Amines chemical properties

Chemical Properties. A combination of excellent chemical and mechanical properties at elevated temperatures result in high performance service in the chemical processing industry. Teflon PEA resins have been exposed to a variety of organic and inorganic compounds commonly encountered in chemical service (26). They are not attacked by inorganic acids, bases, halogens, metal salt solutions, organic acids, and anhydrides. Aromatic and ahphatic hydrocarbons, alcohols, aldehydes, ketones, ethers, amines, esters, chlorinated compounds, and other polymer solvents have Httle effect. However, like other perfluorinated polymers,they react with alkah metals and elemental fluorine. 

Chemical Properties. The chemical reactivity of nylon is a function of the amide groups and the amine and carboxyl ends. The aHphatic segment of the chain is relatively stable. 

Chemical Properties The formation of salts with acids is the most characteristic reaction of amines. Since the amines are soluble in organic solvents and the salts are usually not soluble, acidic products can be conveniendy separated by the reaction with an amine, the unshared electron pair on the amine nitrogen acting as proton acceptor. Amines are good nucleophiles reactions of amines at the nitrogen atom have as a first step the formation of a bond with the unshared electron pair of nitrogen, eg, reactions with acid anhydrides, haUdes, and esters, with carbon dioxide or carbon disulfide, and with isocyanic or isothiocyanic acid derivatives. 

Chemical Properties. Reactions of quaternaries can be categorized iato three types (169) Hoffman eliminations, displacements, and rearrangements. Thermal decomposition of a quaternary ammonium hydroxide to an alkene, tertiary amine, and water is known as the Hoffman elimination (eq. la) (170). This reaction has not been used extensively to prepare olefins. Some cycHc olefins, however, are best prepared this way (171). Exhaustive methylation, followed by elimination, is known as the Hoffman degradation and is important ia the stmctural determination of unknown amines, especially for alkaloids (qv) (172). 

Polyisobutylene has the chemical properties of a saturated hydrocarbon. The unsaturated end groups undergo reactions typical of a hindered olefin and are used, particularly in the case of low mol wt materials, as a route to modification eg, the introduction of amine groups to produce dispersants for lubricating oils. The in-chain unsaturation in butyl mbber is attacked by atmospheric ozone, and unless protected can lead to cracking of strained vulcanizates. Oxidative degradation, which leads to chain cleavage, is slow, and the polymers are protected by antioxidants (75). 

Two new sections on the protection for indoles, imidazoles, and pyrroles, and protection for the amide — NH are included. They are separated from the regular amines because their chemical properties are sufficienth different to affect the chemistry of protection and deprotection. The Reactivity Charts in Chapter 8 are identical to those in the first edition. The chart number appears beside the name of each protective group when it is first discussed. 

Observable Characteristics - Physical State (as shipped) Liquid Color. Colorless Odor Amine-like. Physical and Chemical Properties - Physical State at 15 T7 and I atm. Liquid Molecular Weight 99 Boiling Point at I atm. 396, 202, 475 Freezing Point 1, -17, 256 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.03 at 25 °C (liquid) Vapor (Gas) Specific Gravity 3.4 Ratio of Speoifio Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Data not available Heat of Combustion -13,(XK), -7,220, -302 Heat of Deoomposition Not pertinent. 

Although pyrrole appears to be both an amine and a conjugated diene, its chemical properties are not consistent with either of these structural features. Unlike most other amines, pyrrole is not basic—the pKa of the pyrrolin-ium ion is 0.4 unlike most other conjugated dienes, pyrrole undergoes electrophilic substitution reactions rather than additions. The reason for both these properties, as noted previously in Section 15.5, is that pyrrole has six 77 electrons and is aromatic. Each of the four carbons contributes one... 

There is much evidence to suggest that carcinogenic N-nitros-amines are metabolised by an oxidative process to produce an alkylating agent (J f2) One potential metabolite is therefore the corresponding N-nitrosamide resulting from 2-electron oxidation at the oc-carbon atom, and, indeed, such compounds appear to induce tumours at the site of application without metabolic activation (3) It follows that the chemical properties of N-nitrosamides are relevant to the etiology of cancer ... 

The Schiff bases being derivatives of aldehydes or ketones and various amines have received considerable attention because of their interesting physical and chemical properties, involvement in biologically important reactions and widespread application of their metal complexes. Increasing interest in optically active Schiff bases is connected with the discovery at the beginning of the 1990s of the so-called Jacobsen catalysts used in several asymmetric reactions showing excellent enantioselectivity. 

The chemical structure of histamine has similarities to the structures of other biogenic amines, but important differences also exist. Chemically, histamine is 2-(4-imidazolyl)ethylamine (Fig. 14-1). The ethylamine backbone is a common feature of many of the amine transmitters (e.g. dopamine, norepinephrine and serotonin). However, the imidazole nucleus, absent from other known transmitters, endows histamine with several distinct chemical properties. Among these is prototypic tautomerism, a property that permits it to exist in two different chemical forms (Fig. 14-1). The tautomeric properties of histamine are thought to be critical in the... 

Synthesis and characterization of well-defined, a,w-terminated difunctional siloxane oligomers are discussed. Detailed procedures on the preparation of primary amine- and hydroxy-terminated oligomers are given. Control of the average molecular weight (Mn) and also the possible variations in the backbone structure and composition are explained. The effect of these variations on the physical, thermal and chemical properties of the resulting materials are discussed. Characterization of these oligomers by FT-IR, NMR and UV spectroscopy, potentiometric titration and DSC are summarized. 

There is a distinct relationship between keto-enol tautomerism and the iminium-enamine interconversion it can be seen from the above scheme that enamines are actually nitrogen analogues of enols. Their chemical properties reflect this relationship. It also leads us to another reason why enamine formation is a property of secondary amines, whereas primary amines give imines with aldehydes and ketones (see Section 7.7.1). Enamines from primary amines would undergo rapid conversion into the more stable imine tautomers (compare enol and keto tautomers) this isomerization cannot occur with enamines from secondary amines, and such enamines are, therefore, stable. 

Illustrative of the results which might be expected in using macro-cyclic compounds to separate cations having similar chemical properties in biological systems is the report of Muller (49) involving removal of 85Sr from rats using the bicyclic amine synthesized by Dietrich et al. 

The chemistry of saturated heterocyclic compounds is characteristic of their functional group. For example, nitrogen compounds are amines, oxygen compounds arc ethers, sulfur compounds are sulfides. Differences in chemical reactivity are observed for three-membered rings, e.g., epoxides, whose enhanced reactivity is driven by the relief of their severe ring strain. This chapter discusses heterocycles that are aromatic and have unique chemical properties. 

The spectroscopic and chemical properties of l,4-diazabicyclo[2.2.2]octane (DAB-CO) are consistent with a strong interaction of the in-phase combination of the non-bonded electron pairs of the nitrogen atoms with the symmetric combination of the C—C a bonds, one consequence of which is that the in-phase combination is the HOMO. The two lowest IPs are 7.6 and 9.7 eV [89]. Compare these to the IPs of trimethyl amine (8.44 eV) and ammonia (10.5 eV) [90]. The relative importance of intramolecular orbital interactions through space and through bonds has been reviewed by Hoffmann [6]. 

Copolymers of methacrylic add and ethylene termed as ethylene ionomers have been used as the base polymer for binding alkali, alkaline earth and transition metal ions. Organic amines such as n-hexylamine, hexamethylene tetraamine, 2,2,6,6-tetramethyM-hydroxy piperazine, ethylene diamine and polymeric diamines such as silicone diamine, polyether diamine and polymeric diamines such as silicone diamine, polyether diamine and polyamide oligomers considerably enhance the complex formation characteristics of Zn(II) ethylene ionomers thereby enhancing the physico-chemical properties [13]. 

With the exception of 2,5-diaminopyrrole, which exists predominantly in the 2,5-bisiminopyrrolidine form, the C-aminopyrroles possess the structure of normal aromatic amines and this is generally reflected in their chemical properties. The C-aminopyrroles are, however, less basic than one might expect for an aromatic amine and it is evident that 2-aminopyrroles do not form the pyrrolylammonium ions, but are protonated at the 5-position, giving rise to the resonance-stabilized cations, e.g. (475) (68TL4605, 76S51). 

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