Wednesday, June 17, 2020

Name of refrigerant significance(R22,R134A)

The prefix describes what kinds of atoms are in a particular molecule, the next step is to calculate the number of each type of atom. The key to the code is to add 90 to the number; the result shows the number of C, H, and F atoms. For HCFC-141b:

One more piece of information is needed to decipher the number of Cl atoms. All of these chemicals are saturated; that is, they contain only single bonds. The number of bonds available in a carbon-based molecule is 2C + 2. Thus, for HCFC-141b, which has 2 carbon atoms, there are 6 bonds. Cl atoms occupy bonds remaining after the F and H atoms. So HCFC-141b has 2C, 3H, 1F, and 2Cl:

First, consider two-carbon molecules. For example, HCFC-141, HCFC-141a, and HCFC-141b all have the same atoms (2C, 3H, 1F, and 2Cl), but they are organized differently. To determine the letter, total the atomic weights of the atoms bonded to each of the carbon atoms. The arrangement that most evenly distributes atomic weights has no letter. The next most even distribution is the "a" isomer, the next is "b," etc. until no more isomers are possible.

A common way of writing isomers' structure is to group atoms according to the carbon atom with which they bond. Thus, the isomers of HCFC-141 are:

  • HCFC-141  :   CHFCl - CH2Cl (atomic weights on the 2 carbons = 37.5 and 55.5)
  • HCFC-141a:   CHCl2 - CH2F (atomic weights on the 2 carbons = 21 and 72)
  • HCFC-141b:   CFCl2 - CH3 (atomic weights on the 2 carbons = 3 and 90)

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