117 



ORGANIC RADICALS. 



ORGANOMETALLIC BODIES. 



118 



relations. Further, just as we bare uniatomic, biatomic, and teratomic 

 metals (tliat is, metals capable of combining with one, two, or three 

 equivalents of other elements), so we have organic radicals which com- 

 port themselves in exactly the same manner in their modes of combi- 

 nation. Thus ethyl (C,H S ) is a uniatomic, ethylene (C 4 H,") a biatomic, 

 and the radical of glycerin (C,H 5 '") a teratomic radical. When a radical 

 has such a polyatomic character, its degree is represented by dashes 

 placed after the formula, as in the cases just mentioned. 



There are several families of homologous organic radicals, and they 

 are usually distinguished by certain general formula. One of the most 

 important of these families has the general formula CnHn + i, in which 

 n represents an even number, such as 2, 4, 6, &c. The following are a 

 few of the chief radicals belonging to this family : 



Methyl 



C,II, or 



Butyl 

 Amyl 



C.H, or 

 C 9 H, or ^ 

 C^U,, or '[ 



A second family hag the general formula CnHn 7 . None of its 

 members are yet known in a separate state, but analogy admits of no 

 doubt as to their existence in certain well-known organic compounds. 

 The following are some of the most important members of this 

 family : 



rb*7l ..... C 1S H S or C| J 



Tolurayl ..... C, .H, or ' *^' J 

 Cnmenyl ..... C^H,, or 

 Cymcnyl ..... C, H 1S or 



A third family has the general formula CnHn i. It has hitherto 

 been very little explored, and the only member known with certainty 



*">> J 



Allj-1 



c.n. or 



All the families above described contain only uniatomic radicals, but 

 by the abstraction of one equivalent of hydrogen they all yield cor- 

 responding butomic radicals. Thug : 



C,H 5 - 



C t H t " 



Ethyl. r.thylcne. 



The following are the chief biatomic radicals of the form CnHn : 



Methyleno C,H," 



Ethylene C H V,' 



Propylme ....... CjH 4 



Botylene C,H," ( 



Amylene C 10 II, " 



With the exception of methylcnc, all these biatomic radicals can be 

 readily obtained in a separate state. 



A family of teratomic radicals of the form CnHn i appears also to 

 exist, although up to the present time only one member is known, and 

 that only in combination. Glycerin contains this radical, which is 

 termed 



Glyceryl C.H,'" 



All the radicals hitherto considered are positive or baxyl'> radicals, 

 but by the exchange of two equivalents of hydrogen for two of oxygen 

 they are all transformed into negative or thlvroiu radicals ; thus, the 

 positive radical ethyl, minus two atoms of hydrogen, plus two of oxygen, 

 passes into the negative radical othyl or acetyl : 



C,H, + O, - H, = C.H.O, 



Ethyl. 



Othyl. 



Hitherto uniatomic negative radicals alone have been clearly estab- 

 lished, but there can be no doubt that biatomic and teratomic positive 

 radicals, by a similar substitution of oxygen for hydrogen, pass into 

 corresponding negative radicals of the same polyatomic character. 



The following are some of the most important uniatomic negative 

 radicals: 



1. Of the form CnUn- iO.,. Derivatives from CnHn -f I. 



Othyl or tyl . 

 Propionyl . 



CH.O, Of gJ J 



. C.ll.O, or $^| } 



2. Of the form CnHn o 2 . 

 BenzByl . . 



Toluyl . 

 Cumyl 



Derivatives from CnHn 7. 



. C II O or C I* H S* 1 

 11 '* C 14 H 5 2 J 



. . C 1(> H,0 2 or c^Hio,} 



3. Of the form CnHn 3 2 . Derivatives from CnHn i. 

 Acryl . . . . . C 6 H 3 O 2 or p 6 -rr 3 o 2 | 



In addition to the bodies above described, another class, termed 

 double radicals, are known to chemists. These are formed by the 

 union of any two single positive radicals, or of a positive with a negative 

 radical. No double negative radical has yet been obtained. The fol- 

 lowing instances will suffice to indicate the composition of the double 

 radicals : 



Ethyl-amyl 



H 5 ) 

 H ii J 



Acetone or methyl-othyl 



C 4 H, 

 C,. .. 

 C 4 H 3 2 1 

 CM, i 



The double radicals containing both a positive and a negative con- 

 stituent are better known under the name of ketones. [KETONES.] 



It has been stated above that of the single radicals, those belonging 

 to the positive division only have been isolated, and of these the 

 members of the family CnHn ? are entirely unknown in a separate 

 state. The two methods admitting of general application for the 

 isolation of the positive radicals, are the following : 



1. The action of zinc, potassium, or sodium, upon the iodides of the 

 radicals. Thus, for the isolation of ethyl : 



I 



c.n. 



-f Zn, = 2ZnI + 



Iodide of Ethyl. 



Ethyl. 



2. By the action of nascent oxygen, evolved from the positive polo 

 of a voltaic battery, upon the fatty acids. Thus, for tho isolation of 

 methyl : 



Carbonic acid. 



CM,J 

 Mcthvl. 



ORGANOMETALLIC BODIES. A numerous family of chemical 

 compounds in which compound organic radicals, such as methyl, ethyl, 

 &c., are united with metals, in a manner analogous to that in which 

 the elementary radical chlorine is combined with sodium and zinc, in 

 sea-salt and chloride of zinc. If, for instance, in chloride of zinc wo 

 replace the chlorine by ethyl, we produce one of the bodies belonging 

 to this family, namely, zincethyl : 



ZnCl Zn(C 4 H 5 ) 



Chloride of zinc. 



Zincethyl. 



Although organometallic bodies as a distinct class of organic com- 

 pounds are, with one exception, the creation of the last ten years, yet 

 the derivatives of these bodies have been known for a much longer 

 period. From the time that an organic acid was first united with a 

 metallic base these organic compounds containing metals date their 

 existence. It is true that such compounds containing a metallic con- 

 stituent have not been regarded from this point of view, but a little 

 consideration will serve to show that they stand in the same relation 

 to organometallic bodies, in the strict sense of the term, as the alcohol 

 radicals occupy with regard to the ethers, alcohols, acids, and numerous 

 other families derived from these radicals. 



Thus, zincethyl yields by oxidation ethylate of zinc 

 ZnC.II, + O, = ZnO, C.H b O 



Zincethyl. Ethylate of zinc, 



a body which, although unknown until formed by this re-action, has 

 undoubted and well-known analogies in the ethylates of potash and 

 soda. 



By suitable processes of oxidation, ethylate of zinc may be converted 

 into acetate of zinc : 



zno,c,n s o 



40 



g}o. 



Again, potassium-methyl and sodium-methyl under the influence of 

 carbonic acid yield the acetates of potash and soda : 



Sodium methyl. Carbonic ncid. 



Acctatcofsoda. 



Such being the relations between organometallic bodies in the usual 

 acceptation of the term, and that far more numerous clasw of derivatives 

 to which the same name might without impropriety be applied, it is 



