Amines selective

Dicyclohexylarnine may be selectively generated by reductive alkylation of cyclohexylamine by cyclohexanone (15). Stated batch reaction conditions are specifically 0.05—2.0% Pd or Pt catalyst, which is reusable, pressures of 400—700 kPa (55—100 psi), and temperatures of 75—100°C to give complete reduction in 4 h. Continuous vapor-phase amination selective to dicyclohexylarnine is claimed for cyclohexanone (16) or mixed cyclohexanone plus cyclohexanol (17) feeds. Conditions are 5—15 s contact time of <1 1 ammonia ketone, - 3 1 hydrogen ketone at 260°C over nickel on kieselguhr. With mixed feed the preferred conditions over a mixed copper chromite plus nickel catalyst are 18-s contact time at 250 °C with ammonia alkyl = 0.6 1 and hydrogen alkyl = 1 1. 

Methylsulfanyl)-37/-l,5-benzodiazepines 11 (vide supra) react with amines by replacement of the methylsulfany group to yield derivatives 12 of 3//-l,5-benzodiazepin-2-amine. Selected examples are given.283... 

Although trace amine-selective receptors had been hypothesized for several decades and trace amine binding sites had been reported earlier, it was only... 

Consequently, amines with high Kb values require lower concentrations than do low Kb materials to raise pH levels. Nevertheless, volatility, DR, thermal stability, and other factors also need to be taken into account. Inevitably, amine selection is a compromise between these various functional properties. 

Volatility This denotes how much of the total amine supplied will be present in the steam and thus available to neutralize the carbon dioxide (also in the steam). In water, a portion of the total amine hydrolyzes to form an ammonium ion and a hydroxyl ion (the dissociation reaction) the balance of the amine (the free-amine portion) is volatile. Clearly, it is important to know the size of this volatile fraction, which depends on the particular amine selected and the pH of the system. In turn, the pH depends on the concentration of total amine originally present so that, the higher the pH, the greater the volatile fraction. 

Moreau and co-workers have also prepared (ll ,2K)-l,2-diaminocyclo-hexane amino-urea and thiourea derivatives [43]. Diphenylethylenediamine-substituted monothioureas are more stable than the cyclohexyldiamine counterpart, but they can also rearrange to guanidine derivatives, especially at high temperature or in the presence of metal [43]. Under the same conditions, thioureas also rearrange to guanidines in the presence of amines. Selective formation of substituted guanidines from thiourea derivatives of diaminocy-clohexane or diphenylethylenediamine were also reported in a recent paper from Ishikawa [44]. 

In an analoguous case, two-phase telomerization of butadiene with ammonia to give octadienylamine has been reported where higher selectivity is realized in a two-phase system of water-toluene. Here, octadienylamine is more reactive than ammonia and consecutive reaction leads to sec and ten amines. By adopting a two-phase strategy, a primary amine selectivity as high as 91 % has been realized (Drieben-Hoscher and Keim, 1998). 

Ricaurte, G.A. Fomo, L.S. Wilson, M.A. DeLanny, L.E. Irwin, I. Molliver, M. and Langston, J.W. ( )3,4-Methylenedioxymethamphet-amine selectively damages central serotonergic neurons in non-human primates. JAMA 260 51-55, 1988. 

T. A. Johnson and D. P. Freyberger, Lithium Hydroxide Modified Sponge Catalysts for Control of Primary Amine Selectivity in Nitrile Hydrogenations, Chemical Industries (Dekker), 82 (Catal. Org. React.), 201-227 (2000). 

Solvent system Conversion 1-octene [%] Amine selectivity [%] n iso TON TOP [h-i] Rh loss [%]... 

Fig. 7.2 Pharmacophore fingerprint distribution for 20 primary amines selected by using the ProSAR strategy, random selection and occupancy optimisation of fingerprint bins, respectively.

Comparing Tables I and II reveals that amine concentration is the second important variable in the aldehyde hydrogenation reaction. For a given amine, selectivity to alcohol passes through a maximum with increasing concentration of N donor. Thus with DMBA, the alcohol present at 80% olefin cvonversion was 5, 29, and 28% at 1, 2, and —3M (resin), respectively, suggesting an optimum DMBA concentration of about 2M. 

The effect of adding Ca or Mn to CuCr/A Oj (TiC ) catalysts presented in Table 2 demonstrate that i) the selectivity in N-dimethyldodecylamine is much enhanced, the effect being rather more significant with alumina than with a titania support ii) the total amine selectivity is particularly high, above 98% instead of 80% without promoter. 

Drug Mechanism (Amine selectivity) Advantages Disadvantages... 

Amines selectively gave the corresponding N-oxides that are only minor impurities in the radical process... 

The DIVSEL program was developed by Pickett et al. for combinatorial reagent selection using three-point pharmacophores as the descriptor for similarity calculations [2], The algorithm starts by selecting the compound most dissimilar to the others in the set and then iteratively selects compounds most dissimilar to those already selected. DIVSEL was used to select a set of carboxylic acids from a collection of 1100 monocarboxylic acids for an amide library, based on the pharmacophoric diversity of the products. Eleven diverse amines were selected based on pharmacophoric diversity. A virtual library of 12100 amides was constructed from the 11 amines and 1100 carboxylic acids. The DIVSEL program used the pharmacophore fingerprints for the product virtual library to select a diverse set of the carboxylic acids. The products of 90 acids with the 11 amines selected with DIVSEL covered 85% of the three-point pharmacophores represented by the entire 12100 compound virtual library. 

Nucleophilic substitution of R2. The n amines selected are dissolved in 15 mL of appropriate solvent. Each amine is in 5 M excess to the amount of amination of the gel. Each aliquot of R]-substituted gel is divided into 5-mL fractions, suspended in the previous mixture, and incubated at 85°C for 72 h. At the end of the synthesis, the gels are washed with appropriate solvent, weighed, and stored at 0-4°C in 20% v/v ethanol (Fig. 3). 

Nitrile Catalyst Medium T(° C) H2 P (MPa) Primary Amine Selectivity (or Yield) (mol%) Secondary Tertiary Other Amine Amine Products Ref. 

L.F. Audrieth, L.H. Eriksen W.R. Tomlinson, Jr, USP 3309251(1967) CA 66, 117568v(1967) (A liq expl consisting of Nitro-methane and 1—20 wt% of an amine selected from the group ethylenediamine, butylamine, and morpholine. Up to 10% of a diluent such as glycerol, EtOH, and Et Cellosolve could... 

Although the hydrogenation of nitrites is generally expected to produce the primary amine, selectivity in the formation of such products is frequently lowered by the production of secondary and tertiary amines. As depicted in Scheme 19.3, these products are formed by the condensation of an imine intermediate (31) with the product amines to give 1,1-diamino species (32 and 33), which are hydrogenolyzed to give the secondary (34) or tertiary amine, 35. 

It has for long been assumed that morpholine is the preferred amine in this reaction, and that other amines generally give inferior results. With the aim of examining the scope of the reaction with regard to amine variation, the reaction was run with a series of amines selected by their principal properties. Acetophenone was used as the ketone substrate in these reactions, and quinoline was used as a solvent. The reason for using quinoline was that it permits a large span of the reaction temperature (b.p 237 ° C). 

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