Bromine number
Encyclopedia
Bromine number is the amount of bromine
in grams absorbed by 100 grams (3.5 oz) of a sample. The number indicates the degree of unsaturation
.
The Bromine Number is useful as a measure of aliphatic unsaturation in gasoline
samples. The ARB
, in its Motor Vehicle Fuels Compliance Assistance Program, indicated that every unit of Bromine Number is equivalent to twice the percentage point of olefin content in gasoline. So, a gasoline with Bromine Number 30 would have an olefin content of not more than 15 vol%. One refinery compiled a year's worth of data on Bromine Number and the corresponding olefin content of gasoline. The data showed that the Bromine Number of gasoline is about 2.4 times the olefin content. A gasoline with Bromine Number of 30 would then have an olefin content of about 12.5 percent by volume, which is slightly lower than ARB's assumption, but still is higher than the CaRFG maximum limit of 10 percent by volume.
The Bromine Number is usually determined by electrochemical titration
, where bromine is generated in situ with the redox process of potassium bromide and bromate in an acidic solution, using a mercury catalyst to ensure the complete bromination of all olefins.
It is similar to I2 value and useful for oils containing fatty acids with conjugated system of double bonds.It can be calculated as an equivalent I2 value by multiplying result by:
At.Wt of I2/At.Wt of Br2 that is *126.9/79.9
ASTM method :
http://www.astm.org/Standards/D1492.htm
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
in grams absorbed by 100 grams (3.5 oz) of a sample. The number indicates the degree of unsaturation
Saturation (chemistry)
In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...
.
The Bromine Number is useful as a measure of aliphatic unsaturation in gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
samples. The ARB
California Air Resources Board
The California Air Resources Board, also known as CARB or ARB, is the "clean air agency" in the government of California. Established in 1967 in the Mulford-Carrell Act, combining the Bureau of Air Sanitation and the Motor Vehicle Pollution Control Board, CARB is a department within the...
, in its Motor Vehicle Fuels Compliance Assistance Program, indicated that every unit of Bromine Number is equivalent to twice the percentage point of olefin content in gasoline. So, a gasoline with Bromine Number 30 would have an olefin content of not more than 15 vol%. One refinery compiled a year's worth of data on Bromine Number and the corresponding olefin content of gasoline. The data showed that the Bromine Number of gasoline is about 2.4 times the olefin content. A gasoline with Bromine Number of 30 would then have an olefin content of about 12.5 percent by volume, which is slightly lower than ARB's assumption, but still is higher than the CaRFG maximum limit of 10 percent by volume.
The Bromine Number is usually determined by electrochemical titration
Titration
Titration, also known as titrimetry, is a common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of an identified analyte. Because volume measurements play a key role in titration, it is also known as volumetric analysis. A reagent, called the...
, where bromine is generated in situ with the redox process of potassium bromide and bromate in an acidic solution, using a mercury catalyst to ensure the complete bromination of all olefins.
It is similar to I2 value and useful for oils containing fatty acids with conjugated system of double bonds.It can be calculated as an equivalent I2 value by multiplying result by:
At.Wt of I2/At.Wt of Br2 that is *126.9/79.9
ASTM method :
http://www.astm.org/Standards/D1492.htm