Amino thermal decomposition

Both urea— and melamine—formaldehyde resins are of low toxicity. In the uncured state, the amino resin contains some free formaldehyde that could be objectionable. However, uncured resins have a very unpleasant taste that would discourage ingestion of more than trace amounts. The molded plastic, or the cured resin on textiles or paper may be considered nontoxic. Combustion or thermal decomposition of the cured resins can evolve toxic gases, such as formaldehyde, hydrogen cyanide, and oxides of nitrogen. 

Reaction of the glycol, 70, affords an oxazolidinone rather than the expected carbamate (71) on fusion with urea. It has been postulated that the urea is in fact the first product formed. This compound then undergoes 0 to N migration with loss of carbon dioxide reaction of the amino alcohol with the isocyanic acid known to result from thermal decomposition of urea affords the observed product, mephenoxolone (74) this compound shows activity quite similar to that of the carbamate. An analogous reaction on the glyceryl ether, 75, affords metaxa-lone (76). 

Photodriven reactions of Fischer carbenes with alcohols produces esters, the expected product from nucleophilic addition to ketenes. Hydroxycarbene complexes, generated in situ by protonation of the corresponding ate complex, produced a-hydroxyesters in modest yield (Table 15) [103]. Ketals,presumably formed by thermal decomposition of the carbenes, were major by-products. The discovery that amides were readily converted to aminocarbene complexes [104] resulted in an efficient approach to a-amino acids by photodriven reaction of these aminocarbenes with alcohols (Table 16) [105,106]. a-Alkylation of the (methyl)(dibenzylamino)carbene complex followed by photolysis produced a range of racemic alanine derivatives (Eq. 26). With chiral oxazolidine carbene complexes optically active amino acid derivatives were available (Eq. 27). Since both enantiomers of the optically active chromium aminocarbene are equally available, both the natural S and unnatural R amino acid derivatives are equally... 

Sulphonic acids are water soluble, viscous liquids. Their acidity is akin to that of sulphuric acid feey form salts with bases but fail to undergo esterification with alcohols. Their properties vary according to the nature of R some are prone to thermal decomposition. They are used as surfactants and in the dye industry some have biological uses. 2-Amino-ethanesulphonic acid is the only naturally occurring sulphonic acid. 

Reacts with vapors of sodium with luminescence at about 260°C. Reacts explosively with thionyl chloride or potassium reacts violently with hexafluoro isopropylidene, amino lithium, ammonia, and strong acids reacts with tert-butyl azidoformate to form explosive carbide reacts with 24-hexadiyn-l, 6-diol to form 2, 4-hexadiyn-l, 6-bischloro-formate, a shock-sensitive compound reacts with isopropyl alcohol to form isopropyl chloroformate and hydrogen chloride thermal decomposition may occur in the presents of iron salts and result in explosion. 

It should be emphasized that citric acid is not the only possible acid employed in Pechini-type syntheses. Other polybasic carboxylic hydroxy acids (malic, tartaric, hydroxyglutaric, etc.) and polybasic carboxylic acids (e.g., succinic) have been probed in Refs. [4, 13-16], As far as amino acids are concerned, glycine seems to remain the only representative [13, 14]. However, the choice of each particular organic acid has never been justified, and no comparative studies are performed in order to find possible dependencies of the process (ability to form a sol, a gel, or a resin, easiness of thermal decomposition of precursors, etc.) on the steric factors, specifically, on the number of hydroxy and carboxylic groups in the molecule of an acid, as well as on the length of its carbon skeleton. 

The thermal decomposition of some 3,5-disubstituted-l,2,4-thiadiazoles has been studied and some nonisothermal kinetic parameters have been reported <1986MI239>. Polarographic measurements of a series of methylated 5-amino-l,2,4-thiadiazoles show that thiadiazoles are not reducible in methanolic lithium chloride solution, while thiadiazolines are uniformily reduced at 0.5 = — 1.6 0.02 V. This technique has been used to assign structures to compounds which may exist theoretically as either thiadiazoles or thiadiazolines <1984CHEC(6)463>. The photoelectron spectrum for 1,2,4-thiadiazole has been published <1996CHEC-II(4)307>. 

The results obtained with this procedure are similar to those previously reported in the literature by Hangartner, Hagenguth et al and Zeman et al (4, 2, 5, 6). The major exception, being the complete lack of alkylated pyrazines and alkylated thiophenes. These odour-intensive compounds arise from the thermal decomposition of proteins and sulphur containing amino acids. They also develop in the thermally induced reaction of proteins with carbohydrates (Maillard reaction). The authors indicated above have demonstrated that these compounds are invariably produced during the thermal treatment of sludge, a process which is not used in this Authority. 

Thermal decomposition of azidoboranes [Eq. (3)], and of [trimethyl-silyl(trimethylsilyloxy)amino]boranes [Eq. (4)], permits a simple synthesis of symmetric iminoboranes RBNR (17-19). A hot tube procedure at about 300°C and 10 Torr turned out to be useful. The iminoborane iPrBNiPr, for example, was prepared at a rate of 10 g/hour by the azidoborane method. No separation problems are met with this method. Handling the liquid reactants of Eqs. (3) and (4) is hazardous. 

The hydrazide of 2,2-diphenyl-3-hydroxypropanoic acid was reduced with lithium aluminum hydride in 7V-ethylmorpholine at 100° to 3-amino-2,2-di-phenylpropanol in 72.5% yield [1145], Much more useful is reduction of N-arenesulfonylhydrazides of acids to aldehydes McFadyen-Stevens reduction) [284, 285] based on an alkali-catalyzed thermal decomposition according to Scheme 174. 

The title phosphonate and related substances undergo thermal decomposition to B-acyl ketenes at temperatures in excess of 50°C. Thus thermolysis in the presence of alcohols, amines, a-hydroxy esters, and a-amino esters affords the corresponding g-keto esters and amides the latter two classes can be cyclized upon subsequent base treatment to unsaturated tetronic and tetramic acids and the related phosphonate reagents. ... 

The reaction of 7-amino-6-carbethoxy-3-cyano-l,4-dimethyl[l,8]naphthyridin-2(17/)-one with piperidine or morpholine does not afford the corresponding substituted [l,8]naphthyridin-2-ones but instead leads to thermal decomposition to give 6-amino-3-cyano-l,4-dimethylpyridin-2(l//)-one (Scheme 6) <2001S103>. 

These examples of explosives show beyond doubt that the m.p. is raised by the introduction of amino group/s. Further, data on thermal decomposition show that the thermal stability is associated with high melting point and low vapor pressure... 

Kinetics of thermal decomposition of explosives 3-amino-5-nitro-l,2,4-triazole (ANTA) and its derivatives [38], l,3-bis(l,2,4-triazol-3-amino)-2,4,6-trinitrobenzene [39] and transition metal salts of NTO [40]. 

Thermal decomposition of 3-arylidenamino- (91) and 3-imidoyl-l,2,3-benzotriazin-4-ones (93) in solution gives 2-aryl- (92) and 2,3-diaryl-quinazolin-4( 177)-ones (94) respectively (80JCS(Pl)633,75S187,75S709). In the latter decomposition phenanthridinones (95) are also formed in minor yields. Mechanisms to account for the isolated products were discussed. 3 -Amino-l,2,3-benzotriazin-4-ones (96) in boiling 1-methylnaphthalene yield in all cases... 

Liquid acids such as HC1 or H2SO4 have been found to be efficient catalysts. However, the catalysts produce intermediate compounds having methylene-amino bonds, such as N-benzyl compound, C6H5N(COOCH3)(CH2C6H5NHCOOCH3) [1], These intermediates do not produce isocyanates and have a harmful influence on the next thermal decomposition step. Since these compounds must be catalytically transformed to desired MDU, the condensation reaction has to be carried out in two steps to use the best characteristics of each catalyst. Solid acid catalysts such as a perfluorinated ion-exchange resin (Nafion) have received limited attention as catalysts for the condensation reaction [2]. 

In 1989, Corriu and workers reported the thermal decomposition (85 °C) of the silyl formate 6, having a remote stabilizing amino group, which was prepared by the insertion reaction of the corresponding pentacoordinated functional silane 5 with CO2,... 

Fig. 7. Thermal decomposition rate of shell organic matrix (Nautilus pompilius) at 150 °C in the presence of water. Individual amino acids are reported in residues/1000 and total amino acid concentration in pmol/g numbers on the ordinate are residues/1000 and pmol/g, respectively. Graph on the left is hydrolyzed fraction of total shell material after thermal treatment and graph on the right the unhydrolyzed fraction in the water...

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