naptha, (Caution: Chemistry)

[Tim Keenan & Rebecca Counts]

Howard S. Rosen wrote:
> 
> Hi Jim,
> 
> First I want to be sure of my own terminology. I am not sure about naptha
> and mineral spirits being the same. I *think* they are different and I am
> hoping that you will clear this point up for me.
> 

Dear List

Herewith more than you probably wanted to know about alkanes and 
silicones:

Mineral Oil, Mineral Spirits, Naphtha:

None of the names of these compounds is restrictive, and they may mean 
somewhat different things in different countries.

Naphtha (thus spelled) generally refers to highly refined hydrocarbons of 
the alkane type--usually mostly pentanes and hexanes, (the lightest and 
most volatile fraction of what we normally call gasoline).  They are 
linear molecules of the general formula Cn-H(2n+2), where methane is 
C-H4, ethane is C2-H6 etc.

If the formatting will hang together thru cyberspace, pentane looks like 
this:
  H H H H H
  | | | | |
H-C-C-C-C-C-H
  | | | | |  
  H H H H H

The other alkanes (sometimes known as paraffins) are simply shorter or 
longer chains of the same general formula. The chains of the longer ones 
may be branched, with side chains of identical basic formula.

Naphtha has a flash point of below -40 C, which just happens to be the 
same as -40 F.

Mineral Spirits generally refers to a heavier fraction of the alkane 
spectrum, more in the range of what we know as diesel fuel or kerosene, 
but much more refined, and hence a less objectionable smell. It generally 
has a flash point around 0 C or 32 F, and a boiling point of 80 to 130 C. 
Mineral spirits are sometimes known as varnish-makers' and painters' 
Naphtha.  In Britain, Kerosene is known as paraffin.  The wax we in North 
America know as paraffin is mostly very long-chain alkanes.

Mineral Oil is also known as liquid petrolatum.  It is, again, just a 
heavier fraction of the same series, mostly of straight-chain alkanes.  
If it has a lot of branched-chain alkanes, what you have is commercially 
known as Vaseline.

As an interesting aside, the family of compounds known as silicones have 
a similar architecture.  The Element Silicon (Si) is commonly confused 
with the family of silicones, but it is just part of the skeleton.  The 
name "Silic - one" is made from Silic(on) + (Ket)one by dint of the fact 
that the basic skeleton is one of series of alternating Si and O atoms, 
giving the impression of a ketone-type linkage at the oxygens. Since 
Silicon has the same configuration of electrons in its outer shell as 
Carbon has, one might presume that its chemistry would be similar.  
However, it has a much larger diameter than carbon, so the repulsive 
forces between the nuclei prevent it from forming chains the way carbon 
can.  Interspersing oxygen molecules between the Silicons solves the 
problem.

  R     R     R  
  |     |     |   
-Si--O-Si--O-Si--O-
  |     |     |  
  R     R     R   

The "R"s represent either Hydrogens or hydrocarbon chains like the 
alkanes mentioned above. The basic silicone chain can be any where from a 
few to thousands of units long, and the huge variety of different side 
chains give the thousands of different "silicones" all their unique 
properties of viscosity, elasticity, adhesion etc.  The very simple ones, 
with hydrogens or methyl groups for the R's, and relatively short main 
chains are the ones known as silicone "oils" used as lubricants.  The 
ones used for glues, gaskets, sealants, breast implants etc are the more 
complex ones.

For those of you who hate organic chemistry, or who already knew all 
this, my apologies (of course, you probably stopped reading before now).

Tim Keenan
Noteworthy Piano Service
Terrace, BC.