Tertiary amines, reactions table

In contrast, tertiary amine catalysts (Table 9) mainly accelerate the water-isocyanate reaction, that is, the gas-generation reaction, but are also catalysts for the hydroxyl-isocyanate reaction. 

Thioxanthones (Table 11) in conjunction with tertiary amines are efficient photoinitiators [140] with absorption characteristics that compare favorably with benzophenones absorption maxima are in the range between 380 and 420 nm (e = lO L moP cm ), depending on the substitution pattern. The reaction mechanism has been extensively investigated by spectroscopic and laser flash photolysis techniques [64,141-143]. It was found that in conjunction with tertiary amines, reactions similar to that of benzophenone-amine systems take place. 

Calorimetry has been used to measure the rate of reaction for several tertiary amines with benzoyl peroxide [48]. The relative rate results are in line with the predictions from general organic chemistry. The rates given in Table 4, see also Scheme 7, are based on A/,A/-dimethylaniline = 1.00. 

The activation energy of substitution of an unactivated aromatic halide (e.g., fiuorobenzene and 2-chloronaphthalene ) is over 30 kcal while that of activated compounds is 5-20 kcal. For the tabulated reactions (Tables II-VIII) with alkoxide and with primary, secondary, or tertiary amines, resonance activation (cf. 278 and 279) by ortho or para nitrogens is found to be greater than inductive activation (cf. 251). This relation is qualitatively demonstrated in... 

For larger cryptands [6] (Cox et al., 1978), the protonation/deprotonation kinetics have also been measured. Table 4 lists the kinetic and the equilibrium data for such cryptands. When compared to the neutralization of protonated tertiary amines by OH, the reaction of the second smallest protonated cryptand [2.1.1] H is 10 to 10 times slower (Cox et al., 1978), indicating a strong shielding and possibly an i -orientation of the proton. For the [2.2.1] cryptand, no k and k-i values could be calculated, probably due to a fast pre-equilibrium between in,in- and m,OMt-conformations. 

Suitable reagents for derivatizing specific functional groups are summarized in Table 8.21. Many of the reactions and reagents are the familiar ones used in qualitative analysis for the characterization of organic compounds by physical means. Alcohols are converted to esters by reaction with an acid chloride in the presence of a base catalyst (e.g., pyridine, tertiary amine, etc). If the alcohol is to be recovered after the separation, then a derivative which is fairly easy to hydrolyze, such as p-nltrophenylcarbonate, is convenient. If the sample contains labile groups, phenylurethane derivatives can be prepared under very mild reaction conditions. Alcohols in aqueous solution can be derivatized with 3,5-dinitrobenzoyl chloride. 

In one approach to catalytic synthesis of 1,2,3-triazoles, copper(l) is introduced to the reaction mixture as Cul. Compounds 1109-1115 are obtained this way. As can be seen in Table 12, a tertiary amine is often added as a base. The reaction conditions are mild and yields of the products are high. In some cases, the reaction can be carried out in water (compound 1115). For the synthesis of triazole 1116, addition of Cu powder is enough to generate catalytic amounts of Cu(l). 

Cyclic chain termination with aromatic amines also occurs in the oxidation of tertiary aliphatic amines (see Table 16.1). To explain this fact, a mechanism of the conversion of the aminyl radical into AmH involving the (3-C—H bonds was suggested [30]. However, its realization is hampered because this reaction due to high triplet repulsion should have high activation energy and low rate constant. Since tertiary amines have low ionization potentials and readily participate in electron transfer reactions, the cyclic mechanism in systems of this type is realized apparently as a sequence of such reactions, similar to that occurring in the systems containing transition metal complexes (see below). 

Angelici and Brink (40) have found that in the reactions of amine with trans-M(CO),(PPhMe2)2+ (M = Mn or Re), the rate of carbamoyl formation follows the order, n-butylamine > cyclohexyl-amine >, isopropylamine > sec-butylamine >> tert-butylamine, implying a strong steric effect in carbamoyl formation. A similar order has been observed in the rate of reaction of organic esters with amines to form amides (41). The data in Table III indicate that a steric effect may be operative in the Ru (CO) /NR3-catalyzed WGSR, since with tertiary amines the rate follows the order, NMeQ > MeNC.H > NEt > NBu0, which does not reflect the basicity of these amines. 

In summary, the reaction of osmium tetroxide with alkenes is a reliable and selective transformation. Chiral diamines and cinchona alkakoid are most frequently used as chiral auxiliaries. Complexes derived from osmium tetroxide with diamines do not undergo catalytic turnover, whereas dihydroquinidine and dihydroquinine derivatives have been found to be very effective catalysts for the oxidation of a variety of alkenes. OsC>4 can be used catalytically in the presence of a secondary oxygen donor (e.g., H202, TBHP, A -methylmorpholine-/V-oxide, sodium periodate, 02, sodium hypochlorite, potassium ferricyanide). Furthermore, a remarkable rate enhancement occurs with the addition of a nucleophilic ligand such as pyridine or a tertiary amine. Table 4-11 lists the preferred chiral ligands for the dihydroxylation of a variety of olefins.61 Table 4-12 lists the recommended ligands for each class of olefins. 

Variations on this procedure are set out in Table IV. It can be seen that adding excess reagents does not Improve the capacity obtained, but that sequential addition is of some benefit (M3, M4). Strong base resins cannot be prepared by this route since tertiary amines do not react (M5), and a very weak secondary amine also gives very little reaction (M6). 

Photolysis or thermolysis of heteroatom-substituted chromium carbene complexes can lead to the formation of ketene-like intermediates (cf. Sections 2.2.3 and 2.2.5). The reaction of these intermediates with tertiary amines can yield ammonium ylides, which can undergo Stevens rearrangement [294,365,366] (see also Entry 6, Table 2.14 and Experimental Procedure 2.2.1). This reaction sequence has been used to prepare pyrrolidones and other nitrogen-containing heterocycles. Examples of such reactions are given in Figure 2.31 and Table 2.21. 

For comparison, fluorous-phase-soluble Pd complexes are only 74-98% selective towards the trans product [168-170]. The isolated yields of the product approached 70% when a threefold excess of olefin to iodobenzene was used (Table 3) however, the percent yield decreased with the use of bromobenzene as expected since activation of bromine-carbon bonds is less favorable than iodo-carbon bonds. It was also possible to catalyze the reaction in the absence of additional triethylamine base (Table 3). In this case, the tertiary amines of the den-drimer most likely act as the base. The catalysts, in general, were fully recover-... 

Silyl alkyl and silyl aryl peroxides 7 are prepared by reaction of alkyl, aryl or aralkyl hydroperoxides with halosilanes (equation 12). Such reactions are carried out in an inert solvent in the presence of an acid acceptor, such as pyridine, ammonia or a tertiary amine in ether or petroleum ether (Table 3) . ... 

Nearly all peptide-bond-forming reactions employ tertiary amines in some manner, most commonly for neutralization of amine salts and/or as an adjunct to the activating agent. Table 2 shows the effect of tertiary amine structure on the rate of racemization of two UNCAs in toluene solvent. 

The parameters that control epimerization in a peptide-bond-forming reaction can be assessed in terms of their thermodynamic and kinetic components. Thermodynamic effects are those that stabilize the deprotonated activated intermediate or the protonated tertiary amine. Kinetic effects are expressed based on the degree of steric hindrance between the tertiary amine and activated intermediate. Table 4 summarizes these contributions and shows examples of high, moderate, and low propensities for contribution to the intrinsic rate of racemization among the various parameters. 

Since nicotine is the major precursor to NNN in tobacco and tobacco smoke, the reaction of nicotine with sodium nitrite was studied to provide information on formation of other tobacco specific nitrosamines, especially NNK and NNA, which could arise by oxidative cleavage of the l -2 bonds or l -5 bond of nicotine followed by nitrosation (26). The reaction was investigated under a variety of conditions as summarized in Table I. All three nitrosamines were formed when the reaction was done under relatively mild conditions (17 hrs, 20 ). The yields are typical of the formation of nitrosamines from tertiary amines (27). At 90 , with a five fold excess of nitrite, only NNN and NNK were detected. Under these conditions, both NNK and NNA gave secondary products. NNK was nitrosated a to the carbonyl to yield 4-(N-methyl-N-nitrosamino)-2-oximino-l-(3-pyridyl)-1-butanone while NNA underwent cyclization followed by oxidation, decarboxylation and dehydration to give l-methyl-5-(3-pyridyl)pyrazole, as shown in Figure 4. Extensive fragmentation and oxidation of the pyrrolidine ring was also observed under these conditions. The products of the reaction of nicotine and nitrite at 90 are summarized in Table II. 

In Table 1 is a list of the environmental secondary and tertiary amines which have been tested by feeding to rats together with nitrite. Of these, several react very readily with nitrite in acid solution, but some, for example phenmetrazine (2 , 27), give rise to a noncarcinogenic N-nitroso derivative. On the other hand, aminopyrine reacts extremely readily with nitrous acid, although it is a tertiary amine, and forms the potent carcinogen nitrosodimethylamine in high yield (28, ). The other amines vary considerably in the extent to which they form N-nitroso derivatives by reaction with nitrous acid, especially at the relatively low concentrations which model human exposure more closely... 

Tertiary amines react with phosgene to give symmetrical tetrasubstituted ureas (Eq. 28). (See Table II.) This reaction probably involves the intermediate... 

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