Boiling point of ethers and alkanes

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SUMMARY

Ethers typically exhibit higher boiling points than alkanes due to dipole-dipole interactions; however, this rule does not universally apply, particularly with larger alkanes. For instance, hexane has a higher boiling point than ethyl-propyl ether, and diethyl ether surpasses pentane in boiling point. The increase in boiling point for alkanes is attributed to enhanced Van der Waals interactions as the carbon chain lengthens. This indicates that while the general principle holds, exceptions arise with larger hydrocarbons.

PREREQUISITES
  • Understanding of organic chemistry principles, particularly boiling point determinants
  • Familiarity with dipole-dipole interactions and Van der Waals forces
  • Knowledge of alkane and ether structures and their properties
  • Basic grasp of molecular size effects on physical properties
NEXT STEPS
  • Research the boiling point trends of various ethers and alkanes
  • Explore the impact of molecular branching on boiling points
  • Study the role of intermolecular forces in determining physical properties
  • Investigate the boiling points of larger alkanes with varying structures
USEFUL FOR

Chemistry students, organic chemists, and anyone interested in the physical properties of organic compounds, particularly those studying boiling point variations in ethers and alkanes.

Queequeg
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My organic chemistry textbook says that ethers generally have higher boiling points than alkanes because of dipole-diole interactions, but why then does hexane have a higher boiling point than ethyl-propyl-ether? Is this principle then not true for larger alkanes with 5 or more carbons? Diethyl ether also has a higher boiling point than pentane, but then butane has a higher B.P than ethyl methyl ether.
 
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2 reasons:

1) As an alkane or alkyl gets longer but does not branch, its BP increases b/c it can have more Van der Waals interactions; thus, ethyl-propyl-ether has a higher bp than ethyl methyl ether;;; hexane has a higher BP than pentance, etc. hope this helps.
 
Queequeg said:
My organic chemistry textbook says that ethers generally have higher boiling points than alkanes because of dipole-diole interactions

IMHO "generally" suggests it is just a rule of thumb, and as such can often fail.
 

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