Primary and Secondary Aliphatic Amines

Primary and secondary aliphatic amines react relatively rapidly with epoxy groups at room or lower temperature to form three-dimensional crosslinked structures. The resulting cured epoxies have relatively high moisture resistance and good chemical resistance, particularly to solvents. They also have moderate heat resistance with a heat distortion temperature in the range of 70 to 110°C. Thus, short-term exposures of cured adhesive joints at temperatures up to 100°C can generally be tolerated. 

These aliphatic amines can also be cured at elevated temperatures to provide a more densely crosslinked structure with better mechanical properties, elevated-temperature performance, and chemical resistance. Table 5.3 illustrates the effect of curing temperature on the bond strength of DGEB A epoxy with two different aliphatic amines. 

FIGURE 5.1 Common polyamines for curing epoxy resins.5 

Other amines, such as aromatic or cycloaliphatic, are less reactive and generally require elevated-temperature cures that result in higher heat distortion temperatures (140 to 150°C). However, aromatic amine adducts of liquid epoxies can be accelerated to cure at room temperature. Aliphatic amines can also be accelerated. 

Epoxy resin formulations containing aliphatic amines will blush and provide an oily surface under very humid conditions. This is due to a reaction of the amine primary hydrogen atoms with carbon dioxide. Resistance to blushing is more important for coatings than for 

Entry Loaded resin Cleavage conditions Product, yield (purity) Ref. 

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Crysialline Derivatives of Primary and Secondary Aliphatic Amines... 

The melting points of the derivatives of some primary and secondary aliphatic amines are collected in Table 111,123. 

The most versatile derivative from which the free base can be readily recovered is the picrate. This is very satisfactory for primary and secondary aliphatic amines and aromatic amines and is particularly so for heterocyclic bases. The amine, dissolv in water or alcohol, is treated with excess of a saturated solution of picric acid in water or alcohol, respectively, until separation of the picrate is complete. If separation does not occur, the solution is stirred vigorously and warmed for a few minutes, or diluted with a solvent in which the picrate is insoluble. Thus, a solution of the amine and picric acid in ethanol can be treated with petroleum ether to precipitate the picrate. Alternatively, the amine can be dissolved in alcohol and aqueous picric acid added. The picrate is filtered off, washed with water or ethanol and recrystallised from boiling water, ethanol, methanol, aqueous ethanol, methanol or chloroform. The solubility of picric acid in water and ethanol is 1.4 and 6.23 % respectively at 20°. 

Dehydrofluorination by primary and secondary aliphatic amines occurs at room temperature and is the basis of diamine cross linkmg, which occurs by dehydrofluonnation and subsequent nucleophihc substitution of the double bond The locus of dehydrofluonnation is a VDF unit flanked by two perfluoroolefin units This selectively base-sensitive methylene group also undergoes elimination as the first step in phase-transfer-catalyzed cross-hnking with quaternary ammo mum or phosphomum salts, bisphenols, and morganic oxides and hydroxides as HF acceptors [31, 32]... 

These Br nsted-type plots often seem to be scatter diagrams until the points are collated into groups related by specific structural features. Thus, p-nitrophenyl acetate gives four separate, but parallel, lines for reactions with pyridines, anilines, imidazoles, and oxygen nucleophiles.Figure 7-4 shows such a plot for the reaction of trans-cmmm c anhydride with primary and secondary aliphatic amines to give substituted cinnamamides.All of the primary amines without substituents on the a carbon (R-CHi-NHi) fall on a line of slope 0.62 cyclopentylamine also lies on this line. If this line is characteristic of normal behavior, most of the deviations become qualitatively explicable. The line drawn through the secondary amines (slope 1.98) connects amines with the structure R-CHi-NH-CHi-R. The different steric requirements in the acylation reaction and in the model process... 

Primary and secondary aliphatic amines, morpholine and 2-methylaziridine and aniline and even the sterically hindered 2.2,6,6-tetramethylpiperidine readily react with 6-bromo-trithiadiazepine 7, in certain cases in the presence of /V./V-diisopropylethylamine, at room temperature by substitution of the bromine atom ammonia, for example, yields trithiadiazepin-6-amine 22 (R1 = R2 = H). There is compelling evidence that these reactions proceed by an elimination-addition mechanism via the heteroaryne, trithiadiazepyne 21.391... 

Ethyleneimine reacts with (p-tolylsulfonyl)acetylene to give only the (Z)-product 115 via trans addition (equation 91), while primary and secondary aliphatic amines afford ( )-products76. With nonterminal acetylenes such as l-(ethylsulfonyl)-l-propyne, the reactions of ethyleneimine, n-propylamine and f-butylamine give mixtures of ( )- and (Z)-adducts. The double conjugate addition of sodium sulfide, selenide and telluride to bis(l-propynyl)sulfone (116) produces heterocycles (117) as illustrated in equation 9277. 

Baum AA, Kamischky LA, McLeod Jr D, Kasai PH (1973) Mercury photo-sensitized oxidation of primary and secondary aliphatic amines J Am Chem Soc 95(2) 617-618... 

Nitroxyl radicals (AmO ) are known to react rapidly with alkyl radicals and efficiently retard the radical polymerization of hydrocarbons [7]. At the same time, only aromatic nitroxyls are capable of reacting with alkylperoxyl radicals [10,39] and in this case the chain termination in the oxidation of saturated hydrocarbons occurs stoichiometrically. However, in the processes of oxidation of alcohols, alkenes, and primary and secondary aliphatic amines in which the chain reaction involves the HOT, >C(0H)02 , and >C(NHR)02 radicals, possessing the... 

Methyl-1,2,4-triazolo[l,5-a]pyrimidin-7-on forms salts with primary and secondary aliphatic amines (61JOC3834). Rather soluble tetrabutylam-monium salts may be convenient for synthesis (91JHC721). Products of synthesis A, formed from 2 mol of AT and 1 mol of acetoacetic ester,... 

Hydroperoxides and peroxides oxidize primary and secondary aliphatic amines to imines. Thus f-butyl hydroperoxide oxidizes 4-methyl-2-pentyl-amine to 2-(4-methylpentylidene)-4-methyl-2-pentylamine in 66% yield [29]. Di-r-butyl peroxide reacts in a similar manner [29]. However, this reaction is... 

Formaldehyde reacts with primary and secondary aliphatic amines but not with tertiary amines. The reactions with methyl and dimethyl amines proceed as follows HCHO + HaN. CH, - H. CH(OH). HN. CHS, HCHO + HN(CHj)a - HCH(OH). N(CHS)S The reaction of formaldehyde with... 

Salts M[Cr03X] (where X = iodate, sulfate, NH2, etc.) have earlier been described.2 Adducts of KCr03X (X = F, Cl, Br, I03) with primary and secondary aliphatic amines have been characterized in solution by their UV and IR spectra.1419... 

Carbon disulphide reacts additively with primary and secondary aliphatic amines to form alkylammonium salts of alkyldithiocarbamic acids. The products obtained with dimethylamine, diethylamine and piperidine, also certain derivatives of these products, are manufactured on a large scale for use as accelerators in the vulcanisation of rubber. With aromatic amines the disulphide reacts with elimination of hydrogen sulphide and formation of substituted thio-ureas, e.g. thiocarbanilide. 

Primary and secondary aliphatic amines can be linked to polymeric supports by acid-labile linkers or by linkers sensitive to nucleophiles. Linkers cleavable by light or by transition metal catalysis have also been described. The main types of linker for amines are sketched in Figure 3.24. 

Sulfite ion forms a complex of structure III (Refs 44 80), which is a source of yield loss during the purification of TNT if the pH exceeds 8. Cyanide ion also forms a compd of structure III (Ref 44) the kinetics of this reaction has been studied (Ref 76), TNT, as the anion I, can react with itself to form adducts of type II it can similarly react with 13 >5-trinitrobenzene (Ref 57). Primary and secondary aliphatic amines form a-complexes (Refs 46 58), but tertiary amines (in an aprotic solvent), and aromatic amines, form ir-complexes instead. Upon soln in liq ammonia, a complex of type III is initially formed, with no evidence of I (Ref 105). With time, a second NH2 group becomes attached to the ring carbon with the methyl group this compd has cis- and transisomers. Removal of the ammonia gave a red... 

The aminolysis of turns-1,2-bis(ethylsulfonyl)-1.2-dichlorocthcnc (336) by primary and secondary aliphatic amines in acetonitrile has been studied.305 Thermolysis in p-xylene solution of 4-azidothiazoles (337) displayed some interesting neighbouring-group effects,306 e.g. in (337) with R1 = Ph, R2 = (acceleration produced in parentheses) NO2 (19-fold), phenyliminomethyl (16-fold), formyl (4.5-fold), and acetyl (2.2-fold). Rate data for nucleophilic attack on phenyldimethylsulfonimn ions by... 

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