Morpholine

Not to be confused with morphine or morpholino.

Morpholine
IUPAC name morpholine
Other names Diethylenimide Oxide 1,4-oxazinane tetrahydro-1,4-oxazine
Identifiers
CAS number	110-91-8 Y
UNII	8B2ZCK305O N
KEGG	C14452 N
ChEMBL	CHEMBL276518 N
RTECS number	QD6475000
Jmol-3D images	Image 1
SMILES O(CCNC1)C1
Properties
Molecular formula	C4H9NO
Molar mass	87.1 g/mol
Appearance	Colorless liquid
Density	1.007 g/cm3
Melting point	-5 °C, 268 K, 23 °F
Boiling point	129 °C, 402 K, 264 °F
Solubility in water	miscible
Acidity (pKa)	8.36[1]
Hazards
MSDS	Oxford MSDS
R-phrases	R10 R20/21/22 R34
S-phrases	(S1/2) S23 S36 S45
Main hazards	Flammable, Corrosive
NFPA 704	3 3 1
Flash point	31 °C
Autoignition temperature	275 °C
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Morpholine is an organic chemical compound having the chemical formula O(CH₂CH₂)₂NH. This heterocycle, pictured at right, features both amine and ether functional groups. Because of the amine, morpholine is a base; its conjugate acid is called morpholinium. For example, neutralizing morpholine with hydrochloric acid makes the salt morpholinium chloride.

Production

Morpholine may be produced by the dehydration of diethanolamine with sulfuric acid:^[2]

Uses

Industrial applications

Morpholine is a common additive, in parts per million concentrations, for pH adjustment in both fossil fuel and nuclear power plant steam systems. Morpholine is used because its volatility is about the same as water, so once it is added to the water, its concentration becomes distributed rather evenly in both the water and steam phases. Its pH adjusting qualities then become distributed throughout the steam plant to provide corrosion protection. Morpholine is often used in conjunction with low concentrations of hydrazine or ammonia to provide a comprehensive all-volatile treatment chemistry for corrosion protection for the steam systems of such plants. Morpholine decomposes reasonably slowly in the absence of oxygen at the high temperatures and pressures in these steam systems.

Organic synthesis

Morpholine undergoes most chemical reactions typical for other secondary amines, though the presence of the ether oxygen withdraws electron density from the nitrogen, rendering it less nucleophilic (and less basic) than structurally similar secondary amines such as piperidine. For this reason, it forms a stable chloramine (CAS#23328-69-0).^[3]

It is commonly used to generate enamines.^[4]

Morpholine is widely used in organic synthesis. For example, it is a building block in the preparation of the antibiotic linezolid and the anticancer agent gefitinib (Iressa).

In research and in industry, the low cost and polarity of morpholine lead to its common use as a solvent for chemical reactions.

Producers

Most (as above) is widespread in Europe and the USA; accordingly, producers in Europe and the USA are able to cover the domestic and export markets.

Agriculture

As a fruit coating

Morpholine is used as a chemical emulsifier in the process of waxing fruit. Naturally, fruits make waxes to protect against insects and fungal contamination, but this can be lost as the fruit is cleaned. A small amount of new wax is applied to replace it. Morpholine is used as an emulsifier and solubility aid for shellac, which is used as a wax for fruit coating.^[5]

As a component in fungicides

Morpholine derivatives used as agricultural fungicides in cereals are known as ergosterol biosynthesis inhibitors.

• Amorolfine
• Fenpropimorph
• Tridemorph

References

1. ^ Hall, H.K., J. Am. Chem. Soc., 1957, 79, 5441.
2. ^ Klaus Weissermel, Hans-Jürgen Arpe, Charlet R. Lindley, Stephen Hawkins (2003). "Chap. 7. Oxidation Products of Ethylene". Industrial Organic Chemistry. Wiley-VCH. pp. 159–161. ISBN 3527305785. 
3. ^ Lindsay Smith, J. R.; McKeer, L. C.; Taylor, J. M. (1993), "4-Chlorination of Electron-Rich Benzenoid Compounds: 2,4-Dichloromethoxybenzene", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV8P0167 ; Coll. Vol. 8: 167 
4. ^ Noyori, R.; Yokoyama, K.; Hayakawa, Y. (1988), "Cyclopentenones from α,α'-Dibromoketones and Enamines: 2,5-Dimethyl-3-Phenyl-2-Cyclopenten-1-one", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV6P0520 ; Coll. Vol. 6: 520 
5. ^ Raymond G. McGuire; Dimitrios A. Dimitroglou,"Evaluation of Shellac and Sucrose Ester Fruit Coating Formulations that Support Biological Control of Post-harvest Grapefruit Decay". Bio-control Science and Technology, Volume 9, Issue 1 March 1999 , pages 53 - 65