ores ON ‘SCIENTIFIC us eA i, td See 119 
- | 
OS het ons cals 4: 2Naniig It is to be expected that in this reaction 
a ie chlorides give a better yield than bromides or iodides. 
The higher alkylhalides have also the property —not yet more closely examined — 
~ of yielding saturated hydrocarbons (sometimes accompanied by ring-formation) when 
‘treated with alkali cyanides, alkali, aniline, 8c., analogous to the formation of the 
cyclopropane ring by elimination of HBr from bromodimethylglutaric acid ester according 
BS to Perkin and Thorpe?): — 
CH2- CHa: CHH—R- CH CH OHESR: 
i Pest | + HBr 
CH, - CH: CH,Br sl . CH SCH CH 2 
The properties of the ‘ethylene linkages still hide a lot of unsolved problems. The 
‘ addition of halogens, especially bromine, to thé olefines, is a universal, characteristic 
reaction; and yet there exists a great difference in respect to the rapidity, and power 
of reaction between the substituted ethylenes. Whilst ethylene and propylene even at 
— 80° add bromine with a speed not to be measured, there are ethylene derivatives 
with strong electronegative groups (COOH, COOR, Cols) which scarcely react with 
bromine, or not at all’). 
Up to now it was assumed that the addition of water to Bibtnes in dilute sulphuric 
acid, ‘resulted exclusively ane the hydrolysis of the awe ite acid ester in the 
following sense: — 
Be "eG 5 Weekes PReCHae ce yee OH. OH 
Be 2 -CH-OSG,H ~ R,-CH-OH OH ISOH 
(I) Orthosulphuric acid. 
According to another, more modern view the hydration is explained by the temporary 
formation of the orthosulphuric acid ester (I). Also water alone reacts, in a very few. 
_ Cases, with compounds having doubled linkages, as with the ketenes (Rx)C=CO. Bodies 
containing the group —CH= Cie C—O, as mesityl oxide, citral, pulegone, are 
_ often hydrolysed by diluted acids with the rupture of the chain. Further, compounds 
containing this group — as citral, citronellal—add on sodium bisulphite; the additive 
‘power for, malonic acid ester, acetoacetic ester, hydrocyanic acid and unsaturated 
compounds of this kind is less well studied. It may be-mentioned here, that the 
- group —CH=CH-CO— determines the characteristic odour of many substances, such 
as that of violets, 
A very general and yet little Sapieiakd siacerty of the olefines is their tendency 
to polymerise. When the -process takes place in the presence of concentrated sulphuric 
acid, it can be explained by. the formation of an alkylsulphuric acid ester: —on the 
other hand, the process of polymerisation under the influence of metallic sodium, heat 
and air is not explained. Here, without doubt, the fundamental properties of the mole- . 
cule, and the theory of valency must be brought into consideration. Also the influence 
of heat and light on the vibrations of the electrons would have to be taken into 
account, and perhaps in connection therewith, the ‘frequent changes of position of 
the double bonds.’ 
Instability of structure is a Striking characteristic of higher aliphatic compounds. 
Tsobuty! alcohol and the primary isobutylhalides (CH;)sCH-CH2X yield a mixture of 
y _ isobutylene (CH;),C=CH, and of @- and anormal butylene CH;CH=CH:CHs and 
2) Journ. Chem. Soc. 75 (1899), 48. — *) Berl. Berichte 37 (1904), 3317. 
