Amines Basic character

The unshared pair of electrons on the nitrogen atom provides the basic character to the fatty amines. Basicity of amines has been deterrnined as... 

The basicities of amines, ethers, and carbonyl compounds are invariably decreased by fluonnation. 2,2,2-Tnfluoroethylamine (p f = 3.3 [61]) and C 5NH2 = -0.36 [62]) are about 10 times less basic than CH3CH2NH2 and CgH5NH2, respectively, and (CF3)2CHNH2 (p j, = 1 22 [71]) is over 10 times less basic than 1-C3H2NH2. The relative gas-phase acidities in Table 15 illustrate the large effect of fluonnation. Perfluoro-rerf-amines (R )3N and ethers R Rf have no basic character m solution [, 74], and CF3COCF3 is not protonated by superacids [72]. 

Aromatic amines, containing the amino-group in the side-chain, have the basic character and properties of aliphatic cirrfines. 

Sulplianilic Acid.—The acid characters of this substance, whuh is both base. and acid, are more piominently dereloped than the basic character. Neveithcless it leacts with nitrous aud like a primary amine, and forms a diazoniiim s.alt, which has the follovving constitution (sec Piep. 62, p. 161)... 

In this reaction, one of the products is OH-, which is the species of basic character in aqueous solutions. When NaOH dissolves in water, the reaction is not actually an ionization reaction because the Na+ and OH- ions already exist in the solid. The process is a dissolution process rather than an ionization reaction. Substances such as NaOH, KOH, Ca(OH)2, NH3, and amines (RH2N, R2HN, and R3N) are all bases because their water solutions contain OH-. The compounds dissolve in water to give solutions that conduct an electric current, change the colors of indicators, and neutralize acids,... 

The second chromophore involves another a,g-unsaturated ketone that is in conjugation with an anomalously behaving amide (7). The tertiary amine is responsible for the basic character and the phenolic group is acidic. CTC is fluorescent and can be assayed polarographically (8). 

FIGURE 2.4 It is the density of the lone pair of electrons on nitrogen that determines the basic character of amines. 

The most important and extensively studied pesticides of this group (Fig. 10, Table 3) are Amitrole and several members of the family of s-triazines [89,151, 153,155,156]. Amitrole had been widely used as a herbicide,but its uses as a registered product for application on food crops were canceled starting in 1971 because it was suspected of inducing thyroid tumors in rats [157 -162]. Amitrole is soluble in water, with a weak basic character (PKb = 10) and behaves chemically as a typical aromatic amine. 

Basicity of amines is related to their structure. Basic character of an amine depends upon the ease of formation of the cation by accepting a proton from the acid. The more stable the cation Is relative to the amine, more basic is the amine. 

Further evidence for the relatively weakly basic character of th j aziridme nitrogen atom wae provided by a proton magnetic resonance study of a series of cyolic amines,1 1 and measurements of the basicity of cyclic and branched amines toward the Lewis acid trimethylboron. ... 

Under mild conditions, hydroformylation of olefins with rhodium carbonyl complexes selectively produces aldehydes. A one-step synthesis of oxo alcohols is possible using monomeric or polymeric amines, such as dimethylbenzylamine or anion exchange resin analog to hydrogenate the aldehyde. The rate of aldehyde hydrogenation passes through a maximum as amine basicity and concentration increase. IR data of the reaction reveal that anionic rhodium carbonyl clusters, normally absent, are formed on addition of amine. Aldehyde hydrogenation is attributed to enhanced hydridic character of a Rh-H intermediate via amine coordination to rhodium. 

The existence of the alkylamines was predicted by J. von Liebig,1 1837 in 1849, A. Wurtz obtained the primary alkylamines and in 1851, A. W. Hofmann prepared the primary, secondary, and tertiary alkylamines, and also the alkylammonium bases or the quarternary ammonium bases in which all four atoms of the ammonium group are replaced by the alkyl radicles. The basic character of ammonia is retained by the amines, and since the alkyl radicles are themselves basic, the aliphatic amines are even more basic than ammonia itself. W. Ostwald made an estimate of the basicity of the ethyl ammonias, and found the relative strengths of these bases ... 

The electron rich amine function is a good acceptor for hydrogen bonds. On the other hand, the basic character of the amine causes proton transfer from acidic groups. Both types of interaction occur on the silica surface. Together with the siloxane bond formation, three types of hydroxyl-specific interaction of the aminosilane molecule with the silica surface may be described, for the modification in organic solvent. These are displayed in figure 9.23. 

Alkaloids are a group of nitrogen-containing natural products that occur primarily in higher plants, although they are also found in some fungi, such as mushrooms. The name alkaloid (meaning alkali-like ) is applied because they are amines and thus basic. Their basic character allows them to be readily isolated from their plant source. The plant material is extracted with aqueous acid. This converts the alkaloid to an ammonium cation, which is water soluble. Neutralization of the acidic extract with base causes the alkaloid to precipitate. 

Protophillic H-bond donor solvents solvents such as amides, amines or and other compounds with at least one N—II bond, which may be shared or donated. These solvents also have a highly basic character in the Bronsted sense i.e., they have a likelihood of accepting a free proton or a proton from a proton donor molecule (protophillic). These solvents also show high electron donor and acceptor properties (basic and acidic in the Lewis sense). 

Organic amines behave like monovalent weak bases. Their behaviour can be explained along similar lines as the basic character of ammonia. The general formula of a monoamine is R-NH2 (where R is a monovalent organic radical), showing that one hydrogen of the ammonia is replaced by the radical R. When dissolved in water, amines hydrolyse and dissociate as... 

Basic Character.—The alkyl amines then are analogous to alkyl halides, and we find a corresponding homologous series, e.g.j methyl amine, ethyl amine, propyl amine, etc. They are strongly basic compounds, in fact, they are of especial interest because they are more strongly basic than the ammonia from which they are derived. 

All of the aromatic amines with the exception of tri-phenyl amine, whether primary, secondary or tertiary, are basic and form salts with acids. The basic character of the tertiary aromatic amines varies, however, in degree according to the additional radicals substituted for the amino hydrogen. On this account they react differently toward the alkyl halides. 

What now is the constitution of these diazo compounds The facts thus far considered and which must be explained by an accepted constitutional formula are, (i) Their formation by the action of nitrous acid on a primary- amine, (2) Their conversion into azo, amino azo, hydroxy azo and hydrazine compounds and (3) the basic character of the hydroxy compound, diazo benzene, and the true salt character of the compounds formed with strong acids. 

The simplest use of pervaporation is for the separation and subsequent determination of a single analyte as a result, most reported methods using this technique involve individual determinations. The determination of acetaldehyde in semi-solid and solid food samples is one salient example of single-analyte determinations where pervaporation avoids time-consuming sample preparation steps such as filtration, removal of dyestuffs and turbidity from the Carrez solution, and centrifugation [175]. One other example is the determination of trimethylamine (an objective parameter for fish quality evaluation that correlates well with sensory evaluation) [176]. The method is based on pervaporation of the analyte and monitoring of the colour change in Bromothymol Blue caused by the basic character of the amine the results are consistent with those provided by the official method for trimethylamine. 

The amines possess a basic character, but the basicity is weaker than that of the aliphatic amines, in consequence of the negative nature of the phenyl group. 

---