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 butanoic acid

Interpreting the infrared spectrum of butanoic acid (butyric acid)

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 butanoic acid

infrared spectrum of butanoic acid C4H8O2 CH3CH2CH2COOH wavenumbers cm-1 functional group detection fingerprint pattern identification of butyric acid doc brown's advanced organic chemistry revision notes

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

Butanoic acid (butyric acid(c) doc b  (c) doc b  (c) doc b a carboxylic acid

Interpretation of the infrared spectrum of butanoic acid

The most prominent infrared absorption lines of butanoic acid

The hydroxyl O-H stretching vibration absorptions occur at wavenumbers 3300 to 2500 cm-1.

This is a broad series of bands due to interference from intermolecular hydrogen bonding between butanoic acid molecules - characteristic behaviour of carboxylic acids and any other molecule with a hydroxyl group.

One example of a hydrogen bond Oδ--Hδ+ǁǁǁ:Oδ- between butanoic acid molecules.

The O-H stretching vibrations overlap with C-H stretching vibrations, typically for alkyl groups at wavenumbers 2975 to 2845 cm-1 (so take care when looking for the presence of a hydroxyl group in a molecule).

The  C=O stretching vibration absorptions occur at wavenumbers 1725 to 1700 cm-1, characteristic of any molecule with a carbonyl group.

Although not unique, detection of these two groups in an infrared spectrum is indicative, but not proof, the molecule is a carboxylic acid e.g. the molecule could be a hydroxy-ketone!

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


Key words & phrases: C4H8O2 CH3CH2CH2COOH image and diagram explaining the infrared spectrum of butanoic acid, complete infrared absorption spectrum of butanoic acid, comparative spectra of butanoic acid, prominent peaks/troughs for identifying functional groups in the infrared spectrum of butanoic acid, important wavenumber values in cm-1 for peaks/troughs in the infrared spectrum of butanoic acid, revision of infrared spectroscopy of butanoic acid, fingerprint region analysis of butanoic acid, how to identify butanoic acid from its infrared spectrum, identifying organic compounds like butanoic acid from their infrared spectrum, how to analyse the absorption bands in the infrared spectrum of butanoic acid detection of carboxylic acid functional groups in the butanoic acid molecule example of the infrared spectrum of a molecule like butanoic acid with a carboxylic acid functional group  interpreting interpretation of the infrared spectrum of butanoic acid shows presence of carboxylic acid functional group formula type functional group butyric acid C4H8O2 CH3CH2CH2COOH


Links associated with butanoic acid

Organic chemistry Part ?

Infrared spectroscopy index

ALL SPECTROSCOPY INDEXES

All Advanced Organic Chemistry Notes

Use My Google search site box

Email doc b: chem55555@hotmail.com

TOP OF PAGE

 Doc Brown's Chemistry 

*

TOP OF PAGE

jobs and opportunities for teenagers best high street shop or best online deals currys pc consumer products computer deals world argos amazon internet deals for students john lewis hobbies and leisure products for teen years dell acer samsung raycon best selling footwear fashion bargains for teenagers bose sony asus huawei HP microsoft in-ear headphones earbuds downloadable games ipad desktop computer laptop computer for school college university students educational college university course opportunities for teenagers latest video games consoles apple iphone online download video games for teenagers google high end mobile phones cell phone bargain health products and advice for teenagers smartphone xiaomi computer laptops desktop pc deals for students oppo high tech products jewellery for teenage girls latest fashion in trainers personal care and beauty products for teenagers latest fashion in shoes best selling fashion clothes clothing bargains for teenagers latest fashion in mobile phones cell phones Nintendo games consoles internet music film entertainment deals subscriptions advice on teenage health conditions