Morpholine

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, when morpholine is neutralized by hydrochloric acid, one obtains the salt morpholinium chloride.

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Uses

Industrial applications

Morpholine is a common additive, in ppm 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 even 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).^[1]

It is commonly used to generate enamines.^[2]

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®).

Morpholine is used as a chemical emulsifier in the process of waxing fruit. Fruits make waxes naturally to protect against insects and fungal contamination, but this can be lost by means of the food processing companies when they clean the fruit. As a result, an extremely small amount of new wax is applied and morpholine is then added and used as an emulsifier to evenly coat a fruit with the wax.

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

As a component in fungicides

Morpholine derivatives used as agricultural fungicides in cereals are known as Ergosterol Biosynthesis Inhibitors.

• Morpholines
  • fenpropimorph
  • tridemorph

• Piperidines
  • fenpropidin

References

1. ^ Lindsay Smith, J. R.; McKeer, L. C.; Taylor, J. M. (1993). "4-Chlorination of Electron-Rich Benzenoid Compounds: 2,4-Dichloromethoxybenzene". Org. Synth.; Coll. Vol. 8: 167. 
2. ^ 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.; Coll. Vol. 6: 520. 

• National Institute for Occupational Safety and Health (2000). MORPHOLINE. International Chemical Safety Cards. Retrieved on 5 November 2005.