HOME PAGE * KS3 SCIENCES * GCSE BIOLOGY CHEMISTRY PHYSICS * ADVANCED LEVEL CHEMISTRY

SPECTROSCOPY INDEXES  *  All Advanced Organic Chemistry Notes  *  [SEARCH BOX]

Advanced Organic Chemistry: Infrared spectrum of propene ('propylene')

Scroll down and take time to study the content and/or follow links or [Use the website search box]

Interpreting the infrared spectrum of propene ('propylene')

Doc Brown's Chemistry Advanced Level Pre-University Chemistry Revision Study Notes for UK IB KS5 A/AS GCE advanced A level organic chemistry students US K12 grade 11 grade 12 organic chemistry courses involving molecular spectroscopy analysing infrared spectra of propene

email doc brown

Use your mobile phone or ipad etc. in 'landscape' mode

This is a BIG website, you need to take time to explore it

Infrared spectroscopy - spectra index

See also comparing the infrared, mass, 1H NMR and 13C NMR spectra of propane, cyclopropane and propene

infrared spectrum of propene C3H6 CH3CH=CH2 wavenumbers cm-1 functional group detection fingerprint pattern identification of propene doc brown's advanced organic chemistry revision notes 

Spectra obtained from a liquid film of propene. The right-hand part of the of the infrared spectrum of propene, wavenumbers ~1500 to 400 cm-1 is considered the fingerprint region for the identification of propene and most organic compounds. It is due to a unique set of complex overlapping vibrations of the atoms of the molecule of propene.

Propene, alkenes structure and naming (c) doc b, alkenes structure and naming (c) doc b, alkenes structure and naming (c) doc b, alkenes structure and naming (c) doc b, alkenes structure and naming (c) doc b, alkenes structure and naming (c) doc b

Interpretation of the infrared spectrum of propene

The most prominent infrared absorption lines of propene

There are prominent bands of C-H stretching vibration absorptions peaking at wavenumbers ~3095 to 3010 cm-1, and also 995 to 905 cm-1, associated with the C-H bond in a RCH=CH2 grouping e.g. as in propene.

Overlapping with the above, are prominent bands due to C-H stretching vibration absorptions peak at wavenumbers ~2975 to 2860 cm-1, typical of molecules with a methyl alkyl group.

There is a very strong characteristic absorption for C=C stretching vibrations, peaking at wavenumbers 1645 to 1640 cm-1, typical of an alkene like propene.

Around wavenumbers ~1470 to 1370 cm-1 are absorptions dues to C-H deformation vibrations of the C-CH3 grouping in propene.

The absence of other specific functional group bands will show that a particular functional group is absent from the propene molecular structure.

Comparing the infrared, mass, 1H NMR and 13C NMR spectra of propane, cyclopropane and propene

NOTE: The images are linked to their original detailed spectral analysis pages AND can be doubled in size with touch screens to increase the definition to the original ethane and ethene image sizes.

Comparing the infrared spectra of propane, propene and cyclopropane.

Cyclopropane and propene are structural isomers of molecular formula C3H6.

Propane and propene exemplify the infrared spectra of lower members of  the alkane and alkene homologous series of CnH2n+2 and CnH2n hydrocarbon molecules where n = 3.

INFRARED SPECTRA (above): Apart from the significant differences in the fingerprint region at wavenumbers 1500 to 400 cm-1, the most striking differences are: (i) propene shows the characteristic absorption at ~1700 cm-1 for the C=C stretching vibrations, absent in the other two spectra, (ii) cyclopropane shows an absorption band at 2200 cm-1, absent in the other two spectra, (iii) propane has an absorption band at ~750 cm-1, absent in the other two spectra.

Comparing the mass spectra of propane, propene and cyclopropane.

Cyclopropane and propene are structural isomers of molecular formula C3H6.

Propane and propene exemplify the mass spectra of lower members of  the alkane and alkene homologous series of CnH2n+2 and CnH2n hydrocarbon molecules where n = 3.

MASS SPECTRA (above): All three hydrocarbons show some similarities in their mass spectra e.g. m/z ions 26 to 28 for [C2Hx]+ (x = 2 to 4) and m/z 14 and 15 ions - but these are found in most aliphatic hydrocarbon spectra. The molecular ion peaks will be the same for the isomeric propene and cyclopropane (m/z 42) but that of propane will be 2 mass units higher at m/z 44. The base ion peak m/z values are all different, propane 29, propene 41 and cyclopropane 42.

Comparing the 1H proton NMR spectra of propane, propene and cyclopropane.

Cyclopropane and propene are structural isomers of molecular formula C3H6.

Propane and propene exemplify the 1H proton NMR spectra of lower members of  the alkane and alkene homologous series of CnH2n+2 and CnH2n hydrocarbon molecules where n = 3.

1H NMR SPECTRA (above): The 1H NMR spectra of all three molecules give different proton ratios i.e. propane 3:1 (actually 6:2 in the molecule), propene 2:1:3 (spectrum and molecule) and cyclopropane just a singlet for the six protons, so all three can be distinguished from each other by their 1H NMR spectra..

Comparing the carbon-13 NMR spectra of propane, propene and cyclopropane.

Cyclopropane and propene are structural isomers of molecular formula C3H6.

Propane and propene exemplify the carbon-13 NMR spectra of lower members of  the alkane and alkene homologous series of CnH2n+2 and CnH2n hydrocarbon molecules where n = 3.

13C NMR SPECTRA (above): The 13C NMR spectra of the three molecules show different numbers of carbon-13 chemical environments i.e propane 2, propene 3 and cyclopropane only 1, so all three could be distinguished from each other.

Key words & phrases: C3H6 H2C=CHCH3 CH3CH=CH2 CH2=CHCH3 image and diagram explaining the infrared spectrum of propene, complete infrared absorption spectrum of propene, comparative spectra of propene, prominent peaks/troughs for identifying functional groups in the infrared spectrum of propene, important wavenumber values in cm-1 for peaks/troughs in the infrared spectrum of propene, revision of infrared spectroscopy of propene, fingerprint region analysis of propene, how to identify propene from its infrared spectrum, identifying organic compounds like propene from their infrared spectrum, how to analyse the absorption bands in the infrared spectrum of propene detection of alkene functional groups in the propene molecule example of the infrared spectrum of a molecule like propene with a alkene functional group  interpreting interpretation of the infrared spectrum of propene shows presence of alkene functional group  alkene functional group propylene Diagram of absorption of wavenumber peaks in the infrared spectrum of propene. Characteristic peak wavenumbers in the infrared spectrum of propene. Finger print identification pattern using the infrared spectrum of propene. Revision notes on the infrared spectrum of propene. Matching and deducing the structure of the propene molecule from  its infrared spectrum.


Links associated with propene

The chemistry of ALKENES revision notes INDEX

The mass spectrum of propene ('propylene')

The H-1 NMR spectrum of propene ('propylene')

The C-13 NMR spectrum of propene ('propylene')

Infrared spectroscopy index

ALL SPECTROSCOPY INDEXES

All Advanced Organic Chemistry Notes

Use My Google search site box

Email doc b: chem55555@hotmail.com

 Doc Brown's Chemistry 

*

TOP OF PAGE