Ethylamine from oxidation

Harley-Mason has shown that 5,6-dihydroxyindole (29) can also be obtained from /9-(2,4,5-trihydroxyphenyl)ethylamine (101). Oxidation of 101 with potassium ferricyanide, buffered with sodium bicarbonate, gives a deep red solution [presumably containing norepinochrome (106)] from which 29 was obtained, after the solution had been allowed to stand under hydrogen for 24 hours.281... 

Dimethylamine and trimethylamine (commercially available), 1,3,5-tri-N-methyl hexahydro-5-triazine (from reaction of formaldehyde and methylamine), tetramethylhydiazine (gift of B. J. Aylett), tetramethylmethylenediamine (from reaction of formaldehyde with dimethylamine), dimethyl- and diethylnitrosamine (from reaction of nitrous acid with the appropriate dialkylamine), diethylmethyl-amine (from reductive methylation of diethylamine), ethylethylideneamine (from reaction of ethylamine and acetaldehyde), and TMT and TET (from oxidation of the appropriate wnst/m-dialkylhydrazine). 

The same type of process using osmylation instead of the Simmons-Smith reaction leads to a synthesis of enantiomerically pure 2,3-dihydroxycycloalkanones from 2-cycloalkenones. Addition of (S)-(141) to 3,S,S-trimethyl-2-cyclohexenone (162) produces a mixture of diastereomers (163a) and (163b), which are easily separable by silica gel chromatography. Treatment of the individual diastereomers with tri-ethylamine N-oxide and 0s04 (5 mol %) afford crude triols. In each case, a single diastereomeric product is produced. The subsequent thermolysis of the diastereomeric triols gives enantiomeric 2,3-dihydroxy-3,5,5-trimethyl-2-cyclohexanones(164 Scheme 37). 

Ethylamine should be stored in a flammable-liquids storage room or cabinet. It should be stored away from oxidizing materials and sources of ignition. It is shipped in steel cylinders or drums. 

This reaction is thermodynamically favorable (for ethylene A 29s = 230). However, it proceeds under unusually drastic conditions. The formation of ethylamine from ethylene and ammonia occurs in the presence of metallic sodium at 473 K and under 40 MPa pressure. At the same temperature, this reaction is also catalyzed by molybdenum oxide. However, the reaction rate is very slow, and at higher temperatures the equilibrium of this reaction is not favorable. 

To minimize the formation of fuhninating silver, these complexes should not be prepared from strongly basic suspensions of silver oxide. Highly explosive fuhninating silver, beheved to consist of either silver nitride or silver imide, may detonate spontaneously when silver oxide is heated with ammonia or when alkaline solutions of a silver—amine complex are stored. Addition of appropriate amounts of HCl to a solution of fuhninating silver renders it harmless. Stable silver complexes are also formed from many ahphatic and aromatic amines, eg, ethylamine, aniline, and pyridine. 

Aldrich and used for all oxidation experiments. TEMPO, sodium hydroxide, sodium sulfide, formaldehyde, ethylamine and methyl-a-D-glucopyranoside were reagent grade or higher and were used as received from Sigma and Aldrich. 

Our attempts to isolate larger amounts of 6 from the solution have failed so far. The mass peak of the sodium adduct of 8 (Mg Na+ = 246.8), however, strongly supports the oxidation of 5 into 6 as a prerequisite for the subsequent formation of 8 from 7 as outlined (eqs. 6 and 7). The addition of ethylamine to capture the reactive aldehyde 6 as imine did not result in recognized reaction products. 

A simple example in this class with which to begin is A,A-diethyl-m-to-luamide 0V,/V-dicthyl-3-mcthylbenzamidc, DEET, 4.82), an extensively used topical insect repellant. The hydrolysis product 3-methylbenzoic acid was detected in the urine of rats dosed intraperitoneally or topically with DEET. However, amide hydrolysis represented only a minor pathway, the major metabolites resulting from methyl oxidation and A-dealkylation [52], Treatment of rats with /V,/V-dicthylbcnzamidc (4.83), a contaminant in DEET, produced the same urinary metabolites as its secondary analogue, A-ethylbenzamide (see Sect. 4.3.1.2). This observation can be explained by invoking a metabolic pathway that involves initial oxidative mono-A-deethylation followed by enzymatic hydrolysis of the secondary amide to form ethylamine and benzoic acid [47], Since diethylamide was not detected in these experiments, it appears that A,A-diethylbenzamide cannot be hydrolyzed by amidases, perhaps due to the increased steric bulk of the tertiary amido group. 

It has been recently described [55d) that aliphatic nitrile oxides can be formed in solution by treating an aliphatic a-nitro-hydrocarbon with phenylisocyanate in the presence of a catalytic amount of tri-ethylamine. Dehydration of the nitro compounds occurs with the con-committant formation of benzoylurea. From nitroethane, the reaction is formulated as follows ... 

In a similar reaction, 2-(o-nitrophenyl)ethylamine (100) may be reduced in an ammonia buffer to the hydroxylamine and oxidized to the nitroso derivative, which condenses with the amino group to a dihydrocinnoline.160,161 It is also possible to prepare dihydrobenzo-l,2,3-triazinones on reduction of o-nitrobenzhydrazide, followed by oxidation of the hydroxylamine to a nitroso group, and 3-phenyldihydrobenzo-l,2,3-triazine (101) from N-phenyl-(V-(o-nitrobenzyl)hydrazine (100) in an analogous way161 [Eq. (78)]. 

Phenyl -tolyl selenide in aqueous suspension is boiled with potassium permanganate for several hours. The manganese mud is dissolved and the 4-carboxydiphenyl selenoxide precipitated by passing in sulphur dioxide. After filtration the precipitate is macerated with dilute sodium carbonate solution, the products of oxidation being separated in this manner into phenyl p-tolyl selenoxide and 4-carboxydiphenyl selenoxide. Addition of dilute sulphuric acid to the sodium carbonate extract causes the separation of 4-carboxydiphenyl selenoxide, which is crystallised from alcohol. The product is a microcrystalline powder, melting with decomposition at 253° to 255° C. Attempts to resolve it into optically active forms have failed the l-menthylamine salt melts at 220° to 222° C. with decomposition, and the d-a-phenyl-ethylamine salt forms feathery needles, M.pt. 194° to 195° C. with decomposition.3... 

A similar technique has been used to determine the acidic character of niobium oxide and niobyl phosphate catalysts in different solvents (decane, cyclohexane, toluene, methanol and isopropanol) using aniline and 2-phenyl-ethylamine as probe molecules [27, 28]. The heat evolved from the adsorption reaction derives from two different contributions the exothermic enthalpy of adsorption and the endothermic enthalpy of displacement of the solvent, while the enthalpy effects describing dilution and mixing phenomena can be neglected owing to the differential design and pre-heating of the probe solution. 

Use of a co-amine is embodied in an improved procedure for the preparation of A -octalin. A mixture of 0.2 mole of naphthalene and 250 ml. each of ethylamine and dimethylamine is placed in a flask fitted with a dry ice condenser, 1.65 g.-atoms of lithium wire cut in half-centimeter pieces is added all at once, and the mixture is stirred magnetically for 14 hrs. The solvent mixture is allowed to evaporate and the grayish white residue (containing excess lithium) is decomposed by cautious addition of about 100 ml. of water with cooling. The precipitated product is collected and the filtrate extracted with ether distillation affords 19-20 g. of hydrocarbon found by VPC analysis to contEiin 80% of A "-octalin and 20% of A -octalin. Isolation of the major product in pure form is accomplished by reaction of the mixture with bis-3-methyl-2-butylborane, which adds selectively to the less hindered A -isomer. Oxidation of the product with hydrogen peroxide to convert the adduct into an easily separated alcohol, followed by distillation, affords A" " -octalin of 99% purity in yield from naphthalene of 50-54%,... 

The preferred alkaline compounds for carrying out my invention are the alkali metal and alkaline earth metal oxides, hydroxides and carbonates, and these compounds are utilized in just sufficient amount to displace the desired amine or amines. It is obvious, of course, that if the mixture of amine salts also contains free mineral acid or an ammonium salt, an additional amoimt of alkali stoichiometrically equivalent to these substances must be added. I have also found that as alkaline reagents for accomplishing this separation it is possible to use other alkylamines or methylamines of different basicity. These amines may be used for displacement together with or in place of the alkalies above mentioned. For example, dimethylamine being more basic than trim-ethylamine may be utilized to displace triethylamine from its hydrohalide salts, when utilized in stoichiometrical proportions. Similarly, diethylamine may be utilized to displace mono and triethylamine from their hydrohalide combinations. 

One of the key advances in column technologies is the development of high-purity silica.1,9 In recent years, it has become a de facto industry standard for almost all new column offerings. This development stems from the realization that batch-to-batch reproducibility and peak tailing of basic solutes are mostly caused by acidic residual silanols. Figure 3.9 shows different types of silanols and their relative acidity. The worst culprits turned out to be the very acidic silanols adjacent to and activated by metallic oxides. Many older silica materials have high metallic contents (e.g., Spherisorb) and are extremely acidic. They often require the use of amine additives in the mobile phase (e.g., tri-ethylamine) to prevent adsorptive interaction with basic analytes. The inherent variations of these active (acidic) silanols are also responsible for the lack of batch-to-batch consistency of these acidic silica materials. 

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