MOLECULAR WEIGHTS OF TRI-, TETRA-  AND PENTACHLORO- ALKANES AND ALKENES

THE MOLECULAR WEIGHT DISCUSSED HERE IS THE ONE OBTAINED FROM ISOTOPICALLY AVERAGED ATOMIC WEIGHTS.

FOR ALKANES AND ALKENES WITH TRI-, TETRA, OR PENTA- CHLORO SUBSTITUTION, THE MOLECULAR WEIGHT IS CLOSE TO THE AVERAGE OF MAXMASS AND HIMAX1. THESE SPECTRAL PARAMETERS ARE DISCUSSED BELOW. IN 95% OF THESE CASES THE UPPER LIMIT FOR THE MOLECULAR WEIGHT IS WITHIN 52 DALTONS ABOVE THE AVERAGE. IN 99% OF THE COMPOUNDS THE UPPER LIMIT IS WITHIN 53 DALTONS ABOVE THE AVERAGE.

TYPES OF COMPOUNDS INCLUDED IN THESE UPPER LIMITS CONTAINED ONLY CARBON, HYDROGEN AND CHLORINE. THE LONGEST CARBON CHAIN HAD NINE MEMBERS. A FEW CYCLIC COMPOUNDS WERE INCLUDED. THE HIGHEST MOLECULAR WEIGHT OF ALL THESE COMPOUNDS WAS 238 DALTONS. 1,1,1,7-TETRACHLOROHEPTANE IS NOT INCLUDED IN THESE LIMITS. 

FOR A LOWER LIMIT TO THE MOLECULAR WEIGHT GO HERE.

MAXMASS-HIMAX1 AVERAGE

1. FIND THE HIGHEST MASS IN THE SPECTRUM WITH AN INTENSITY OF 5% OF THE BASE PEAK.  THIS IS DESIGNATED AS MAXMASS.

2. FIND THE HIGHEST MASS IN THE SPECTRUM WITH AN INTENSITY OF 1% OF THE BASE PEAK.  THIS IS CALLED HIMAX1.

3. TAKE THE AVERAGE OF THESE TWO MASSES. THEY MAY BE IDENTICAL, BUT HIMAX1 MUST BE GREATER THAN OR EQUAL TO MAXMASS.

SEE EXAMPLE BELOW

MAXMASS = 195 DALTONS

HIMAX1 = 195 DALTONS