Handbook of Solvents - George Wypych - ChemTech - Ventech!

1202 Margot Scheithauer
Solvents are volatile organic compounds as well as mixtures thereof at a boiling point
< 200°C, which under normal conditions (20°C and 1013 hPa) are liquid and are applied for
dissolving and diluting other substances without undergoing chemical change. 3
As can be seen, there are clear differences in the way VOCs are defined. 4 The most
general, and hence least disputable, one is:
Definition of volatile organic compounds according to DIN ISO 11890/1,2, 5,6
Solvent is generally any organic liquid and/or any organic solid substance, which
evaporates by itself under prevailing conditions (temperature and pressure).
Definition of VOC according to Council Directive 1999/13/EC 1
Volatile organic compound, VOC, shall mean any organic compound having at
293.15 K a vapor pressure of 0.01 kPa or more, or having a corresponding volatility under
the particular conditions of use. For the purpose of this Directive, the fraction of creosote,
which exceeds this value of vapor pressure at 293.15 K shall be considered as a VOC.
In the Lösemittelverordnung Österreichs (Austrian Regulations on Solvents) of
1995, 7 which on this issue corresponds to the österreichische Lackieranlagen-
Verordnung (Austrian Regulation on Varnishing Plants) of 1995, 8 VOCs have a maximum
boiling point of 200°C. Hence, the volatile compounds at a boiling point > 200°C are
not included. These comprise, e.g., some film forming media, such as butyldiglycol,
butyldiglycolacetate, and texanol. Similarly, reactive solvents are excluded from this regulation.
Definitions of VOCs in the USA according to ASTM D 3960-1 9
Volatile Organic Compound (VOC), means any compound of carbon, excluding carbon
monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium
carbonate, which participates in atmospheric photochemical reactions. This includes
any such organic compound other than the following, which have been determined to have
negligible photochemical reactivity: Methane; ethane; methylene chloride (dichloromethane);
1.1.1-trichloroethane (methyl chloroform); 1.1.1-trichloro-2.2.2-trifluorethane
(CFC-113), furthermore cyclic, branched or linear completely methylated siloxanes: acetone:
and perfluorocarbon compounds.
The regulatory definition under the control of the U.S. EPA may change.
Certain organic compounds that may be released under the specified bake conditions
are not classified as VOC as they do not participate in atmospheric photochemical reactions.
Such non-photochemically active compounds are referred to as exempt volatile compounds
in the practice.
An example of an exempt compound in the USA according to the EPA is tertiary-butyl-acetate
(TBA, B.p. of 98 °C). It is described as a substance not harmful in air. 10
Substances contained in air are differentiated in their mixtures according to their volatility:
11
Abbreviation Compound class Range of boiling point in °C
VVOC very volatile organic compounds < 0 up to 50 ÷ 100
VOC volatile organic compounds 50 ÷ 100 up to 250 ÷ 260
SVOC semi-volatile organic compounds 250 ÷ 260 up to 380 ÷ 500
TVOC means “total volatile organic compounds”.