Morpholine is an organic chemical compound having the chemical formula O(CH2CH2)2NH. This heterocycle features both amine and ether functional groups. Because of the amine, morpholine is a base; its conjugate acid is called morpholinium. For example, treating morpholine with hydrochloric acid makes the salt morpholinium chloride. The naming of morpholine is attributed to Ludwig Knorr, who incorrectly believed it to be part of the structure of morphine.
|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||87.122 g·mol−1|
|Odor||Weak ammonia-like or fish-like|
|Melting point||−5 °C (23 °F; 268 K)|
|Boiling point||129 °C (264 °F; 402 K)|
|Vapor pressure||6 mmHg (20 °C)|
|Acidity (pKa)||8.36 (of conjugate acid)|
|Main hazards||Flammable, Corrosive|
|Safety data sheet||hazard.com|
|R-phrases (outdated)||R10 R20/21/22 R34|
|S-phrases (outdated)||(S1/2) S23 S36 S45|
|Flash point||31 °C (88 °F; 304 K)|
|275 °C (527 °F; 548 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|1220 mg/kg (mammal, oral)|
525 mg/kg (mouse, oral)
1050 mg/kg (rat, oral)
LC50 (median concentration)
|365 ppm (mouse, 2 hr)|
|US health exposure limits (NIOSH):|
|TWA 20 ppm (70 mg/m3) [skin]|
|TWA 20 ppm (70 mg/m3) ST 30 ppm (105 mg/m3) [skin]|
IDLH (Immediate danger)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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.
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).
Morpholine is widely used in organic synthesis. For example, it is a building block in the preparation of the antibiotic linezolid, the anticancer agent gefitinib (Iressa) and the analgesic dextromoramide.
As a fruit coatingEdit
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. The European Union has forbidden the use of morpholine in fruit coating.
As a component in fungicidesEdit
Morpholine derivatives used as agricultural fungicides in cereals are known as ergosterol biosynthesis inhibitors.
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- McGuire, Raymond G.; Dimitroglou, Dimitrios A. (1999). "Evaluation of Shellac and Sucrose Ester Fruit Coating Formulations that Support Biological Control of Post-harvest Grapefruit Decay". Bio-control Science and Technology. 9 (1): 53–65.
- "Morpholine". Scientific Analysis Laboratories Ltd. Archived from the original on 2012-04-26.
- "Morpholine Issues in the United Kingdom". Northwest Horticultural Council. September 28, 2010. Archived from the original on April 26, 2012.
- Media related to Morpholines at Wikimedia Commons