C6H5

This article appears in Volume V25, Page 895 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: BUN-CAL

C6H5 .CH7 H.
These facts may be explained in the same way as with carbon, by admitting tetrahedral grouping. A

special

SPECIAL

feature, however, wanting with carbon, is that compounds with one atom only of the

element

ELEMENT (Lat. elementum)

in question have been obtained as antipodes. A second observation of some

interest

INTEREST

is that the compounds in question are electrolytes and that, as in solutions, where they are split up into ions, activity must be due to the last, the ionic complex, for in-stance, R1R2R3S, must cause optical rotation.
Optical antipodes have also been obtained with quinquevalent nitrogen in compounds of the type: RiRIR3RaNR6. Le Bel observed these in methylethylpropyl-isobutylammonium chloride; since then Pope and Peachey and Wedekind studied the same question more thoroughly, and as a general result it is now stated that ammonium compounds with four different radicals behave as asymmetric carbon compounds. The explanation may be that the four radicals arrange themselves in the two possible tetrahedral configurations, and that the fifth

element

ELEMENT (Lat. elementum)

or group, e.g. chlorine or hydroxyl, more loosely linked, finds its fittest place, as shown in figs. 7 and 8.
2. Stereo-isomers Without Optical Activity.The

chief

CHIEF (from Fr. chef, head, Lat. caput)

cases here
belong to the derivatives of nitrogen with

double

linking and the metallic compounds which have been chiefly studied by Werner.
The nitrogen compounds showing stereo-

isomerism

ISOMERISM

belong to two classes, according to the structural formulae, containing C:N or N :N ; in their general behaviour they seem related to the ethylene derivatives.
The first group was detected by

Victor

Meyer and Goldschmidt in C6H6C :NOH
benzildioxime:
CsHs :NOH.
Later investigations, especially by Hantzsch, showed that a grouping
R1C R2 R1CR2
XN N X
gives rise to stereo-

isomerism

ISOMERISM

, the supposed difference being that X is either more close to R, or to R2. This peculiarity is observed in the aldoximes and ketoximes, derived from aldehydes and ketones on treatment with

hydroxylamine

HYDROXYLAMINE, NH2OH

, and the two simplest examples are ethyl-aldoxime H3CCH:NOH, and phenyl-benzyl-ketoxime, (C6H5) (C6H4CH2) C : NOH. As the behaviour of these stereo-isomers much resembles that of ethylene-compounds, they are often indicated as cis- and trans-forms.
The second stereo-isomerism in nitrogen-compounds was detected by Schraube in potassium benzenediazotate, and may perhaps be reproduced by the following symbols:
C6HsN and C6H6N
KON NOK.
The last group of stereo-isomers, in which insight is most difficult yet, is that of Werner's complex metallic compounds, observed with

cobalt

COBALT (symbol Co, atomic weight 59)

, platinum and chromium. No enantiomorphous character throws light here, and there is no relation to ethylene derivatives.
With

cobalt

COBALT (symbol Co, atomic weight 59)

the fact is that in the hexammonic cobalt salts, e.g. Co(NH3)sC13, when NH3C1 is substituted by NO2 isomerism appears as soon as the number of substituents is two ; Jorgensen's flavo-salts Co(NHa)a(NO2)2C1, and Gibbs's isomeric croceo-salts offer examples. Werner puts forward that a grouping of (NH3)6 at the summits of a regular

octahedron

OCTAHEDRON (Gr. 6K-rw, eight, Mpa, base)

around Co may explain this.
I00
48 14
o8
42,
Platinum compounds such as (H3N)i PtCl2 have been obtained in fig. 2) this point is seen simply, together with a number of other points which together form the so-called " horopter." According to Joh. Muller, Helmholtz, Hering, Volkmann and others, these are those points of the object-space (e.g. Q and R in fig. 2), whose images fall on identical or corresponding spots on the retina, by which are meant those points on the retina whose nerve filaments are united and which are equidistant in the same direction from the centre of the yellow spot (see EYE; VISION). The horopter varies according to the position of the fixed spot in the object-space; for example, it is the ground
two forms, Werner admitting here the following plane configurations
ClPtz Cl Cl NH3
> and )Pt(
HEN/ \NH3 H3N/ Cl
shows a behaviour analogous to that of cobalt, and analogous space-formulae may be used here. But, in a general way, at present it is extremely difficult to decide upon their value.
(annual since 1904). (J. H. vAN'T H.)

End of Article: C6H5

If you wish, you can link directly to this article.

<a href="http://jcsm.org/StudyCenter/Encyclopedia/BUN_CAL/C6H5.html">
C6H5
</a>

(Previous)
C6H4C CH NH

(Next)
C6H5CHO

JCSM was founded in 1997 and exists to help the community and bring people into a life-changing and productive relationship with Jesus Christ. JCSM offers over 200,000 free web pages, including its weekly inspirational emails that were sent continuously for over a decade.

Jesus Christ Saves Ministries
P.O. Box 9297
San Diego, CA 92169
1-888-887-0417 or Email