Radicles, organic

The polarimeter is an instrument with which the essential oil chemist cannot possibly dispense. The hypothesis, first seriously enunciated by Le Bel and van t Hoff, that substances which contained an asymmetric carbon atom i.e. a carbon atom directly united to four different atoms or radicles) were capable of rotating the plane of polarisation of a beam of polarised light, has now become a fundamental theory of organic chemistry-. The majority of essential oils contain one or more components containing such a carbon atom, and so possess the power of effecting this rotation. In general, the extent to which a given oil can produce this effect is fairly constant, so that it can be used, within limits, as a criterion of the purity or otherwise of the oil. 

The anhydrides of the organic acids can also be regarded as di-acyhxides (acyl = acid radicle, e.g. CH3.CO = acetyl) and can be thus assimilated to the ethers, or dialkyl oxides. The ethers are amongst the most indifferent of all the conpounds of organic chemistry. Whence, then, comes the great reactivity of the similarly constituted anhydrides The weak point in the anhydride molecule is to be found, not at the... 

THE GRIGNARD AND FRIEDEL-CRAFTS SYNTHESES. ORGANIC RADICLES... 

We might expect that the reaction would lead to the formation of tetraphenylmethane from benzene and carbon tetrachloride in the presence of aluminium chloride, but this is not so. In this case the fourth Cl-atom remains in the reaction product. Triphenylchloromethane (C6H5)3CC1 has acquired extraordinary importance because, when applied in the Wurtz reaction, it made possible the discovery of the first free organic radicle (Gomberg, 1900). Compare p. 352. 

Hydrogen chloride reacts in light to form triphenylmethane and triphenylcMoromethane. The reaction is reversible (Schlenk). NO, N02, and many organic radicles add themselves to triphenylmethyl. The combination with quinone is analogous (Schmidlin). 

This compound is surprisingly similar to N02, not only in colour, but also in many reactions. It, however, lacks all tendency to lose the radicle state and to dimerise like nitrogen peroxide. In this respect it resembles nitric oxide, whereas the organic relatives of nitric oxide are more like nitrogen peroxide. 

Metallic Radicles.—The organic matter in the compound is destroyed either (a) by heating to redness for some time in contact with air in a quartz or porcelain crucible, or (b by oxidising with a mixture of cone, nitric and sulphuric acids. After decomposition is complete, the residue is examined by the usual tests for inorganic radicles. In (a) volatile radicles such as mercury, arsenic and ammonium will be lost. 

Aqueous solutions of calcium chloride, ferric chloride or silver nitrate give precipitates or colorations with certain organic acids which are valuable for the detection of these acids. It is important to use neutral solutions of the acids which at the same time do not contain metallic radicles likely to react with the reagents added. Thus the addition of calcium chloride to a solution of lead acetate may produce a precipitate of lead chloride. A neutral solution, which should be of about 10% concentration, prepared as follows, usually avoids such complications —... 

The basic properties of the aromatic amines decrease with the number of radicles introduced the primary aromatic amines are stable the secondary aromatic amines are decomposed by water and the tertiary aromatic amines are unstable. In organic chemistry, compounds containing the monadic group NH2 are called amines or amides and compounds with the dyadic group NH are called imides. The existence of compounds like... 

About the same time Frankland and Duppa, using the same reaction, discovered that the hydrogen atoms of the methylene group are replaceable by sodium and various organic radicles. 

This substance is strongly acid, forming salts and esters, in which the hydroxyl hydrogen is replaced by metals and by organic radicles respectively. The reaction led to the discovery of many other hydroxy-metliylene bodies possessing similar properties. 

Both metals form compounds with organic radicles, in which the metals themselves are tetravalent. 

It is interesting to note that ferric salts of organic acids such as citric, tartaric, etc., are not as a rule ferric salts in the ordinary acceptation of the term. The iron has entered into the electro-negative radicle in an analogous manner to copper in the organic copper derivatives.4 In ferric oxalate and in the ferricyanides, which latter do not contain hydroxylic or carboxylic groups, the iron is similarly in the negative radicle. 

The organic compounds having aggressive action usually contain atoms of halogen, sulphur or arsenic or radicles such as —NOg, —CN, etc., in their molecules. It is to these atoms or radicles as well as to the molecular structure that the physio-pathological action is nowadays attributed. 

The arsenical war gases contain halogen atoms or organic radicles such as —CN, —SCN, etc., besides the arsenic atom. The nature of the aggressive action depends on the number and the nature of the organic radicles with which the arsenic atom is linked. 

An increase in toxic power is also found in organic compounds whose molecules contain a cyanide radicle thus diphenyl cyanoarsine is more irritant than diphenyl chloroarsine ... 

Toxophor-Auxotox Theory. The theory of toxophors and auxotoxes, first elaborated by Ehrlich for toxic substances and later applied by Nekrassov to the war gases, attributes the physiopathological properties of these substances to special atoms or radicles in a similar manner to Witt s theory regarding the colour of organic substances. 

The Embryo, consisting of a single shield-shaped cotyledon adjoining the endosperm, the plumule or rudimentary bud at the end of the caulicle or rudimentary stem and the radicle 6r rudimentary root, with its tip covered by a root cap. Continuous with the root cap is a root sheath or coleorhiza. The cotyledon or seed leaf consists of two parts the scutellum which lies next to the endosperm, and is an organ of absorption and the sheating portion which surrounds and protects the rest of the embryo. 

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