Drug Store Alcohol

[imp]

Why is isopropyl alcohol so widely sold and used rather than propyl alcohol? It would seem to me that the isomeric form would be more difficult to make, and therefore more costly.

 

Or, is the common drug store stuff actually a mixture of the two? Of course, the ingredients listing would not reveal that. imp

[John Cuthber]

IPA is easier, and therefore cheaper, to make than n propanol.

[DrDNA]

From Wikipedia:

"Isopropyl alcohol is produced by combining water and propylene.[1] There are two processes for achieving this: indirect hydration (sulfuric acid process) and direct hydration. The former process, which can use low quality propylene, predominates in the USA while the latter process, which requires high-purity propylene, is more commonly used in Europe. These processes give predominantely isopropyl alcohol rather than propan-1-ol because the addition of water (or sulfuric acid) to propylene follows Markovnikov's rule."

[MagicJigPipe]

Doesn't it have something to do with the OH being more likely to react with the most subsituted C? Hence, the C with 3 bonds to other carbons. The other 2 carbons have only 2 and 1 bonds with other carbons.

[John Cuthber]

OK, draw me a diagram and show me the "C with 3 bonds to other carbons".

[MagicJigPipe]

Propylene (Propene)

 

H H H

| | |

C=C-C-H

| |

H H

 

The number 2 carbon. =C- <---- 4 bonds. 3 to other carbons. 1 Hydrogen.

 

BTW, that sounded like you were being condescending. If so, don't. If not, I apologize for thinking so.

[Darkblade48]

Just to let you know (I'm not sure if it's the formatting of the forums), but the hydrogens that you've drawn for propene are incorrect.

 

And, yes, as mentioned, isopropyl alcohol is the main product due to Markovnikov's rule...

[Mr Skeptic]

Propylene (Propene)

H H H
| | |
C=C-C-H
|   |
H   H    

The number 2 carbon. =C- <---- 4 bonds. 3 to other carbons. 1 Hydrogen.

 

BTW, that sounded like you were being condescending. If so, don't. If not, I apologize for thinking so.

 

just use [ code ] [ /code ] tags, which will preserve the spaces and make all characters the same size.

[MagicJigPipe]

Ok, thank you. And yes, I originally had the structure right, it seems as if it condensed the spaces between the hydrogens.

[John Cuthber]

OK, but OH doesn't add to propene; it adds to the propyl cation which doesn't have any double bonds. The proton adds to the alkene to give this isopropyl cation (which is the more stable of the 2 possible cations).

And that's why I was being condescending.

[YT2095]

And that's why I was being condescending.

 

well DON`T!

we`re civilised Chemists here, there is No need for any Gruntish attitude, we may discuss things as Civilised people!

 

after all Chemistry is the Father of All Science

we still need to set an Example!