly those in which there is strong interaction. 

The whole process comprising the conversion of an a-halo ketone into a cyclopropanone, the adduct formation, and subsequent ring opening into carboxylic acid derivatives (carboxylic esters, carboxylic acids or carboxylic amides by using alkoxides in alcohols, hydroxides in water or amines in various solvents, respectively) is known as the Favorskii rearrangement. 

Table 2.4. pK values of several common amines in various solvents. 

Solubilities of Normal Saturated Primary Fatty Amines in Various Solvents... 

The self-association of aromatic amines in various solvents and temperatures has been studied extensively and has been summarized by Whetsel. " The formation of dimers and higher-order associations has been proposed. Association in carbon tetrachloride occurs and some authors have found chloroform to be a better choice for analyzing amines in general. 

Two different sets of experimental conditions have been used. Buu-Hoi et al. and Hansen have employed the method introduced by Papa et using Raney nickel alloy directly for the desulfurization in an alkaline medium. Under these conditions most functional groups are removed and this method is most convenient for the preparation of aliphatic acids. The other method uses Raney nickel catalysts of different reactivity in various solvents such as aqueous ammonia, alcohol, ether, or acetone. The solvent and activity of the catalyst can have an appreciable influence on yields and types of compounds formed, but have not yet been investigated in detail. In acetic anhydride, for instance, desulfurization of thiophenes does not occur and these reaction conditions have been employed for reductive acetylation of nitrothiophenes. Even under the mildest conditions, all double bonds are hydrogenated and all halogens removed. Nitro and oxime groups are reduced to amines. 

The H and 13CNMR spectra of various cyclopentazepines have been recorded (Tables 1 and 2), as has the HNMR spectrum of 7V,7V-dimethylcyclopent[e]azepin-l-amine.68 A detailed analysis of geminal and long-range 13C-H coupling constants for cyclopent[c]azepine is also available.87 The HNMR spectra of 9//-pyrrolo[l,2-a]azepin-9-one (8b) and its fully delocalized cation have been recorded in various solvents.7... 

Ester aminolysis and hydrolysis coi Alkylammonium alkanoates. The amine can react nucleophilically or as a general base Rates of decarboxylation compared in various solvents and in aq. micelles, reversed micelles and vesicles M. I. El Seoud et al., 1982 Sunamoto et a/., 1983a... 

Nitrile oxides are oxidized by tertiary amine N-oxides, for example, N-methylmorpholine N-oxide, in various solvents at room temperature to unstable nitrosocarbonyl compounds. In the presence of dienes, such as 1,3-cyclo-hexadiene, they afford Diels-Alder adducts, e.g., 372 fromPhCNO, in fair yields. The mild conditions used in oxidizing a variety of nitrile oxides promise a wide application of this method in synthetic processes (420). 

Table 19 The incoming nucleophile nitrogen KIEs found for Menshutkin reactions with various amines in several solvents.

Table 4.15 gives the equilibrium constants (for extraction, amine) for this reaction with trioctylamine in various solvents. Although the ion pairs are only slightly soluble in water, they can exchange the anion L with other anions, X, in the aqueous phase. (Note that we use L to indicate any anion, while X is used for (an alternative) inorganic anion.)... 

The cyclic molecule Sg is maintained. This is the more usual case and it is observed in various solvents DMSO (dimethyl sulfoxide), DMF (dimethyl formamide), CS2, methanol, and so on, [2, 11, 12]. In this review, we shall denote them as classical solvents. The solutions of sulfur in these solvents are almost uncolored, sKghtly yellow, and absorbing in the UV range. A strong coloration of these solutions would indicate the presence of impurities (e.g. amines) in the solvent. The best evidence that the Sg molecule is kept intact in these solutions is provided by Raman spectroscopy [13, 14]. It must be noted that the rate of dissolution is rather slow the equilibrium is reached, at room temperature, after about one day. 

Schugerl 115] has recently furnished a detail analysis of the reactive extraction of penicdlin-G and V and precursors like phenyl and phenoxy acetic acids. Thirty different amines have been studied for reactive extraction of penicillins 116] in various solvents such as butyl acetate, chloroform, di-isopropyl ether, kerosene, dioctyl ether, etc. Tertiary amines in n-butyl acetate were found to be advantageous because of their low reactivity with solvent but the distribution coefficients of their complexes are significantly lower than those of secondary amines. While using quaternary ammonium salts for ion-exchange extraction, re-extraction is difficult and very large amounts of anion (e.g.. Cl ) are needed to recover penicillins. The basic relationship for distribution coefficient and extraction kinetics have now been fairly developed for amine-penicillin systems. 

Lithiation of a series of cyclic aralkyl tertiary amines (25)—(28) with s-BuLi in various solvents has been studied.72 ortho -Lithiation has been observed only in the case of the eight-membered cyclic amine (28, R = H) and the ease of benzylic lithiation with respect to nitrogen was in the surprising order y > /S a, 8. 

It has been demonstrated that TMS iodide (in combination with cesium fluoride) or TMS triflate in various solvents (THF, MeCN, HMPA) are excellent reagents to promote the generation of azomethine ylids from A-methoxymethyl-A-(trimethylsilylmethyl)aIkyl-amines and their cycloaddition to electron deficient alkenes with yields ranging from moderate to nearly quantitative. The geometry of the double bond in the alkene is preserved in the cycloadduct.410... 

Flash photolysis of a substituted hexaarylbiimidazole and reactions of the imi-dazolyl radical. Coraor, G. R., Riem R. H. MacLachlan, A. Urban, E. J. (Exp. Stn., E. I. DuPont de Nemours, and Co., Wilmington, Del.). J. Org. Chem. 1971, 36 (16), 2272-5. (Eng). The rate of reaction of 2-(o-chlorophenyl)-4,5-diphenylimida-zolyl radicals (L with additives was studied in various solvents. Evidence based on measured rate consts., including kinetic D isotope effects, prove that the rate detg. step in the reaction L + aromatic amine is an electron change reaction at the amino N, while in the reaction L + hydroquinone the rate-detg. step is H abstraction. 

Metals commonly utilized include the alkali metals, mainly lithium, sodium and potassium, and also calcium, zinc, magnesium, tin and iron. Alkali metals and calcium have been used in liquid ammonia," in low molecular weight aliphatic amines," in hexamethylphosphoramide, in ether or in THF containing crown ethers, or in very dilute solutions in polyethers such as 1,2-dimethoxyethane (DME)." Reactions with metal solutions in liquid ammonia often use a cosolvent, such as ether, THF or DME, to increase solubility of the organic substrate in the reaction mixture. These same metals, as well as zinc and magnesium, have been used as suspensions in various solvents including ether, toluene, xylene, etc. 

The authors studied the polymerization of formaldehyde with amines including tertiary amines at —78°C in various solvents (Table 1), and determined the conversion after 15 min reaction time. Tertiary amines are highly reactive initiators for formaldehyde polymerizations even at the level of 10 mole T per mole 1 of formaldehyde. The reactivity of the amine is related to its pXg value but also to the branching of the aliphatic side chains of the substituents on the nitrogen atom. Branched amines, especially when the branching is on the a-carbon atom as in the case of a tertiary butyl group, are less effective initiators than tertiary amines with n-alkyl chains. The pX a of the amine is not the essential feature for an efficient tertiary amine initiator, because pyridine was almost as effective as tri-n-butylamine but quinoline, with a similar pK g as pyridine, is almost inactive (Table 1). 

When radioactive pyridoxine hydrochloride was orally supplemented to evaluate vitamin Be metabolism in adult domestic cats, two unknown radioactive compounds (compounds X and Y) were excreted in the urine.The Rf values of compound X (7 f values 0.95, 0.83, 0.2, 0.5, and 0.62) and compound Y (Rf values 0.35, 0.20, 0.22, 0.32, and 0.25) were identical to those of pyridoxine-3-sulfate and Wmethylpyridoxine, respectively, but not to those of pyridoxine (Rf values 0.73, 0.83, 0.78, 0.52, and 0.62) in various solvent systems [0.5% ammonium hydroxide, 95% ethanol, chloroform-methanol (3 1 vol/vol), isoamyl alcohol-acetone-triethyl-amine-water (24 18 8 6 vol/vol), and 2-butanol-1.5N ammonium hydroxide (3 1 vol/vol), respectively] by TLC on silica gel plates. 

---