Triethylamine, decomposition

Kikuchi et al. have observed that the initial attack of amine occurs at the carbonyl carbon, resulting in the formation of an ionic intermediate 26. This reaction is very sensitive to the solvent polarity. Under nitrogen atmosphere, intermediate 27 is further aminated to give 28. Oxidation of 27 and 28 gives 23 and 24, respectively. Oxidation in nitrobenzene, however, results in dealkylation products. In the presence of air and triethylamine, decomposition of aminoanthraquinones occurs. 

In the presence of triethylamine, decomposition of the ir-allylic complexes to conjugated dienes may occur, particularly when electron-withdrawing substituents are present on a methyl group in the 1- or 3-position of the iT-allyl system.31 Cyclic alkenes and vinylpalladium chlorides also yield iT-allylic complexes in the absence of an amine. If a tertiary amine is present, however, l,4-dienes are obtained (equation 1l).32... 

Chemical off—on switching of the chemiluminescence of a 1,2-dioxetane (9-benzyhdene-10-methylacridan-l,2-dioxetane [66762-83-2] (9)) was first described in 1980 (33). No chemiluminescence was observed when excess acetic acid was added to (9) but chemiluminescence was recovered when triethylamine was added. The off—on switching was attributed to reversible protonation of the nitrogen lone pair and modulation of chemically induced electron-exchange luminescence (CIEEL). Base-induced decomposition of a 1,2-dioxetane of 2-phen5l-3-(4 -hydroxyphenyl)-l,4-dioxetane (10) by deprotonation of the phenoHc hydroxy group has also been described (34). 

Benzyl chloride undergoes self-condensation relatively easily at high temperatures or in the presence of trace metallic impurities. The risk of decomposition during distillation is reduced by the use of various additives including lactams (43) and amines (44,45). Lime, sodium carbonate, and triethylamine are used as stabilizers during storage and shipment. Other soluble organic compounds that are reported to function as stabilizers in low concentration include DMF (46), arylamines (47), and triphenylphosphine (48). 

The submitters report that both l,4-diazabicyclo[2.2.2]octane and triethylamine have been used to catalyze this decomposition. Tri-ethylamine was less satisfactory as a catalyst because of its relatively rapid reaction with the solvent, carbon tetrachloride, to form triethylamine hydrochloride and because of difficulty encountered in separating triethylamine from the dicarbonate pi oduct. The 1,4-diazabicyclo-[2.2.2]octane was efficiently separated from the dicarbonate product by the procedure described in which the crude product was washed with very dilute aqueous acid. 

Reactions of alcohols with sulfur tetrafluoride, because of decomposition and/or polymerization, usually do not give fluorinated products However, in the presence of a hydrogen fluoride scavenger like triethylamine or pyridine, even such sensitive substrates as benzylic alcohols [555], 2-phenylethanol, and 2-furylmethanol [554] can be fluorinated to give the expected fluoro derivatives (equation 73)... 

After the reaction, 1 ml of water was added to the reaction mixture, and the mixture was adjusted to a pH of 1,0 with concentrated hydrochloric acid while being cooled, and then stirred for 30 minutes. The insoluble matters were filtered off, and the filtrate was adjusted to a pH of 5.5 with triethylamine. This solution was concentrated under reduced pressure, and the residue was diluted with 20 ml of acetone to precipitate white crystals. The crystals were collected by filtration and washed with ethanol to obtain 1.46 g of white crystals of7-[D(-)-0 -emino-(4-hydroxyphenyl)acetamido]-3-methyl-3-cephem-4-carboxylicacid having a decomposition point of 197°C. 

To this acid was then added 1 g of 4-ethyl-2,3-dioxo-1-piperazinocarbonyl chloride (from the reaction of N-ethylethylenediamine and diethyl oxalate to give 2,3-dioxo-4-ethyl-piperazine which Is then reacted with phosgene) and the resulting mixture was reacted at 15°C to 20°C for 2 hours. After the reaction, a deposited triethylamine hydrochloride was separated by filtration, and the filtrate was incorporated with 0.4 g of n-butanol to deposit crystals. The deposited crystals were collected by filtration to obtain 1.25 g of white crystals of 6-[ D(—l-Ct-(4-ethyl-2,3-dioxo-1 -piperazinocarbonylaminolphenylacetamido] penicillanic acid. Into a solution of these crystals in 30 ml of tetrahydrofuran was dropped a solution of 0.38 g of a sodium salt of 2-ethyl-hexanoic acid in 10 ml of tetrahydrofuran, upon which white crystals were deposited. The deposited crystals were collected by filtration, sufficiently washed with tetrahydrofuran and then dried to obtain 1.25 g of sodium salt of 6-[D(—)-a-(4-ethyl-2,3-di-0X0-1-piperazinocarbonylaminolphenylacetamido] penicillanic acid, melting point 183°C to 185°C (decomposition), yield 90%. 

Intermediate 37 can be transformed into ( )-thienamycin [( )-1)] through a sequence of reactions nearly identical to that presented in Scheme 3 (see 22— 1). Thus, exposure of /(-keto ester 37 to tosyl azide and triethylamine results in the facile formation of pure, crystalline diazo keto ester 4 in 65 % yield from 36 (see Scheme 5). Rhodium(n) acetate catalyzed decomposition of 4, followed by intramolecular insertion of the resultant carbene 3 into the proximal N-H bond, affords [3.2.0] bicyclic keto ester 2. Without purification, 2 is converted into enol phosphate 42 and thence into vinyl sulfide 23 (76% yield from 4).18 Finally, catalytic hydrogenation of 23 proceeds smoothly (90%) to afford ( )-thienamycin... 

Transmetallation reaction, 484 Tribenzylamine, decomposition of, 423 Triblock copolymers, 7 Triethylamine, resole syntheses catalyzed with, 405-406... 

In fact, fluorinated polyphosphazenes are usually considered to be extremely stable towards chemical agents and aggressives due to the presence of C-F bonds in the side phosphorus substituents. PTFEP, for instance, appears to be completely insensitive to several, most common, solvents (aliphatic and aromatic hydrocarbons, alcohols and water), to acids (e.g. acetic acid), and to bases (e.g. pyridine and concentrated NaOH solutions), although some decomposition could be observed in triethylamine and in concentrated H2SO4 [41]. Phos-phazene fluoroelastomers, moreover, are known to be completely insoluble in aromatic solvents [533] and petroleum-resistant materials [502-506,552]. 

Hydrolysis was avoided by addition of triethylamine (3-5%) to the eluent for chromatography. Compounds endo/exo-88e and endo/exo-89e were separated without decomposition in this way. Attempts to enhance the endo selectivity by... 

These effects undoubtedly increase thermal stability of SENAs (many of these compounds are distilled in vacuo at temperatures higher than 100°C, see Table 3.7). At the same time, SENAs are hydrolytically highly unstable (see Section 3.4.2.2.). Besides, these compounds can undergo spontaneous decomposition for unknown reasons. It is known that acidic impurities facilitate these processes, whereas triethylamine, on the contrary, stabilizes SENAs (191). Hence, SENAs are recommended to be either stored in a refrigerator with full protection from atmospheric moisture or used in situ. 

First, a-nitrosoalkenes can be generated from BENAs in the presence of bases, for example, of triethylamine (499), which can initiate chain decomposition of these nitroso acetals (Eq. 1). Then, the more active trialkylsiloxy anion is involved in this process. (Apparently, this is responsible for the well-known spontaneous decomposition of BENA in the presence of nitrogen bases.)... 

Grotewold et al4 determined kt by studying the decomposition of borine carbonyl in the presence of triethylamine. At constant total pressure the process may be described by reactions (1), (3) and (4)... 

A more elaborate but general procedure for esterification involves reaction of the A-alkoxycarbonylamino acid with the alkyl chloroformate of the alcohol to be esterified in the presence of triethylamine and a catalytic amount of 4-dimethylami-nopyridine (see Section 4.19) (Figure 3.21). The product probably arises by acylation of the alcohol by the acylpyridinum ion, both originating from decomposition of the mixed anhydride. The method can be used also to prepare activated esters (see Section 2.09), though the latter are usually obtained using the common coupling techniques (see Section 7.7).47 57... 

FIGURE 3.21 Esterification by decomposition of a mixed anhydride by triethylamine in the presence of 4-dimethylaminopyridine.55 The active intermediate is probably the acylpyridium ion. 

The manner in which a carbene was generated was found to be critical to the product distribution in a synthesis of 4(5//)-thiooxazolones (Scheme 6.9). Treatment of diethyl bromomalonate with excess triethylamine in the presence of benzoyl isothiocyanate afforded a mixture of the 4(5//)-thiooxazolone 25 (44%) and the 1,3-oxathiole 26 (minor). However, if the carbene was generated via copper-catalyzed decomposition of diethyl diazomalonate, then 26 was isolated as the major product, albeit in low yield (22%). 

Pyrazoline 68 is converted into the V-acetyl derivative 69 by treatment with acetic anhydride and triethylamine at —5 °C (Scheme 5). Treatment of 68 with acetic acid at 40 °C caused decomposition of the dihydrotriazole ring to give the enamine 71 <1997TL5891>. Treatment with trifluoroacetic acid in dichloromethane at room temperature, however, caused decomposition of both the dihydrotriazole and the oxazolidine rings yielding the pyroglutaminol 70 <2001J(P1)2997>. 

Work-up with short pad sihca gel chromatography and purification using silica gel pretreated with triethylamine were required to avoid decomposition of epoxides, freshly distilled substrate was required. 

Note In the case of substrates with electron donating groups on aromatic rings or with a furan ring, the use of silica gel pretreated with triethylamine is required to prevent decomposition of products. 

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