Amines, migration

In the first reaction, the amine migrates from the primary to the secondary position in the other from secondary to primary. Both go through very similar aziridinium intermediates, so the difference must be due to the regioselectivity with which this aziridinium opens in each case. 

Lawson (1994) examined levels of aromatic amine migration from a number of laminate samples. Specially prepared laminate pouches containing distilled water were boiled for one hour and tested for primary aromatic amine (PAA) migration using a diazotisation procedure. Olive oil migration data at the same temperature was also obtained. Results are shown in Table 16.5 (detection limit 0.3 t,g dm ). These results, if expressed using the conventional surface area to volume ratio of 6 dm per kg of food, would range between 3 and... 

Table 16.5 Aromatic amine migration from polyurethane adhesives (Lawson 1994)...

In addition to examining aromatic amine migration from Samples 1 and 2 using the colorimetric procedure, two-hour pouch extracts at 70 °C were also examined by GC-MS. Water and 3% acetic acid test solutions from pouch tests undertaken three days after lamination were examined by GC-MS. The pH of 50 ml of test solutions was adjusted to alkaline by adding 0.1 molar sodium hydroxide solution. Resulting solutions were shaken with 5 ml of dichloromethane in a separating funnel and the layers allowed to separate. The dichloromethane layer was then transferred to a GC-MS vial and examined by GC-MS under the following conditions. 

For those products laminated using reactive polyurethane based adhesives, suppliers have been aware for many years of the potential migration of amines formed by the reaction of unreacted isocyanate monomer with water and recommend that laminated products are given time to fully cure before they are used in contact with food. Adhesives have been developed that contain low levels of monomeric aromatic isocyanates, in order to reduce any potential migration of aromatic amines into food in critical applications. Such adhesives are not considered to present any notable amine migration hazard unless used in high-temperature applications. 

Reaction Mechanism. Electron micrographs of the face of FT-30 membrane show an unusual appearance. Unlike other interfacially formed membranes such as the NS-lOO which appear smooth and featureless in electron micrographs, the FT-30 has a rough surface with protuberances coming out of the plane of the membrane (Figure 3). This appearance of FT-30 seems to be related to the mechanism of the interfacial reaction. As stated previously, Morgan presented evidence that the reaction takes place primarily on the solvent side of the interface that is, the amine migrates from the water phase to... 

An interesting amine migration followed by a Claisen rearrangement occurs on heating the condensation product of 2-methyl-3-propyn-2-ol with dimethylaceta-mide diethylacetal (Scheme 41). Acid hydrolysis of the products leads to a 4-oxohexanoate. 

TLC analyses of acid ethoxylate, amine ethoxylate, and amine oxide surfactants are summarized in Tables 14—16. Tertiary amine may be separated from amine oxide by TLC on sihca or alumina. The amine oxide remains near the start line, while the amine migrates up the plate. Modified Dragendorlf reagent is suitable for detection, as are a number of other visualizers. 

In the reaction of aryl and alkenyl halides with 1,3-pentadiene (248), amine and alcohol capture the 7r-allylpalladium intermediate to form 249. In the reactions of o-iodoaniline (250) and o-iodobenzyl alcohol (253) with 1,3-dienes, the amine and benzyl alcohol capture the Tr-allylpalladium intermediates 251 and 254 to give 252 and 255[173-175]. The reaction of o-iodoaniline (250) with 1,4-pen tadiene (256) affords the cyclized product 260 via arylpalladiuni formation, addition to the diene 256 to form 257. palladium migration (elimination of Pd—H and readdition to give 258) to form the Tr-allylpalladium 259, and intramolecular displacement of Tr-allylpalladium with the amine to form 260[176], o-Iodophenol reacts similarly. 

Hydroperoxides have been obtained from the autoxidation of alkanes, aralkanes, alkenes, ketones, enols, hydrazones, aromatic amines, amides, ethers, acetals, alcohols, and organomineral compounds, eg, Grignard reagents (10,45). In autoxidations involving hydrazones, double-bond migration occurs with the formation of hydroperoxy—azo compounds via free-radical chain processes (10,59) (eq. 20). 

Bake sulfonation is an important variant of the normal sulfonation procedure. The reaction is restricted to aromatic amines, the sulfate salts of which ate prepared and heated (dry) at a temperature of approximately 200°C in vacuo. The sulfonic acid group migrates to the ortho or para positions of the amine to give a mixture of orthanilic acid [88-21-1] and sulfanilic acid [121 -57-3] respectively. This tendency is also apparent in polynuclear systems so that 1-naphthylamine gives 1-naphthy1amine-4-su1fonic acid. 

The mechanism of the reaction is unknown. The stereospecificity observed with (E)- and (Z)-l-methyl-2-phenylethylene points to a one-step reaction. The very low Hammett constant, -0.43, determined with phenylethylenes substituted in the benzene ring, excludes polar intermediates. Yields of only a few percent are obtained in the reaction of aliphatic alkenes with (52). In the reaction of cyclohexene with (52), further amination of the aziridine to aminoaziridine (99) is observed. Instead of diphenylazirine, diphenylacetonitrile (100) is formed from diphenylacetylene by NH uptake from (52) and phenyl migration. 

Rearrangement of an enamine to a Sehiff s base through N- to C-alkyl migration was reported 729). These authors also found that enamines, rather than aminals, were formed from butyraldehyde and seeondary amines (730). Chloramines and aeetylenes reacted to give chloroenamine intermediates, which hydrolyzed on work-up of the reactions (731). 

In the Lossen reaction a hydroxamic acid derivative (usually an 0-acyl derivative) is deprotonated by base, and rearranges via migration of the group R to give an isocyanate 2. Under the usual reaction conditions—i.e. aqueous alkaline solution—the isocyanate reacts further to yield the amine 3. The Lossen reaction is closely related to the Hofmann rearrangement and the Curtins reaction. 

Tertiary amines from quaternary ammonium salts by migration of an alkyl group... 

Following the radical pathway" the next step is a homolytical cleavage of the N-R bond. The rearrangement to yield the tertiary amine 3 then proceeds via an intermediate radical-pair 4a. The order of migration is propargyl > allyl > benzyl > alkyl ... 

Incorporation of extensive branching in the side chain similarly does not decrease pharmacologic activity. Reductive alkylation of aminoalcohol, 42, with isobutyraldehyde affords the amine, 43. Acylation of the amine with benzoyl chloride probably goes initially to the amide (44). The acid catalysis used in the reaction leads to an N to 0 acyl migration to afford iso-bucaine (45). ... 

In an analogous sequence, reductive alkylation of aminoalcohol, 46, with cyclohexanone affords the secondary amine (47). Acylation with benzoyl chloride affords hexylcaine (48) in a reaction that may again involve acyl migration. 

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