Amines alicyclic

Deamination of primary amines to rearranged alcohols (via diazonhjm compounds) with ring contraction or enlargement for alicyclic amines... 

Alicyclic amines are used as pesticides, plasticizers, explosives, inhibitors of metal corrosion and sweetening agents as well as having uses in the pharmaceuticals industry. Aniline hydrogenation has been studied in the literature with the main reaction products cyclohexylamine, dicyclohexylamine, A-phenylcyclohexylamine, diphenylamine, ammonia, benzene, cyclohexane, cyclohexanol and cyclohexanone [1-9], The products formed depend on the catalyst used, reaction temperature, solvent and whether the reaction is performed in gas or liquid phase. For example high temperature, gas-phase aniline hydrogenation over Rh/Al203 produced cyclohexylamine and dicyclohexylamine as the main products [1],... 

TABLE 2. Structural parameters of the amino group in some alicyclic amines... 

We now turn to the subject of aromatic amines. The number of classes of aromatic species vastly exceeds the number of classes of aliphatic and alicyclic amines. We somewhat arbitrarily consider mixed aromatic/ ali- species such as 7V,7V-dimethylaniline and 7V-methyldiphenylamine as aromatic and so they accompany the totally aromatic triph-enylamine instead of joining the totally ali- species trimethylamine. However more numerous the compounds of potential interest, the number of relevant aromatic species for which there are appropriate thermochemical data is also few. 

The simplest isolable species that fits this description is piperazine (27) with an enthalpy of formation44 of 29.4 kJ mol-1. Can we reliably estimate this value in terms of the conceptually simpler acyclic amines, acyclic polyamines, alicyclic amines or other heterocycles One may estimate it simply as the sum of the enthalpy of formation of cyclohexane (2, n = 6) and twice the exchange energy, S5. The predicted value is 21 kJmol-1, suggestive of at least 7 kJmol-1 of strain. Do not forget that 27 should enjoy stabilization as befits its being a vie-diamine. This destabilization is twice that of piperidine (3, n = 6) as relatedly defined by its measured enthalpy of formation and that estimated by summing the enthalpy of formation of cyclohexane and 1 -85. Equivalently, disproportionation reaction 30 is found to be thermoneutral. 

Good yields of secondary amines are achieved using both the methods in the reactions of aromatic and aliphatic aldehydes as well as of diaUcyl ketones and cycloalkanones with aliphatic and alicyclic amines (and ammonia). Anilines give low yields, but when 2 equiv is used in the sodium hydrogen telluride method, the yields are improved. In the reaction of ammonia with aldehydes, symmetrical secondary amines are obtained, whereas glu-taraldehyde and amines lead to N-substituted piperidines. 

Beard RR, Noe JT Aliphatic and alicyclic amines. In Clayton GD, Clayton FE (eds) Patty s Industrial Hygiene and Toxicology, 3rd ed, rev, Vol 2B, Toxicology, pp 3135-3155. New York, Wiley-Intersdence, 1981... 

Sutton WL Aliphatic and alicyclic amines. In Fassett DW, Irish DD (eds) Industrial Hygiene and Toxicology, 2nd ed, Vol. 2, Toxicology, p 2045. New York, Interscience, 1963... 

Compounds with a terminal triple bond can undergo a Mannich condensation with formaldehyde and secondary aliphatic or alicyclic amines [193],... 

In the aliphatic series, the peracid oxidation appears to be limited to i-alkyl primary amines or alicyclic amines [39]. 

Oxidative Reactions at Nitrogen 1.09.2.2.1 Secondary alicyclic amines... 

Secondary alicyclic amines, such as pyrrolidine and piperidine, have many properties typical of the corresponding aliphatic amines. Metabolic oxidation at secondary alicyclic nitrogens results in the formation of hydroxylamines, which may then undergo enzymic or non-enzymic conversion to nitrones, and in some cases to nitroxide radicals. For example, the 2-substituted piperidino derivative (- )-anabasine (1), a tobacco alkaloid, is metabolized initially to a hydroxylamine (2) and then to the nitrone (3), when incubated with liver and... 

Hydroxylamines formed as metabolites of secondary alicyclic amines may also be converted to nitroxide radicals. For example, the sterically hindered 2,2,6,6-tetramethylpiperidine... 

The relative reactivity of secondary and primary amines with epoxide, k2/kt, can affect the overall kinetics. If k2/kj is not close to 0.5 the parameter f in Eqs. (4-7) and (4-13) becomes significant. In this respect there are differences between aliphatic and aromatic or alicyclic amines. For the aliphatic amines the ratio k2/kj is reported to be in the range 0.6-0.7 83 90), whereas for aromatic amines values in the range 0.2 to 0.5 have been observed 90 9S). For the reaction of BADGE with DDS, Dobas et al. 94) reported a value of 0.21 for k2/k, at 80 °C. This factor is likely to account for part of the observed non-linearity in reduced rate plots at higher levels of conversion. 

Table 4 Solvent effects on intrinsic rate constants for the deprotonation of C-H acids by secondary alicyclic amines and carboxylate ions at 20°C... 

Table 8 Acidities of Fischer carbene complexes and intrinsic rate constants for their deprotonation by secondary alicyclic amines, primary aliphatic amines and hydroxide ion in 50% MeCN-50% water (v/v) at 25°C... 

A further example of an imbalance reduction is seen in the reaction 1-benzyl-l-methoxy-2-nitroethylenes (47-Z) with secondary alicyclic amines in 50% DMSO-50% water (v/v).103... 

Steric effects reduce rate and equilibrium constants of nucleophilic additions but the question how the intrinsic barrier is affected does not always have a clear answer. Comparisons of intrinsic rate constants for the addition of secondary alicyclic amines versus primary aliphatic amines suggest that k0 is reduced by the F-strain. This implies that the development of the F-strain at the transition state is quite far advanced relative to bond formation. The effects of other types of steric hindrance on k0 such as prevention of coplanarity of Y in the adduct or even prevention of jt-overlap between Y and the C=C double bond in the alkene have not been thoroughly examined and hence are less well understood. 

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