Oxygen by Sulphur on Boiling-points of Compounds. 459 



He does not, however, mention the way in which this effect 

 is reversed in the cases in which the oxygen of the hydroxyl 

 group is replaced by sulphur, and I therefore conclude that 

 it escaped his notice. By examining the large number of 

 boiling-point data given by him in his tables I have found 

 the following rule to be perfectly general : — 



The replacement of oxygen by sulphur in a compound always 

 raises the boiling-point except in those cases in which the oxygen 

 of the hydroxyl group is replaced by sulphur , and. then the re- 

 verse effect is very marked. 



In obtaining data in proof of this I have been confined 

 of course mainly to organic compounds, and of these I have 

 only given the simpler instances, and such of the more com- 

 plicated compounds as have a known structural formula. 

 The reason for this is obvious, since Kopp has shown that the 

 boiling-point of isomeric hydrocarbons is not the same, show- 

 ing that a mere rearrangement of the atoms in a molecule is 

 sufficient to affect the boiling-point without any change in 

 number or kind. The fact is further exemplified in the series 

 of ethyl-carbonates given above. 



In the following list of compounds containing hydroxyl 

 and their sulphur analogues, it will be seen that the replace- 

 ment of the OH by the SH group always lowers the boiling- 

 point, and that in the case of bodies of low molecular weight 

 the difference is considerable, but decreases as we ascend a 

 homologous series*. 



H 2 S 



CH 3 SH 



C 2 H 5 SH 



(OH 2 SH) 2 



CH 2 CHCH SH . 

 CH 3 CH 2 CH 2 SH . 

 (OH 3 ) 2 CHSH .... 

 (OH 3 )oCHCH 2 SH. 



0H(CH 3 ) 2 CH o CH 2 SH 

 CCl 3 CHOHSH 



O t5 H 4 (SH) 2 



OH 3 (CH 2 ) 4 CH 2 SH 



6 H 5 OH 2 SH 



6 H,CH 3 SH(a) .. 

 » (0) - 



(r) •• 

 CH3COSH 



C 6 H,OHSH(a) 



-61-8 



21 



36-2 

 146 



90 



67 



57 



88 



84 

 120 

 123 

 172 

 243 

 145 

 194 

 188 

 188 

 188 



93 

 216 



H,0 100 



CH3OH 67 



2 H 3 OH 78-4 



(CH o 0H) o 197 



CH 2 OHCII 2 OH 96 



0H 3 0H o CH o 0H 97 



(OH 3 ) 2 CHOH 83 



(CH^CHCH.OH 108 



CH 3 CH o CH0HCH 3 99 



0H(0H 3 ") o CH. ) 0H 2 0H ... 131-5 



CCl 3 CHOHOH 149 



G H 5 OH 180 



6 H,(OH), 270 



CH^CH.OlCHoOH 157 



C g H 6 CH;OH..: 205 



C G H i OH;OH(a) 188 



08) 201 



(r) 198 



OH3OOOH 117 



CeH.OHOH^) 245 



Diff. 



16?-8 

 46 

 42 

 51 

 6 

 30 

 26 

 20 

 i:> 

 11-5 

 26 



12 



U 

 

 13 

 10 

 24 

 29 



285 C 10 H 7 (OH)(a) 278-80 



* The only exception to the rule is that marked t, and is in the case of 

 a body of high molecular weight and complicated constitution. 



