Pyrolysis amides

Ammonolysis of the diacid chloride, obtained from the treatment of C,C -neocarboranecarboxylic acid with phosphorus pentachloride, gives the diacid amide. Pyrolysis of the latter compound does not result in the formation of a cyclic imide, as is observed in the corresponding 1,2-C2B 1 qH 12 derivative (Section III, C, 6) (335). A number of silyl derivatives have been prepared from dilithioneocarborane, and again, in contrast to the isomeric silylcarboranes (Section III, C, 8), they do not tend to form exocyclic derivatives (353). These observations are consistent with the 1,7-arrangement of the carbons in the neocarborane icosahedron. 

A/-Vinylamides and /V-vinylimides can be prepared by reaction of amides and imides with acetjiene (3), by dehydration of hydroxyethyl derivatives (4), by pyrolysis of ethyUdenebisamides (5), or by vinyl exchange (6), among other methods the monomers are stable when properly stored. 

Iminoboianes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)halobotanes as shown in equation 21. Bulky alkah-metal amides, MNR, have been utilized successfully as the strong base,, in such a reaction scheme. Use of hthium-/i /f-butyl(ttimethylsilyl)amide yields an amine, DH, which is relatively volatile (76,79). 

Reactions of the carboxyl group include salt and acid chloride formation, esterification, pyrolysis, reduction, and amide, nitrile, and amine formation. Salt formation occurs when the carboxyUc acid reacts with an alkaline substance (22)... 

The isomerization of oxaziridines (1) to acid amides with migration of a substituent from C to N is a general reaction and is always observed when no other reactions predominate under the relatively harsh conditions (heating to above 150 °C or photolysis). Even then one can make acid amide formation the main reaction by working at 300 °C (57JA5739) and by dilution techniques. For example, caprolactam (63) is formed in 88% yield by flash pyrolysis of oxaziridine (52) at about 300 °C, whereas decomposition of (52) at lower temperatures gives almost no (63) (77JPR274). 

Nonvolatile compounds cannot be analysed unless pyrolysis or derivatisation converts them to a condition amenable to GC. Derivatisation GC (or LC) has been used for several components such as erucamide (imidi-sation for volatility), fatty amines (aromatic amidation for UV detectability), and polyethylene oxides (esterification for both volatility and detectability) [178]. The surface concentration of erucamide on extruded LLDPE films was determined quantitatively by surface washings with ether, followed by evaporation, dissolution... 

Diphenylcyclopropane has been prepared in 24% yield by the Simmons-Smith reaction,2 in 78% yield by treatment of 3,3-diphenylpropyltrimethylammonium iodide with sodium or potassium amide,3 in 61% yield by reaction of 1,1-diphenyl-ethylene with dimethylsulfonium methylide,4 and in unspecified yields from 1,1-diphenylethylene by reaction with diazomethane followed by pyrolysis of the resulting pyrazoline or by reaction with ethyl diazoacetate followed by distillation of the corresponding acid over calcium oxide.5... 

The first total synthesis of D/E-trans annellated yohimbines, e.g., ( )-yohim-bine (74) and ( )-pseudoyohimbine (88), was published in preliminary form by van Tamelen and co-workers (218) in 1958, while full details (219) appeared only in 1969. Key building block 393, prepared from butadiene and p-quinone, was condensed with tryptamine, yielding unsaturated amide 394, which was subsequently transformed to dialdehyde derivative 396. Cyclization of the latter resulted in pseudoyohimbane 397. Final substitution of ring E was achieved via pyrolysis, oxidation, and esterification steps. As a result of the reaction sequence, ( )-pseudoyohimbine was obtained, from which ( )-yohimbine could be prepared via C-3 epimerization. 

As to the origins of the major N compounds identified, it is possible that at least a portion of some of these compounds are pyrolysis products of amino acids, peptides, proteins, [18] and porphyrins (a component of chlorophyll), [19] or originate from the microbial decomposition of plant lignins and other phenolics in the presence of ammonia. [20] Of considerable interest are the identifications aromatic and aliphatic nitriles. Nitriles can be formed from amines with the loss of 2 H2, from amides with the loss of H20, and also by reacting n-alkanoic acid with NH3. [21] The detection of long-chain alkyl- and dialkyl-nitriles points to the presence in the soil or SOM of long-chain amines... 

Oxaziranes are in a real sense active oxygen compounds and exhibit many reactions grossly analogous to those of organic peroxides. Thus they undergo one electron transfer reaction with ferrous salts and on pyrolysis they are converted to amides. Oxaziranes are also useful synthetic intermediates since in appropriate cases they may be isomerized to aromatic nitrones which are a convenient source of N-alkylhydroxylamines. The reaction of oxaziranes with peracids also provides a source of nitrosoal-kanes and is in many instances the method of choice for preparation of these compounds. ... 

A growing specialty application for acrylonitrile is in the manufacture of carbon fibres. These are produced by pyrolysis of oriented polyacrylonitrile fibres and are used to reinforce composites for high-performance applications in the aircraft, defence and aerospace industries. Other minor specialty applications of acrylonitrile are in the production of fatty amines, ion exchange resins and fatty amine amides used in cosmetics, adhesives, corrosion inhibitors and water-treatment resins (Brazdil, 1991). 

Amide reduction with lithium aluminum hydride, 39, 19 Amine oxide formation, 39, 40 Amine oxide pyrolysis, 39, 41, 42 -Aminoacetanilide, 39, 1 Amino adds, synthesis of, 30, 7 2-Amino-4-anilino-6-(chloro-METHYl) -S-TRIAZINE, 38, 1 -Aminobenzaldehyde, 31, 6 hydrazone, 31, 7 oxime, 31, 7 phenylhydrazone, 31, 7 > -Aminobenzoic add, 36, 95 2-Aminobenzophenone, 32, 8 c-Aminocaproic acid, 32, 13 6-Aminocaproic acid hydrochloride,... 

The behavior of various alkyloxaairanee at elevated temperatures under pyrolysis conditions has also been, studied. Under these conditions amides generally are obtained in good yield. These reactions are carried out in the gas phase at 200-300° and are a direct consequence of the relatively weak oxygen-nitrogen bond. Whether unpairing of the electrons of this bond occurs is uncertain but the reaction may best be described as a concerted rearrangement as indicated below ... 

Another drawback of the TEA (both in the GC and HPLC modes) is that A-nitrosamides give extremely poor yields ( 1%) of NO upon pyrolysis. When heated, these compounds, instead of splitting into NO and the parent amides, rearrange to yield diazoalkenes and nitrogen. Recently reported modifications of the TEA have somewhat improved this deficiency in the GC mode, but the corresponding improvements in the HPLC mode are yet to be worked out (78). 

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