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MARM 200336th Middle Atlantic Regional Meeting

American Chemical SocietyPrinceton University, June 8-11 2003

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McDonnell Hall

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Chlorine Rule

forBrmCln Compounds

Ray A. Gross, Jr.Prince George’s Community College

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Acknowledgements

• Junhua Yan’s Isotope Pattern Calculator http://www.geocities.com/junhuayan/pattern.htm (accessed May 2003).

• Instutute of Advanced Industrial Science and Technology; Tsukuba, Ibaraki, Japan

SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/ (accessed May 2003).

• NSF Grant: DUE-0202431

• Submitted to JCE

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Outline

• Compare molecular-ion clusters of real and ideal BrmCln compounds

• Discover a chlorine rule for BrmCln

compounds

• Apply the chlorine rule to three spectra

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1:1

1:2:1

(1:1)m

1:3:3:1

(3:1)n

3:1

9:6:1

Br1

Br2

Br3

Cl1

Cl2

Brm Cln

ideal compounds

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Ideal Model = Binomials

(a + b)m(3a + b)n

Br1Cl1

(1:1)1(3:1)1 = 3:4:1

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Br1Cl1Br Br

Br

Cl

Br

Cl

Br

Cl

Br

Cl

Br

Cl

Br

Cl

Br

Cl

Br

Cl

Chem. Educ. 2003, 8, 182-186

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Ideal Br1Cl2

(1:1)1(3:1)2 = 9:15:7:1

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Real = Calculated

Mass 288 289 290 291 292 293 294 295

% 61.8 6.8 100 11 45.3 5 6.4 0.7

Mass % Normalized 288 61.8 10 289 6.8 290 100.0 16 291 11.0 292 45.3 7 293 5.0 294 6.4 1 295 0.7

C10H19Br1Cl2

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Chlorine Constant

M +2 +4 +6 +8

3 10 12 6 13 11 13 6 1

Br3Cl1

M +2 +4 +6

3 7 5 13 7 5 1

M +2 +4

Br2Cl1

3 4 13 4 1

Br1Cl1

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M +2 +4 M +2 +4 +6 M +2 +4 +6 +8

3 4 13 4 1

9 15 7 110 16 7 1

27 54 36 10 130 59 38 10 1

Br1Cl1 Br1Cl2 Br1Cl3

Bromine Constant

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Chlorine Rule for Ideal Compounds

IM = 3n

When IM = 1, 3, 9, 27 or 81;

then

n = 0, 1, 2, 3, or 4, resp.

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240220

M = 224

220200 180170

Normal PatternEven M

m/z

M = 203

m/z

Normal PatternOdd M, contains N

Abnormal Pattern Strong M-1, M +1 peaks, etc. Contains aldehyde, etc.

M = 174

m/z

Cl

Br

Cl

NHCCH3

O

Cl

Cl CHO

Cl

Cl

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NH2

Cl

BrBr

3.3

283

283207 = Br2Cl1N1 76

16 224

Br

Cl

Cl9.9

224149 = Br1Cl2 75

17 174145

M - 29

9.6

CHO

Cl

Cl

174 99 = Cl2 + CHO 75

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Summary

• Find n in BrmCln from molecular-ion cluster

• Find m from number of cluster peaks

• Chlorine rule: a new tool for use in structure determinations