Bayer's Strain theory - And Its Limitations - organic chemistry -2nd

Strain Theory - Pharmaceutical Organic Chemistry -II
3rd Sem B pharmacy.

1. DNCOP JAMGAON,SINNAR,NASIK SESSION : 202 2 -202 3 COURSE : B PHARMA YEAR : 2nd SEMESTER : 4th SUBJECT : PHARMACEUTICAL ORGANIC CHEMISTRY - II TOPIC : BAEYER’S STRAIN THEORY AND ITS LIMITATIONS REPRESENTED BY: - Purushottam Mali Roll No - 60

2. ACKNOWLEDGEMENT I would like to express my special thanks of gratitude to our pharmaceutical organic chemistry-II professor respected “ Mrs. Bhagyashree Mam” ma'am who gave us the golden opportunity to do this wonderful presentation on topic ‘‘ Baeyer’s theory and its limitations”

3. CONTENT 1. INTRODUCTION OF BAEYER’S STRAIN THEORY 2. ASSUMPTION OF BAEYER’S STRAIN THEORY 3. LIMITATIONS OF BAEYER’S STRAIN THEORY 4. CASE STUDY ON BAEYER’S STRAIN THEORY 5. REFERENCES

4. INTRODUCTION OF BAEYER’S STRAIN THEORY 4. He assumes that all the cyclo -alkanes are fiat and coplanar that means they are two dimensional and present in one plane. Adolf von Baeyer, a German chemist and a Nobel prize winner from university of Munich, Germany in 1885 proposed a theory to explain the relative stability of the first few cycloalkane. The theory based on following facts: 1. Cyclo -alkanes are saturated compounds. So, all the carbons should have normal tetrahedral angle of 109.5° 2. Any deviation of bond angles from the normal tetrahedral value would, impose a condition of internal strain on the ring called angle strain. 3. More the value of angle strain less stable the compound is.

5. ASSUMPTIONS OF BAEYER’S STRAIN THEORY • All ring systems are planar. Deviation from normal tetrahedral angles results in to instable cycloalkanes. • The large ring systems involve negative strain hence do not exists. • The bond angles in cyclohexane and higher cycloalkanes ( cycloheptane , cyclooctane , cyclononane , etc.) are not larger than 109.5° because the carbon rings of those compounds are not planar (flat).

6. LIMITATIONS OF BAEYER’S STRAIN THEORY • Baeyer was not able to explain the effect of angle strain in larger ring systems. • According to Baeyer Cyclopentane should be much stable than cyclohexane but practically it is reversed. • Larger ring systems are not possible according to Baeyer as they have negative strain but they exist and much stable. • Larger ring systems are not planar but wrinkled (puckered) to eliminate angle strain.

7. CASE STUDY ON BAEYER’S STRAIN THEORY According to Baeyer, the relative order of stability tor some common cycloalkanes is as under: Cyclopentane > Cyclohexane > Cyclobulane > Cyclopropane Actual observed order of stability for these cycloalkanes is as under: Cyclohexane > Cyclopentane > Cyclobutane > Cyclopropane

8. CASE STUDY ON BAEYER’S STRAIN THEORY According to Baeyer, the relative order of stability tor some common cycloalkanes is as under: Cyclopentane > Cyclohexane > Cyclobulane > Cyclopropane Actual observed order of stability for these cycloalkanes is as under: Cyclohexane Cyclopentane Cyclobutane Cyclopropane

9. REFERENCES • https ://staticscience.com • http://www.researchgate.net THANK YOU 😀