THE ALUMNI JOURNAL. 



The corresponding iodine comp. is iodo- 

 form. Tetrachlor-methane or carbon 

 tetra chloride CCl^ a liquid, employed as 

 a solvent. 



Of the next higher homologue ethane, 

 we have the following halogen products : 



Mono-chIor-etha7ie or ethyl chloride Co 

 H5CI, an ethereal liquid, owing to its 

 great volatility it is employed as a local 

 anaesthetic, benumbing the sense of feel- 

 ing. 



Mono-brom-ethane or ethyl bromide C2 

 HsBr. an anaesthetic like ether. 



On treating the above halogen alkyls 

 with caustic alkali the halogen is re- 

 moved with its nearest hydrogen atom, 

 yielding the unsaturated hydro-carbons 



CH, 



as ethylene || The bromine compound 



CH, 

 CH^Br. 



I Ethylene bromid is employed in 



CH.Br. 



epilepsy. Tetraiod ethylene Co I, called 

 diodoform offered as substitute for iodo- 

 form. To this class the anaesthetic /^w/a/ 



tri-methyl-ethvlene || ^f;- 



belongs. 



The next homologue of this .series is 

 propane, having two different kinds of H 

 atoms ; derivatives arise from the substi- 

 tution of the H in either of the end 

 carbon atoms, known as "normal," 

 while those arising from the substitution 

 of H in the middle one, are known as 

 "iso." Among the higher homologues 

 with greater number of carbon atoms, 

 the number of isomers increase accord- 

 ingly. 



If we replace H atoms in the paraffin 

 hydrocarbons by hydroxyl groups (OH) 

 we form corresponding alcohols. Among 

 those containing one hydroxyl are 

 methyl alcohol (CH3-OH), ethyl alcohol 

 C2H5OH). Tertiary-amyl-alcohol or amy- 



lene-hydrate 



CH, 



CH3 — C — OH is an oily- 

 xCoHg-'^ / 



like liquid, employed as a hypnotic. 



We have alcohols which contain more 

 than one hydroxyl group, each hydroxyl 

 being of course attached to a different 

 carbon atom. These are called diatomic 

 alcohols or glycols, the simplest being 



/ CHoOH 



Glycerin is a 



ethylene glycol. \ 



icH.30H/ 



propenyl alcohol, (triatomic CsH.XOH),). 

 The tetra, penta, and hexatomic alcohols 

 form solid crystalline compounds of sweet 

 taste ; for ex. mannite CoH,(OH% and 

 dulcite. 



If we substitute an SH group for a 

 hydrogen in methane, or sulphur for an 

 oxygen, in an alcohol, we obtain the 

 mercaptans, these are liquids of very 

 unpleasant, penetrating odor, ethyl mer- 

 captan being CoH, SH. 



By partial oxydation of the primary 

 alcohols we obtain the aldehydes ; 



CH3 CH3 



I +0= I +H,0 



CH.OH CHO 



Ethyl Alcohol. Ethyl or Acetic Aldehyde. 



these are distinguished from the alcohols, 

 in that they contain two atoms less of 

 hydrogen, and are characterized by the 

 group— CHO. A 40% solution of formal- 

 dehyde in HoO is Schering's Formalin a 

 powerful germicide. On adding a little 

 sulphuric or hydrochloric acid to ethyl 

 (acetic) aldehyde CH3 CHO it undergoes 

 polymerization, with formation o'i paralde- 

 hyde (CH3-CHO)3 a liquid hypnotic. 



If we replace three hydrogens of the 

 alkyl, in acet-aldehyde by three atoms of 

 the halogens CI or Br., we obtain chloral 

 C Cla-CHO or bromal C Brj-CHO. Three 

 atoms of chlorine thus introduced into 

 butyl-aldehyde yields croton chloral or 

 tri-chlor-butyl'-aldehyde (C ClaCHo.-CTH, 

 CHO). These aldehydes- unite witli'i 



