Advanced Organic Chemistry: Infrared spectrum of 2,3-dimethylpentane

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Interpreting the infrared spectrum of 2,3-dimethylpentane

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 2,3-dimethylpentane

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Infrared spectroscopy - spectra index

See also comparing the 1H NMR and 13C NMR spectra of the nine alkane structural isomers of C7H16


Infrared 2,3-dimethylpentane spectra note: Students and teachers please note my explanation of the infrared spectrum of 2,3-dimethylpentane is designed for advanced, but pre-university, chemistry courses. Only the most prominent peaks for particular bond vibrations are discussed, particularly if 2,3-dimethylpentane has a functional group with a particular characteristic wavenumber peak.

C7H16 infrared spectrum of 2,3-dimethylpentane wavenumbers cm-1 functional group detection fingerprint pattern identification of 2,3-dimethylpentane doc brown's advanced organic chemistry revision notes 

Spectra obtained from a liquid film of 2,3-dimethylpentane. The right-hand part of the of the infrared spectrum of 2,3-dimethylpentane, wavenumbers ~1500 to 400 cm-1 is considered the fingerprint region for the identification of 2,3-dimethylpentane and most organic compounds. It is due to a unique set of complex overlapping vibrations of the atoms of the molecule of 2,3-dimethylpentane.

2,3-dimethylpentane C7H16 alkanes structure and naming (c) doc b alkanes structure and naming (c) doc b alkanes structure and naming (c) doc b

For more see The molecular structure, classification and naming of alkanes

Interpretation of the infrared spectrum of 2,3-dimethylpentane

The most prominent infrared absorption lines of 2,3-dimethylpentane

Strong C-H stretching vibration absorptions at wavenumbers 2940 to 2880 cm-1 for the CH2 and CH3 groups in 2,3-dimethypentane.

Several strong C-H deformation vibration absorptions at wavenumbers 1480 to 1365 cm-1 for the CH2 and CH3 groups in 2,3-dimethypentane.

There is a weak -CH- stretching vibration absorption at ~1340 cm-1.

Several strong C-C skeletal vibration absorptions associated with a C-(CH3)2 group occur at wavenumbers 840 to 790 and 1175 to 1140 cm-1.

There are no specific characteristic lines for alkanes like heptane because C-C and C-H vibrations are common to so many organic molecules and alkanes like 2,3-dimethypentane have no functional group that gives a characteristic vibration.

The absence of other specific functional group bands will show that a particular functional group is absent from the 2,3-dimethylpentane molecular structure.

Comparing the 1H NMR and 13C NMR spectra of the nine alkane structural isomers of C7H16

You can distinguish all 9 isomers from a data combination of their number of 1H NMR chemical shifts,

and their resulting integrated 1H proton ratios, plus, their number of 13C chemical shifts.

Name of the alkane structural isomer of molecular formula C7H16 Abbreviated structural formulae of the nine isomers of molecular formula C7H16 (interpretation complications with 3-methylhexane and 2,3-dimethylpentane because they exhibit R/S isomerism due to a chiral carbon) Skeletal formula of the nine alkane isomers of  molecular formula C7H16 Number of 1H NMR chemical shifts (δ) and proton ratio (links to spectrum) Number of 13C chemical shifts (δ) (links to spectrum)
heptane structural formula skeletal formula alkanes molecular structure naming (c) doc b heptane skeletal formula alkanes molecular structure naming (c) doc b 4 δ: proton ratio: 3:2:2:1 (6:4:4:2 in the molecule) 4 δ shifts
2-methylhexane structural formula skeletal formula alkanes molecular structure naming (c) doc b 2-methylhexane skeletal formula alkanes molecular structure naming (c) doc b 6 δ: proton ratio : 6:3:2:2:2:1 6 δ shifts
3-methylhexane structural formula skeletal formula alkanes molecular structure naming (c) doc b 3-methylhexane skeletal formula alkanes molecular structure naming (c) doc b 7 δ: proton ratio: 3:3:3:2:2:2:1 (simplification) ! 7 δ shifts
3-ethylpentane structural formula skeletal formula alkanes molecular structure naming (c) doc b 3-ethylpentane skeletal formula alkanes molecular structure naming (c) doc b 3 δ: proton ratio: 9:6:1 3 δ shifts
2,2-dimethylpentane structural formula skeletal formula alkanes molecular structure naming (c) doc b 2,2-dimethylpentane skeletal formula alkanes molecular structure naming (c) doc b 4 δ: proton ratio: 9:3:2:2 5 δ shifts
2,3-dimethylpentane structural formula skeletal formula alkanes molecular structure naming (c) doc b 2,3-dimethylpentane skeletal formula alkanes molecular structure naming (c) doc b 6 δ: proton ratio: 6:3:3:2:1:1 (simplification) ! 6 δ shifts (simplification) !!!
2,4-dimethylpentane structural formula skeletal formula alkanes molecular structure naming (c) doc b 2,4-dimethylpentane skeletal formula alkanes molecular structure naming (c) doc b 3 δ: proton ratio: 12:2:2 3 δ shifts
3,3-dimethylpentane structural formula skeletal formula alkanes molecular structure naming (c) doc b 3,3-dimethylpentane skeletal formula alkanes molecular structure naming (c) doc b 3 δ: proton ratio: 3:3:2 (6:4:4 in the molecule) 4 δ shifts
2,2,3-trimethylbutane structural formula skeletal formula alkanes molecular structure naming (c) doc b 2,2,3-trimethylbutane skeletal formula alkanes molecular structure naming (c) doc b 3 δ: proton ratio: 9:6:1 4 δ shifts

Key words & phrases: C7H16 image and diagram explaining the infrared spectrum of 2,3-dimethylpentane, complete infrared absorption spectrum of 2,3-dimethylpentane, comparative spectra of 2,3-dimethylpentane, prominent peaks/troughs for identifying functional groups in the infrared spectrum of 2,3-dimethylpentane, important wavenumber values in cm-1 for peaks/troughs in the infrared spectrum of 2,3-dimethylpentane, revision of infrared spectroscopy of 2,3-dimethylpentane, fingerprint region analysis of 2,3-dimethylpentane, how to identify 2,3-dimethylpentane from its infrared spectrum, identifying organic compounds like 2,3-dimethylpentane from their infrared spectrum, how to analyse the absorption bands in the infrared spectrum of 2,3-dimethylpentane detection of no functional groups in the 2,3-dimethylpentane molecule example of the infrared spectrum of a molecule like 2,3-dimethylpentane with no functional group  interpreting interpretation of the infrared spectrum of 2,3-dimethylpentane shows presence of no functional groups (CH3)2CHCH(CH3)CH2CH3 Diagram of absorption of wavenumber peaks in the infrared spectrum of 2,3-dimethylpentane. Characteristic peak wavenumbers in the infrared spectrum of 2,3-dimethylpentane. Finger print identification pattern using the infrared spectrum of 2,3-dimethylpentane. Revision notes on the infrared spectrum of 2,3-dimethylpentane. Matching and deducing the structure of the 2,3-dimethylpentane molecule from  its infrared spectrum. Infrared spectroscopy of aliphatic alkanes, infrared spectra of 2,3-dimethylpentane, a structural isomer of molecular formula C7H16 How do you interpret the infrared absorption spectrum of  2,3-dimethylpentane How to interpret the infrared spectrum of  2,3-dimethylpentane Explanatory diagram of the infrared spectrum of the  2,3-dimethylpentane molecule in terms of its molecular structure. Listing data of the prominent main wavenumber peaks troughs in the infrared spectrum of  2,3-dimethylpentane. How to explain the infrared spectrum of  2,3-dimethylpentane. Use of the infrared spectrum of  2,3-dimethylpentane, identification of  2,3-dimethylpentane from its infrared spectrum - fingerprint wavenumber pattern to identify the  2,3-dimethylpentane molecule. The uses of the infrared spectrum of the  2,3-dimethylpentane molecule. The distinctive features of the infrared spectrum of the  2,3-dimethylpentane molecule explained interpretation diagram explaining the peaks-trough of the transmittance of the infrared spectrum of  2,3-dimethylpentane what does the infrared spectrum tell you about the structure and properties of the  2,3-dimethylpentane molecule? How is infrared spectrum of  2,3-dimethylpentane used to identify  2,3-dimethylpentane?


Links associated with 2,3-dimethylpentane

The mass spectrum of 2,3-dimethylpentane

The H-1 NMR spectrum of 2,3-dimethylpentane

The C-13 NMR spectrum of 2,3-dimethylpentane

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Infrared spectroscopy index

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Infrared spectra of the isomers of C7H16

The infrared spectrum of heptane

The infrared spectrum of 2-methylhexane

The infrared spectrum of 3-methylhexane

The infrared spectrum of 3-ethylpentane

The infrared spectrum of 2,2-dimethylpentane

The infrared spectrum of 2,3-dimethylpentane

The infrared spectrum of 2,4-dimethylpentane

The infrared spectrum of 3,3-dimethylpentane

The infrared spectrum of 2,2,3-trimethylbutane

Mass spectra of the isomers of C7H16

The mass spectrum of heptane

The mass spectrum of 2-methylhexane

The mass spectrum of 3-methylhexane

The mass spectrum of 3-ethylpentane

The mass spectrum of 2,2-dimethylpentane

The mass spectrum of 2,3-dimethylpentane

The mass spectrum of 2,4-dimethylpentane

The mass spectrum of 3,3-dimethylpentane

The mass spectrum of 2,2,3-trimethylbutane

1H NMR spectra of the isomers of C7H16

The H-1 NMR spectrum of heptane

The H-1 NMR spectrum of 2-methylhexane

The H-1 NMR spectrum of 3-methylhexane

The H-1 NMR spectrum of 3-ethylpentane

The H-1 NMR spectrum of 2,2-dimethylpentane

The H-1 NMR spectrum of 2,3-dimethylpentane

The H-1 NMR spectrum of 2,4-dimethylpentane

The H-1 NMR spectrum of 3,3-dimethylpentane

The H-1 NMR spectrum of 2,2,3-trimethylbutane

13C NMR spectra of the isomers of C7H16

The C-13 NMR spectrum of heptane

The C-13 NMR spectrum of 2-methylhexane

The C-13 NMR spectrum of 3-methylhexane

The C-13 NMR spectrum of 3-ethylpentane

The C-13 NMR spectrum of 2,2-dimethylpentane

The C-13 NMR spectrum of 2,3-dimethylpentane

The C-13 NMR spectrum of 2,4-dimethylpentane

The C-13 NMR spectrum of 3,3-dimethylpentane

The C-13 NMR spectrum of 2,2,3-trimethylbutane

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