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DIPHENYL (phenyl benzene), C6H5

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Originally appearing in Volume V08, Page 290 of the 1911 Encyclopedia Britannica.
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DIPHENYL (phenyl See also:benzene), See also:C6H5 .CsH5, a See also:hydrocarbon found in that fraction of the See also:coal-See also:tar distillate boiling between 240-300° C., from which it may be obtained by warming with sulphuric See also:acid, separating the acid layer and strongly cooling the undissolved oil. It may be artificially prepared by passing benzene vapour through a red-hot See also:tube; by the See also:action of See also:sodium on brombenzene dissolved in See also:ether; by the action of stannous chloride on phenyldiazonium chloride; or by the addition of solid p henyldiazonium sulphate to warm benzene (R. MOhlau, Berichte, 1893, 26, r997) CSH5N2•HSO4+CSH6=H2SO4+N2+CSH5•C6H5. L. Gattermann (Berichte, 189o, 23, 1226) has also prepared it by the decomposition of a See also:solution of phenyldiazonium sulphate with See also:alcohol and See also:copper See also:powder. It crystallizes in plates (from alcohol) melting at 7o-71° C. and boiling at 2540C. It is oxidized by chromic acid in glacial acetic acid solution to benzoic acid, dilute nitric acid and chromic acid mixture being without effect. It is not reduced by hydriodic acid and See also:phosphorus, but sodium in the presence of amyl alcohol reduces it to tetrahydrodiphenyl C12H14. See also:DIPHTHERIA a membranous exudation on a mucous See also:surface, generally on the tonsils and back of the See also:throat or pharynx. In See also:general the symptoms at the commencement of an attack of diphtheria are comparatively slight, being those commonly accompanying a See also:cold, viz. chilliness and depression. Sometimes more severe phenomena See also:usher in the attack, such as vomiting and See also:diarrhoea. A slight feeling of uneasiness in the throat is experienced along with some stiffness of the back of the See also:neck.

When looked at the throat appears reddened and somewhat swollen, particularly in the neighbourhood of the tonsils, the soft See also:

palate and upper See also:part of pharynx, while along with this there is tenderness and swelling of the glands at 'the angles of the jaws. The See also:affection of the throat spreads rapidly, and soon the characteristic exudation appears on the inflamed surface in the See also:form of greyish-See also:white specks or patches, increasing in extent and thickness until a yellowish-looking false membrane is formed. This See also:deposit is firmly adherent to the mucous membrane beneath or incorporated with it, and if removed leaves a raw, bleeding, ulcerated surface, upon which it is reproduced in a See also:short See also:period. The See also:appearance of the exudation has been compared to wet See also:parchment or washed See also:leather, and it is more or less dense in texture. It may See also:cover the whole of the back of the throat, the cavity of the mouth, and the posterior pares, and spread down-wards into the See also:air-passages on the one See also:hand and into the alimentary See also:canal on the other, while any See also:wound on the surface of the See also:body is liable to become covered with it. This membrane is See also:apt to be detached spontaneously, and as it loosens it becomes decomposed, giving a most offensive and characteristic odour to the breath. There is See also:pain and difficulty in swallowing, but unless the disease has affected the larynx no affection of the breathing. The See also:voice acquires a snuffling See also:character. When the disease invades the posterior pares an acrid, fetid See also:discharge, and some-times also copious bleeding, takes See also:place from the nostrils. Along with these See also:local phenomena there is See also:evidence of constitutional disturbance of the most severe character. There may be no' See also:great amount of See also:fever, but there is marked depression and loss of strength. The See also:pulse becomes small and frequent, the countenance See also:pale, the swelling of the glands of the neck increases, which, along with the presence of albumen in the urine, testifies to a See also:condition of See also:blood poisoning.

Unless favourable symptoms emerge See also:

death takes place within three or four days or sooner, either from the' rapid See also:extension of the false membrane into the air-passage, giving rise to See also:asphyxia, or from a condition of general collapse, which is sometimes remarkably sudden. In cases of recovery the See also:change for the better is marked by an See also:arrest in the extension of the false membrane, the detachment and expectoration of that already formed, and the healing of the ulcerated mucous membrane beneath. Along with this there is a general improvement in the symptoms, the See also:power of swallowing returns, and the strength gradually increases, while the glandular enlargement of the neck diminishes, and the albumen disappears from the urine. Recovery, however, is generally slow, and it is many See also:weeks before full convalescence is established. Even, however, where diphtheria ends thus favourably, the See also:peculiar sequelae already mentioned are apt to follow, generally within a period of two or three weeks after all the local evidence of the disease has disappeared. These secondary affections may occur after mild as well as after severe attacks, and they are principally in the form of See also:paralysis affecting the soft palate and pharynx, causing difficulty in swallowing with regurgitation of See also:food through the See also:nose, and. giving a peculiar nasal character to the voice. There are, how-ever, other forms of paralysis occurring after diphtheria,espccially that affecting the muscles of the See also:eye, which produces a loss of the power of See also:accommodation and consequent impairment of See also:vision. There may be, besides, paralysis of both legs, and occasionally also of one See also:side of the body (hemiplegia). These symptoms, however, after continuing for a variable length of See also:time, almost always ultimately disappear. Under the name of the Mal um Egyptiacum, Aretaeus in the 2nd See also:century gives a See also:minute description of a disease which in all its essential characteristics corresponds to diphtheria. In the 16th, Many substitution derivatives are known: the monosubstitntion derivatives being capable of existing in three isomeric forms. Of the disubstitution derivatives the most important are those derived from diparadiaminodiphenyl or See also:benzidine (q.v.).

See also:

NH2 Orthoaminodiphenyl, <—>—<_ >, is prepared by the action of See also:bromine and See also:caustic soda on orthophenylbenzamide (R. See also:Hirsch, Berichte, 1892, 25, 1974) ; when its vapour is passed over heated See also:lime, See also:carbazol (q.v.) is formed.

End of Article: DIPHENYL (phenyl benzene), C6H5

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