propylamine low high resolution 1H proton nmr spectrum of propanaamine analysis interpretation of chemical shifts ppm spin spin line splitting doc brown's advanced organic chemistry revision notes

Advanced Organic Chemistry: H-1 NMR spectrum of propylamine CH₃CH₂CH₂NH₂

HOME PAGE * SEARCH * GCSE Level Chemistry age ~14-16 * Advanced Level Chemistry age ~16-19

Interpreting and explaining the H-1 hydrogen-1 (proton) NMR spectrum of propylamine (1-aminopropane, propan-1-amine, 1-propylamine)

[Author © Dr Phil Brown PhD: Doc Brown's advanced level organic chemistry exam revision notes suitable for students of UK A level chemistry courses & US K12 grade 11, grade 12 and AP honors chemistry courses: Molecular spectroscopy analysis of propylamine (propanamine) [spectra updated Mar 28th 2026 *]

Email doc brown re-edit 1H NMR spectrum of CH₃CH₂CH₂NH₂

Links associated with propylamine * [privacy policy, cookies and disclaimer]

This is a BIG chemistry website, PLEASE take time to explore it

H-1 proton NMR spectroscopy - spectra index

Introductory note on the 1H NMR spectra of propylamine

Students and teachers please note my explanation of the proton NMR spectrum of propylamine is designed for advanced, but pre-university, chemistry courses.

The chemical shift δ splitting pattern effects for propylamine are confined to a proton spin-spin coupling effects analysed using the n+1 rule for adjacent non-equivalent proton fields (n is the number of neighbouring protons in a non-equivalent different chemical environment for the propylamine molecule).

It is assumed that the integrated intensities of the ¹H NMR δ chemical shifts give the ratio of the protons in the different non-equivalent chemical environments of the propylamine molecule.

The most common solvent used for investigating the 1H NMR spectrum of compounds like propylamine, is CDCl₃ and other deuterated solvents to avoid confusion with a ¹H NMR signal, ²D (²H) has a different NMR chemical shift.

low and high resolution H-1 proton nmr spectrum of propylamine analysis interpretation of chemical shifts ppm spin spin line splitting diagram doc brown's advanced organic chemistry revision notes

TMS is the acronym for tetramethylsilane, formula Si(CH₃)₄, whose protons are arbitrarily given a chemical shift of 0.0 ppm. This is the 'standard' in ¹H NMR spectroscopy and all other proton shifts, called chemical shifts, depend on the individual (electronic) chemical environment of the hydrogen atoms in an organic molecule - propylamine here.

The chemical shifts quoted in ppm on the diagram of the H-1 NMR spectrum of propylamine represent the peaks of the intensity of the chemical shifts of (which are often groups of split lines at high resolution) AND the relative integrated areas under the peaks gives you the ratio of protons in the different chemical environments of the propylamine molecule.

propylamine, (1-aminopropane), C₃H₉N, , ,

The classification, structure and naming of organic nitrogen compounds

Interpreting the H-1 NMR spectrum of propylamine

For relatively simple molecules, the low resolution H-1 NMR spectrum of propylamine is a good starting point.

The hydrogen atoms (protons) of propylamine occupy four different chemical environments so that the low resolution NMR spectra should show four peaks of different H-1 NMR chemical shifts (diagram above for propylamine).

CH₃CH₂CH₂NH₂

(Note the ratio 3:2:2:2 of the four colours of the protons in the four chemically different environments)

Although there are 9 hydrogen atoms in the molecule, there are only 4 possible chemical environment for the hydrogen atoms of propylamine, so four ¹H NMR peaks.

The proton ratio 3:2:2:2 observed, corresponds with the structural formula of propylamine.

As you can see, the high resolution spectrum of propylamine is complex

So, using the chemical shifts and applying the n+1 rule to propylamine,

BUT the protons attached to the nitrogen atom do not usually cause a resonance splitting effect on protons on an adjacent carbon, and neither is their resonance split by adjacent carbon atom protons.

Chemical shift (a) methyl protons (blue)

(a) At a chemical shift of 0.92 ppm the CH₃ protons are split by the adjacent CH₂ protons into a 1:2:1 triplet in terms of intensities (theoretically), n+2 = 3.

Evidence for the presence of a CH₂ group in the molecule of propylamine

CH₃CH₂CH₂NH₂

Chemical shift (b) CH₂ protons (purple)

(b) The 1.45 ppm chemical shift:

From the n+1 rule, the 'left-hand' CH₂ protons (H₂) are split by CH₃ protons (H₃) and by the 'right-hand' CH₂ protons (H₂), (5 protons in total), into a 1:5:10:10:5:1 sextet of resonance lines (n+5 = 6).

This is pattern of resonances is a good indication of a propyl group (CH₃CH₂CH₂).

CH₃CH₂CH₂NH₂

(c) Chemical shift (c) CH₂ protons (green)

The 2.65 ppm chemical shift:

The 'right-hand' CH₂ protons (H₂) resonances are split by the left CH₂ protons (H₂) into a 1:2:1 triplet of resonance lines (n+2 = 3). No splitting due to the NH₂ protons.

CH₃CH₂CH₂NH₂

(d) Chemical shift (d) NH₂ protons (brown)

The 1.24 ppm chemical shift:

The amine group proton resonance is not split by the adjacent CH₂ protons, so appears a singlet.

The lack of resonance splitting is due to exchange of protons between the amine group of the amine molecules which inhibits the coupling between amine group protons and any adjacent alky group protons - even a trace of water catalyses this effect.

This chemical shift is also dependent on the solvent used.

EXTRA NOTE on why the NH proton chemical shift is usually observed as a singlet in amines like propylamine and how deuterium oxide can be used to identify the peak caused by the amine protons

Although extremely weak bases, there is constant exchanging of protons between amine molecules (R = alkyl groups of propylamine) particularly if a trace of water is present.

R-N-H₂ + R-N-H₂ R-N-HH + R-N-HH

R-N-H₂ + H-O-H R-N-HH + H-O-H

This cannot happen with the non-acidic C-H protons of alkyl groups in amines like propylamine.

This rapid proton transfer interferes with the field splitting effects of the amine N-H protons and carbon C-H protons and the spin-spin coupling effects disappears if enough deuterium oxide is present.

This phenomena can be used to identify the N-H proton resonance in amines from other C-H proton resonances in amine molecules like propylamine.

If deuterium oxide (D₂O, where D = ²H) is added to the NMR amine sample, the ¹H protons are rapidly replaced by ²H protons in the propylamine molecule.

R-N-H₂ + D-O-D R-N-D₂ + H-O-H

The ²H chemical shift frequency is different to the ¹H chemical shift frequency, so the effect of D₂O is to remove (or reduce intensity of) the chemical shift for the NH proton from the ¹H NMR spectrum of propylamine, thereby identifying the original ¹H chemical shift as belonging to the amine group N-H protons and not a C-H proton of the propylamine molecule.

The splitting pattern from proton spin-spin coupling effects is analysed using the n+1 rule for adjacent non-equivalent proton fields (n is the number of neighbouring protons in a non-equivalent different chemical environment) and applied to the ¹H NMR spectrum of propylamine.

Number of protons ¹H causing splitting	Splitting pattern produced from the n+1 rule and the theoretical ratio of line intensities
0 means no splitting							1
1 creates a doublet						1		1
2 creates a triplet					1		2		1
3 creates a quartet				1		3		3		1
4 creates a quintet			1		4		6		4		1
5 creates a sextet		1		5		10		10		5		1
6 creates a septet	1		6		15		20		15		6		1

Key words & phrases: Interpreting the proton H-1 NMR spectra of propylamine, low resolution & high resolution proton nmr spectra of propylamine, H-1 nmr spectrum of propylamine, understanding the hydrogen-1 nmr spectrum of propylamine, explaining the line splitting patterns in the high resolution H-1 nmr spectra of propylamine, revising the H-1 nmr spectrum of propylamine, proton nmr of propylamine, ppm chemical shifts of the H-1 nmr spectrum of propylamine, explaining and analyzing spin spin line splitting in the H-1 nmr spectrum, how to construct the diagram of the H-1 nmr spectrum of propylamine, how to work out the number of chemically different protons in the structure of the propylamine organic molecule, how to analyse the chemical shifts in the hydrogen-1 H-1 proton NMR spectrum of propylamine using the n+1 rule to explain the spin - spin coupling ine splitting in the proton nmr spectrum of propylamine deducing the nature of the protons from the chemical shifts ppm in the H-1 nmr spectrum of propylamine other names 1-aminopropane n-propylamine 1-propanamine 1-propylamine How do you interpret the H-1 NMR spectrum of propylamine How to interpret the H-1 NMR spectrum of propylamine Explanatory diagram of the chemical shifts of the 1H H-1 proton NMR spectrum of the propylamine molecule in terms of its molecular structure. Listing data of all the chemical shift peaks in ppm in the proton NMR spectrum of propylamine. How to explain the H-1 NMR spectrum of propylamine. The chemical shifts and integrated values of the proton ratios in the 1-H NMR spectrum of the propylamine molecule. How to work out the molecular structure of the propylamine molecule from its proton NMR spectrum. The uses and distinctive features of the proton NMR spectrum of the propylamine molecule explained. What does the H-1 proton NMR spectrum chemical shifts tell us about the structure and properties of the propylamine molecule? explaining the spin-spin proton coupling effects in the 1H NMR spectrum of propylamine. interpretation diagram explaining the proton splitting pattern produced from the n+1 rule and the theoretical ratio of chemical shift δ and values of intensities for the proton NMR spectrum lines of propylamine

Links associated with propylamine

The infrared spectrum of propylamine (propan-1-amine, 1-aminopropane)

The mass spectrum of propylamine (propan-1-amine, 1-aminopropane)

The C-13 NMR spectrum of propylamine (propan-1amine, 1-aminopropane)

The chemistry of ORGANIC NITROGEN COMPOUNDS revision notes INDEX

H-1 proton NMR spectroscopy index (Please read 8 points at the top of the ¹H NMR index page)

ALL SPECTROSCOPY INDEXES

All Advanced Organic Chemistry Notes

Use My Google search site box

Email doc b: chem55555@hotmail.com

Website content © Dr Phil Brown 2000+. All copyrights reserved on revision notes, images, quizzes, worksheets etc. Copying of Doc Brown's pre-university advanced level chemistry website material is NOT permitted. Exam revision summaries & references to science course specifications are unofficial. These organic chemistry revision notes on spectroscopy (on the 1H NMR spectrum of propylamine, propanamine, propan-1-amine, 1-propylamine, 1-propanamine) are suitable for use of pre-university students studying AQA advanced level chemistry, Edexcel advanced level chemistry, OCR advanced level chemistry, IB advanced level chemistry, WJEC (Eduqas) advanced level chemistry, CIE advanced level chemistry, CCEA advanced level chemistry, US grade 11-12 AP honors chemistry courses and they will also prove useful to 1st year undergraduate students of chemistry.