Aniline properties

T)u Pont Aniline Properties, Uses, Storage, and Handling Bulletin, E. I. du Pont de Nemours Co., Inc., 1983. 

In modem techniques the so-called liquid crystals are gaining increasing importance. The liquid crystal state is characterized as being an intermediate between isotropic liquids and anisotropic solids in some temperature interval they preserve some properties of a liquid (e.g., fluidity) and some properties of a crystal (e.g., anisotropy). The liquid crystal state is realized more often in substances whose molecules consist of a long flat atomic structure (rods) with included benzene rings (e.g., 4-met-oksi-benziliden-4 -butil-aniline). Properties of liqnid crystals are defined by different featnres of molecular packing in... 

Concerning non-metallic compounds, the antiknocking properties of nitrogen compounds such that derivatives of aniline, indole and quinoline, and certain phenol derivatives have been mentioned. 

Williams R M, Zwier J M and Verhoeven J W 1995 Photoinduced intramolecular electron transfer in a bridged Cgg (acceptor)-aniline (donor) system. Photophysical properties of the first active fullerene diad J. Am. Chem. See. 117 4093-9... 

Phenylhydrazine on exposure to light slowly darkens and eventually becomes deep red in colour salts of the base share this property but to a lesser degree, the sulphate and acetate (of the common salts) being most stable to light. Phenylhydrazine is largely used in organic chemistry to characterise aldehydes and ketones as their phenyl-hydrazones (pp. 342, 345), and carbohydrates as their osazones (pp. 136-140). It is readily reduced thus in the process of osazone formation some of the phenylhydrazine is reduced to aniline and ammonia. On the... 

The above simple experiments illustrate the more important properties of the anhydrides of aliphatic acids. For their characterisation, the reaction with aniline or p-toluidine is frequently employed. Alternatively, the anhydride may be hydrolysed with dilute alkali as detailed under Acid Chlorides, Section 111,88, and the resulting acid characterised as in Section 111,85. 

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

The observation of nitration nitrosation for mesitylene is important, for it shows that this reaction depends on the reactivity of the aromatic nucleus rather than on any special properties of phenols or anilines. 

The orbital and resonance models for bonding in arylamines are simply alternative ways of describing the same phenomenon Delocalization of the nitrogen lone pair decreases the electron density at nitrogen while increasing it m the rr system of the aro matic ring We ve already seen one chemical consequence of this m the high level of reactivity of aniline m electrophilic aromatic substitution reactions (Section 12 12) Other ways m which electron delocalization affects the properties of arylamines are described m later sections of this chapter... 

Oxidizing Properties. Nitric acid is a powerful oxidizing agent (electron acceptor) that reacts violentiy with many organic materials (eg, turpentine, charcoal, and charred sawdust) (19,20). The concentrated acid may react explosively with ethanol (qv). Such oxidizing properties have had military appHcation nitric acid is used with certain organics, eg, furfuryl alcohol and aniline, as rocket propellant (see Explosives AND PROPELLANTS). 

Other terms relating to physical properties include viscosity refractive index pour point, ie, the lowest temperature at which the oil flows flash point, ie, the temperature at which the oil ignites and aniline point, ie, the minimum temperature at which equal volumes of oil and aniline are completely miscible. These are determined under defined conditions estabHshed by ASTM. 

Other Reactants. Other reactants are used in smaller amounts to provide phenoHc resins that have specific properties, especially coatings appHcations. Aniline had been incorporated into both resoles and novolaks but this practice has been generally discontinued because of the toxicity of aromatic amines. Other materials include rosin (abietic acid), dicyclopentadiene, unsaturated oils such as tung oil and linseed oil, and polyvalent cations for cross-linking. 

The physical properties of aniline are given in Table 1 and vapor pressure data in Table 2. ... 

Aniline—formaldehyde resins were once quite important because of their excellent electrical properties, but their markets have been taken over by newer thermoplastic materials. Nevertheless, some aniline resins are stiU. used as modifiers for other resins. Acrylamide (qv) occupies a unique position in the amino resins field since it not only contains a formaldehyde reactive site, but also a polymerizable double bond. Thus it forms a bridge between the formaldehyde condensation polymers and the versatile vinyl polymers and copolymers. 

Vulcanization was first reported in 1839 with the discovery that heating natural mbber with sulfur and basic lead carbonate produced an improvement in physical properties (2). In 1906, aniline was the first organic compound found to have the abiUty to accelerate the reaction of sulfur with natural mbber (3). Various derivatives of aniline were soon developed which were less toxic and possessed increased acceleration activity. 

Hydrocarbon Solvents. Most hydrocarbon solvents are mixtures. Few commercial hydrocarbon solvents are single compounds. Toluene is an exception. Hydrocarbon solvents are usually purchased and suppHed on specification. The most important specification properties are distillation range, solvency as expressed by aniline cloud poiat and Kauri-Butanol (KB) value, specific gravity, and dash poiat. Composition requirements such as aromatic content and benzene concentration are also important ia many appHcations. 

Ethers, esters, amides and imidazolidines containing an epithio group are said to be effective in enhancing the antiwear and extreme pressure peiformance of lubricants. Other uses of thiiranes are as follows fuel gas odorant (2-methylthiirane), improvement of antistatic and wetting properties of fibers and films [poly(ethyleneglycol) ethers of 2-hydroxymethyl thiirane], inhibition of alkene metathesis (2-methylthiirane), stabilizers for poly(thiirane) (halogen adducts of thiiranes), enhancement of respiration of tobacco leaves (thiirane), tobacco additives to reduce nicotine and to reduce phenol levels in smoke [2-(methoxymethyl)thiirane], stabilizers for trichloroethylene and 1,1,1-trichloroethane (2-methylthiirane, 2-hydroxymethylthiirane) and stabilizers for organic compounds (0,0-dialkyldithiophosphate esters of 2-mercaptomethylthiirane). The product of the reaction of aniline with thiirane is reported to be useful in the flotation of zinc sulfide. 

Although occasionally in demand because of their good electrical insulation properties, aniline-formaldehyde resins are today only rarely encountered. They may be employed in two ways, either as an unfilled moulding material or in the manufacture of laminates. 

Aniline-formaldehyde resin has very poor flow properties and may be moulded only with difficulty, and mouldings are confined to simple shapes. The resin is essentially thermoplastic and does not cross-link with the evolution of volatiles during pressing. Long pressing times, about 90 minutes for a 5 in thick sheet, are required to achieve a suitable product. 

Some typical properties of aniline-formaldehyde mouldings are given in Table 24.2. 

St. Clair et. al. investigated a series of maleimide and nadimide terminated polyimides and developed LARC-13 [8,9]. Changing the terminal group from maleimide to nadimide, the value of the lap shear strength of a titanium lap shear joint increased from 7 to 19 MPa [9]. They also added an elastomeric component to the adhesive formulation. The introduction of 15 wt% of a rubbery component, ATBN (amine terminated butadiene nitrile polymer) and ADMS (aniline terminated polydimethyl siloxane) enhanced the adhesive properties as follows 19 MPa to 25 MPa (ATBN) titanium T-peel strength 0.2 kN/m to 1.4... 

Observable Characteristics - Physical State (as normally shipped) Liquid Color. Clear to light yellow turns yellow, brown or deep red on exposure to air and light Odor Aromatic, aniline-like. Physical and Chemical Properties - Physical State at 15 X and 1 atm. Liquid Molecular Weight 107.2 Boiling Point at 1 atm. 392, 200, 473 Freezing Point -11, -24, 249 Critical Temperature 790, 421, 694 Critical Pressure 544, 37.0, 3.75 Specific Gravity 0.998 at 20 °C (liquid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization 179.1, 99.5,4.16 Heat of Combustion -16,180, -8,990, -376 Heat cf Decomposition Not pertinent. 

The oxidizing properties of MnOy are utilized in the oxidation of aniline for the preparation of hydroquinone which is important as a photographic developer and also in the production of dyes and paints. 

Compare energies for meta and para-dinitrobenzenium ions (intermediates in nitration of nitrobenzene). Is the ordering the same as those observed for intermediates in toluene and aniline nitration Examine electrostatic potential maps. What does your result suggest about the electron donor/aceptor properties of the nitro substituent ... 

In 1887, Conrad and Limpach described the condensation of ethyl acetoacetate 5 with aniline 1 to provide enamine 6. Subsequent warming of the mixture provided quinoline 7. Limpach reported several years later that the yield of the cyclization step was improved when an inert solvent (e.g., mineral oil) was employed. While the cyclization step was normally quite facile at 240-280 °C, the physical properties and the methods described for the preparation of enamino-esters were inconsistent. 

The electronic properties of the aniline are important in the Doebner reaction. The reaction works best with electronic donating groups. Anilines substituted with a chlorine at the meta position consistently give low yields, but fluorine at the meta position seems... 

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