Handbook of Solvents - George Wypych - ChemTech - Ventech!

3.2 Methods of solvent manufacture 69
AN =− 59. 9 + 1850 . E T
[3.1.3]
The donor number is frequently used in various fields of polymer chemistry (see Chapter
10). Another classification based on acidity/basicity of solvents allows the division of solvents
into six groups containing protic-neutral; protogenic; protophilic; aprotic-protophilic;
aprotic-protophobic; and aprotic-inert. 4
Snyder 5,6 developed classification of solvents for chromatography which arranges solvents
according to their chromatographic strength. It is classification based on the solvent’s
ability to engage in hydrogen bonding or dipole interaction using the experimentally determined
partition coefficients by Rohrschneider. 7 Eight groups of solvents were defined
based on cluster analysis. In addition to the usefulness of this classification in chromatography,
it was found recently that it is also useful in the design of coatings which do not affect
undercoated paints. 8
Numerous other classifications and sets of data are available, such as those included in
various databases on solvent toxicity, their environmental fate, combustion properties, explosive
limits, etc.
REFERENCES
1 Ch Reichardt, Solvents and Solvents Effects in Organic Chemistry, VCH, Weinheim, 1988.
2 V Gutman, G Resch, Lecture Notes on Solution Chemistry, Wold Scientific, Singapore, 1995.
3 G Gritzner, J. Mol. Liq., 73,74, 487-500 (1997).
4 Y Marcus, The Properties of Solvents, John Wiley & Sons, Chichester, 1999.
5 L R Snyder, J. Chromatographic Sci., 16, 223 (1978).
6 S C Rutan, P W Carr, J Cheong, J H Park, L R Snyder, J. Chromatography, 463, 21 (1989).
7 L Rohrschneider, Anal. Chem., 45, 1241 (1973).
8 I R Owen, US Patent 5,464,888, 3M, 1995.
3.2 OVERVIEW OF METHODS OF SOLVENT MANUFACTURE
George Wypych
ChemTec Laboratories, Inc., Toronto, Canada
Crude oil is the major raw material source for solvents. Aliphatic and aromatic
hydrocarbons are produced by physical processes used in petrochemical industry. Other
solvents are synthetic but their starting raw materials are usually products of the petrochemical
industry. Figure 3.2.1 shows the main groups of materials produced by petrochemical
industry from crude oil.
Two observations are pertinent: the main goal of petrochemical industry is to convert
crude oil to fuels. Solvents are only a small fraction of materials produced. Figure 3.2.2
shows that solvents are not only used directly as solvents but are also the building blocks in
the manufacture of a large number of materials produced by organic chemistry plants.
Desalting of crude oil is the first step in crude oil processing. It is designed to remove
corrosive salts which may cause catalyst deactivation. After desalting, crude oil is subjected
to atomospheric distillation. Figure 3.2.3 shows a schematic diagram of the crude oil distillation
process. The raw material is heated to 400 o C and separated into fractions on 30-50
fraction trays in distillation column. The diagram in Figure 3.2.3 shows the main fractions
obtained from this distillation. The heavier fraction cannot be distilled under atmospheric