Aminal exchange

Tertiary amine exchangers possess —R3NH2 groups which have exchanging properties only in an acidic medium when a proton is bound to the nitrogen atom. 

The majority of polyetherimides are tractable and their polymerization can be performed in solution or in the melt. High molecular weight polyetherimides have been synthesized via one-step imide—amine exchange reaction between bis(etherimide)s and diamine (67) according to the following ... 

This carboxyborane can undergo an amine exchange reaction with Hquid ammonia (eq. 7) to yield the boron analogue of glycine, the simplest alpha-amino acid (13). There has been a great deal of work on the pharmacological activity of these amino acid analogues (14). 

The hot lean amine proceeds to the rich/lean amine exchanger and then to additional coolers to lower its temperature to no less than 10°F above the inlet gas temperature. This prevents hydrocarbons from con-... 

Rich/lean amine exchangers are usually shell-and-tube exchangers with the corrosive rich amine flowing through the tubes. The purpose of these exchangers is to reduce the reboiler duty by recovering some of the sensible heat from the lean amine. 

A. l-(l-Cyclopenten-l-yl)piperidine (148) reaeted with N-methyl-3-bromopropylamine hydrobromide to yield 74% of a mixture of enamines (149) 112). The proposed mechanism involved an amine exchange to give the enamine 150 which underwent internal alkylation. 

The Zincke reaction is an overall amine exchange process that converts N- 2,A-dinitrophenyl)pyridinium salts (e.g, 1), known as Zincke salts, to iV-aryl or iV-alkyl pyridiniums 2 upon treatment with the appropriate aniline or alkyl amine. The Zincke salts are produced by reaction of pyridine or its derivatives with 2,4-dinitrochlorobenzene. This venerable reaction, first reported in 1904 and independently explored by Konig, proceeds via nucleophilic addition, ring opening, amine exchange, and electrocyclic reclosure, a sequence that also requires a series of proton transfers. By... 

Dithiobenzoic acid metal complexes, 2, 646 colours, 2, 646 Dithiobiuret metal complexes, 2, 640 Dithiocarbamates chelating resins mineral processing, 6,826 Dithiocarbamic acid metal complexes, 2,585 amine exchange, 1,428 photographic emulsions, 6,98 nickel poisoning, 6,768 tellurium(Il) complexes photothermography, 6,121 Dithiocarbazic acid metal complexes, 2,803 Dithiocarbimic acid metal complexes, 2,588 Dithiocarbimic acid, cyano-metal complexes, 2,808 Dithiocarboxylic acids metal complexes, 2,646 Dithiodiacetic acid metal complexes, 2, 806 Dithiodiketones... 

Vinamidinium salts have been used for the preparation of 2,3- or 2,5-disubstituted pyrroles. Thus, reaction of sarcosine ethyl ester with 18 results in an amine-exchange reaction at the least hindered position. Anion mediated cyclization and elimination of dimethylamine leads to 19 <96T6879>. 

A second method of producing pyrazole-containing compounds was described by Olivera et al. [51] and involves the use of an enaminoketone (41) (Scheme 5). The initial amine-exchange/heterocyclization produced pyrazole tautomers, so another method was attempted with NT NHMe. However, two isomers were produced with the methyl group on either nitrogen. Compound 42 was formed in 55% yield. 

The added primary amine may facilitate the cleavage of the Ti-N bond of the key intermediate 107 through the coordination to the titanium center followed by u-bond metathesis. Such an intramolecular exchange process is expected to be facile. The amine exchange product is 106, which can then be rapidly converted to 105 and the corresponding silylated amine to complete the catalytic cycle. 

The Zincke reaction is an overall amine exchange process that converts N- 2,A-dinitrophenyl)pyridinium salts, known as Zincke salts, to A -aryl or A -alkyl pyridiniums upon treatment with the appropriate aniline or alkyl amine. 

Trimetrexate (88) Is an antineoplastic agent related to the well-established folic acid antimeta-bolite methotrexate. It can be synthesized by selective diazotization of the most basic amino group of 2,4,6-triamino-5-methylquinazoline (85) followed by a Sandmeyer displacement with CuCN to give nitrile 86. Careful reduction asing Raney nickel produces the aminomethyl intermediate 87 or, if the reaction is carried out in the presence of 3,4,5-triniethoxyaniline, trimetrexate (88) [24]. One presumes that that outcome is a consequence of amine exchange at the partially reduced imine stage and further reduction. 

When the 1,2,5-thiadiazole-1,1-dioxide is fused to an aromatic ring, the nucleophilic addition occurs at sulfur not carbon. In these cases, the reduced thiadiazole behaves as a classic sulfamide, readily undergoing amine exchange (Scheme 8) <82JCR(S)84>. 

Reaction of A -acylamino acids with the Vilsmeier-Haack reagent leads to 2-alkyl-4-[(Af,Af-dimethylamino)methylene]-5(47i)-oxazolones 814. The reactivity of these compounds with various nucleophiles has been studied. Primary alkylamines undergo amine exchange with 814 to afford 2-alkyl-4-[(alkylamino)methylene]-5(4/i)-oxazolones 815 (Scheme 7.250). ° ... 

More powerful than the Anderson-Shapiro reagent is the diazaphospholidine reagent developed by Alexakis and co-workers37 39. The reagent is easily prepared by amine exchange of p[N(ch3)2]3 with (R,R) N,A -dimethylcyclohexane-l,2-diamine in refluxing toluene. It must be stored as an 0.2 M solution under nitrogen. The reaction with the analyte alcohol is run in the NMR tube at room temperature. 

Amine-exchange reactions Reaction of l-(l-cyclopenten-l-yl)-piperi-dine with A-methyl-3-bromopropylamine hydrobromide [188]. 

Reactions involving amine exchange of bis-(sali-cylaldimino)copper(ll) compounds and a variety of amines have been reported by other workers. The failure of several /9-ketoimine-copper(ll) compounds to undergo a comparable reaction is reported here. Several examples of the amine exchange of /9-ketoimines in the presence of copper-(II) ion are given. The scope and nature of these reactions are discussed, and the anomalous behavior of /9-ketoimine-copper(ll) compounds is rationalized. 

Amine-Exchange Reactions. Procedure A. A solution of a copper compound was heated in 10 ml. of n-butylamine or aniline on a steam bath, and, after 30 minutes, the mixture was poured into water. The crystals which formed were filtered off and recrystallizea from 95% ethanol. 

CH3(CH3N=)CCHCOCH3]2Cu + CH3(CH2)3NH2. The crude product resulting from attempted amine exchange appears to be impure bis-(4-imino-pentane-2-ono)copper(II) on the basis of analysis. Anal Found C, 44.18 H, 6.16. 

Reaction of Ethylenediamine. Using 0.015 mole of diamine, 0.9 gram (61%) of bisacetylacetoneethylenediiminocopper(II) was obtained. Red platelets, m.p. 138-41° (dilute ethanol). There was no depression of melting point on admixture with authentic sample. Using 0.005 or 0.01 mole of amine, a mixture of blue and gray crystals was obtained, suggesting hydrolysis and, certainly, the absence of amine exchange. 

The failure of several bis- (/ -ketoimine) copper (II) chelates to react with n-butylamine (Table I) is a marked and interesting contrast to the apparently facile reaction of the bis-(salicylaldimine)copper(II) compounds (13, 15, 17). On the other hand, there are some examples of amine exchange, notably the reaction of ethylenediamine with 4-phenyliminopentane-2-one or 4-iminopentane-2-one. That this reaction requires copper ion is indicated by the observation that, if copper ion is omitted, 40 to 60% of the unreacted / -ketoimine is recovered with the rest unavailable, probably because of hydrolysis or mechanical loss. It would be tempting to suggest that the equilibrium... 

Table 1. Summary of Results of Amine-Exchange Reactions Involving fi-Keto- ...

Such a mechanism has been suggested by Verter and Frost (27) to explain the amine-exchange reaction of butylamine and bis-(salicylaldimine) copper (II) chelates. 

A troublesome aspect still to be considered is the observation that salicylanil undergoes amine exchange, though 4-phenyliminopentane-2-one does not. Probably, this is due to the difference in resonance stabilization of the two compounds... 

There are several instances in which it appears that ammonia is involved in amine-exchange. Thus, the failures to prepare bis-(4-methyliminopentane-2-ono)-copper(II) might be attributed to amine exchange ... 

Also, the failure to prepare the copper chelates of bisacetylacetonetrimethylenedi-imine and 4-butyliminopentane-2-one might be attributed to amine exchange, for a similar reason. The conclusion that amine exchange has occurred is reasonable, but there are reasons for doubting that this is the only explanation. 

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