Morpholine CAS 110-91-8

What is Morpholine?

Morpholine is a saturated six-membered ring containing both a nitrogen and an oxygen, sitting opposite each other — C₄H₉NO. It is simultaneously a secondary amine and an ether, and both halves of that description matter commercially.

The ring oxygen is the key to its behaviour. Being electron-withdrawing, it pulls density away from the nitrogen and makes morpholine a markedly weaker base than piperidine — a conjugate acid pK_a near 8.4 against around 11. That is roughly a thousandfold difference, and it is exactly why morpholine works as a mild neutralising amine where a stronger base would overshoot.

It is a clear, colourless liquid boiling at about 129 °C with a density close to that of water, a flash point near 31 °C and complete miscibility with water. It also dissolves a remarkable range of organic materials — dyes, resins, waxes, shellac, casein — which gives it a secondary life as a specialty solvent.

Commercially, morpholine has three substantial markets. It is one of the standard volatile neutralising amines for boiler and steam condensate systems. It supplies the morpholino group to a family of delayed-action rubber accelerators. And it is the raw material for optical brighteners, morpholine-class cereal fungicides and a long list of fine chemical intermediates — including N-methylmorpholine.

Why morpholine specifically

• Mild basicity by design. The ring oxygen makes it about a thousand times less basic than piperidine, which is what allows precise pH control in condensate systems without overshooting.
• A low steam distribution ratio. It partitions toward the water phase more than cyclohexylamine does, so it protects the parts of a condensate system closest to the boiler — the complement to a high-ratio amine, not a competitor.
• Unusual solvent power. Dissolves dyes, resins, waxes, shellac and casein, which few amines of this size manage, giving it a genuine second market as a specialty solvent.
• A versatile building block. The morpholino group appears across rubber accelerators, optical brighteners, cereal fungicides and pharmaceutical actives.

How Morpholine is Manufactured

Morpholine is made by dehydrating and cyclising a two-carbon feedstock with ammonia. Two routes dominate, and they leave different impurity signatures.

• Diethylene glycol amination. The modern route reacts diethylene glycol with ammonia and hydrogen over a supported metal catalyst at elevated temperature and pressure. Water is eliminated and the ring closes, giving morpholine with aminoethoxyethanol and related species as by-products.
• Diethanolamine dehydration. The older route dehydrates diethanolamine with concentrated sulphuric acid, closing the ring directly. It is simpler but produces an acid waste stream and tends to leave higher residual sulphate.
• Separation. The crude product is resolved by fractional distillation with ammonia and water recovery. Morpholine forms an azeotrope with water, so drying to a low-water specification is a distinct operation rather than a by-product of fractionation.
• Finishing. The product is taken to specification and filled into drums, IBCs or tanks, with nitrogen blanketing where colour matters. Low-colour grades receive additional treatment.

Typical Commercial Specification

Figures below are representative of standard commercial grade. Boiler-treatment and low-colour grades with tighter limits are available — send us the specification you work to and we will quote against it.

Physical & Chemical Properties

Reactivity in practice

A secondary amine and an ether in one ring. Four reaction types cover nearly all of its commercial chemistry:

• Sulfenamide and thio chemistry. Reaction with benzothiazole sulfenyl chemistry gives delayed-action accelerators, and oxidative coupling gives morpholine disulphide — both long-standing rubber chemicals.
• Neutralisation. As a mild volatile base it neutralises carbonic acid in steam condensate, raising pH enough to control corrosion without the overshoot a strong base would cause.
• N-alkylation and N-acylation. Methylation gives N-methylmorpholine; acylation and arylation install the morpholino group found in optical brighteners, fungicides and pharmaceutical actives.
• Solvent action. Used neat or in blends to dissolve waxes, resins, shellac and dyes — a physical rather than chemical application, but a commercially significant one.

Morpholine vs Piperidine, Piperazine and N-Methylmorpholine

The saturated six-membered nitrogen heterocycles are easy to confuse and behave quite differently. What separates them is what else is in the ring: a second nitrogen makes the molecule difunctional and solid, an oxygen pulls electron density away and weakens the base, and methylating the nitrogen removes the N-H altogether.

Stated plainly: piperidine is the strongest base of the four and the most nucleophilic; piperazine is the only difunctional one and the only solid; morpholine's ring oxygen makes it roughly a thousand times less basic than piperidine, which is exactly why it works as a mild neutralising amine; and N-methylmorpholine, having no N-H at all, acts as a catalyst and base rather than a building block — and cannot form a nitrosamine, which matters increasingly in rubber and personal care. They substitute for one another only rarely.

Industries We Supply Morpholine To

The same molecule leaves our warehouse for very different factories. What changes between them is not the CAS number but the grade — sulphate, colour or organic by-products — and the documentation each sector expects.

Where Morpholine is Used

Morpholine spans water treatment, rubber chemistry and fine chemicals. These are the end uses our customers buy it for, roughly in order of volume.

In boiler and condensate treatment

Carbon dioxide carried over with steam dissolves in condensate to form carbonic acid, which attacks return lines from inside. Morpholine is one of the two standard neutralising amines for this duty. Its distinguishing property is a relatively low distribution ratio — it partitions toward the water phase rather than staying with the vapour — so it concentrates in the early condensate near the boiler. Cyclohexylamine does the opposite and carries further down the system. Treatment packages blend the two precisely because neither covers the whole circuit alone. Where steam contacts food, feed or pharmaceutical product, the treatment chemical must be approved for that service at destination.

In rubber chemicals

The morpholino group appears in delayed-action benzothiazole sulfenamide accelerators and in morpholine disulphide, a sulphur donor used in efficient-vulcanisation systems. These have a long history in tyre and technical rubber compounding. Compounders should be aware that morpholine-based accelerators have been reformulated or substituted in some markets over nitrosamine concerns, since a secondary amine released during cure can be nitrosated — the position differs by market and by application, and it is worth confirming rather than assuming.

In optical brighteners and dyes

Fluorescent whitening agents used in detergents, paper and textiles are built on stilbene and related cores, and morpholine appears both as a substituent and as a process solvent in their manufacture. This is a market where colour on the incoming amine is a real specification: the whole point of the finished product is whiteness, and any tint carried in from a raw material is visible in the end use.

As a specialty solvent

Morpholine dissolves an unusually wide range of materials for a molecule of its size — waxes, resins, shellac, casein and many dyes. That makes it useful in polishes, coating formulations and processing aids, often as a co-solvent or as a solubilising base that forms a soap with a fatty acid. It is a physical application rather than a chemical one, but a commercially significant share of volume goes this way.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis. The methods behind the numbers are standard across the industry, and we are happy to share them or to work to your own in-house test protocol.

• Assay and by-product profile — gas chromatography, which quantifies residual diethylene glycol, aminoethoxyethanol and related oxygenates alongside the main component.
• Water content — Karl Fischer titration. Morpholine forms an azeotrope with water, so low-water grades require a dedicated drying step and should be verified rather than assumed.
• Colour — APHA / Hazen against a standard. Critical for optical brightener and dye service, where any tint carries into a product sold on whiteness.
• Sulphate and chloride — ion chromatography. Both matter directly in boiler treatment, where corrosive anions are being introduced into a steam system.
• Specific gravity — a quick practical check. Morpholine's density is close to 1.00, and a drift usually indicates water or glycol carry-over.
• Distillation range — a fast check for by-product and moisture carry-over before any instrument confirms it.

Common Process Problems & Likely Causes

When morpholine misbehaves in a plant, the cause is usually one of a short list of things. This table is the shortcut our technical desk works through before anyone opens a complaint file.

Packaging, Storage & Shipping

• Standard packing. 200 kg net in lined steel or HDPE drums, with 1000 L IBCs for larger users.
• Bulk packing. Road tankers and ISO tank containers for water treatment formulators and continuous plants.
• Inert blanketing. Nitrogen-blanketed at fill where colour or low water content matters.
• Storage. Cool, dry, well-ventilated and bunded area away from heat, ignition sources, oxidisers and acids, with containers kept tightly closed.
• Materials of construction. Stainless steel, carbon steel or suitable lined vessels. Avoid copper, brass, bronze, aluminium and mercury, all of which are attacked by amines.
• Shelf life. Typically 12 months in unopened original packing under those conditions. Beyond that, re-test rather than assume.
• Nitrite segregation. As a secondary amine, morpholine should be stored and handled well away from nitrites and other nitrosating agents. This is a segregation rule rather than a precaution — treat it as one.
• Transport classification. UN 2054, Morpholine, Class 8 corrosive with subsidiary risk 3 flammable, Packing Group I — the most stringent packing group, which requires more robust packaging and restricts some transport options.
• Container loading. Palletised and secured for FCL; LCL consolidation and tank arrangements available by volume.

Hazards & Safe Handling

Morpholine is corrosive and flammable, ships at the most stringent packing group, and is a secondary amine with an associated nitrosamine consideration. It must be handled by trained personnel under a proper risk assessment. The classifications below are indicative — the current SDS supplied with your consignment is the governing document.

• Nitrosamine consideration. Morpholine is a secondary amine and can be nitrosated to N-nitrosomorpholine in the presence of nitrosating agents. This is a well-documented concern and it shapes how the product is handled, stored and formulated. Keep nitrites and nitrogen oxides out of the handling area and design formulations so the two cannot meet.
• Exposure control. Handle in a closed system or under local exhaust ventilation. Both vapour and skin contact are meaningful exposure routes.
• PPE. Chemical-resistant gloves, chemical goggles and face shield, chemical-resistant clothing, and respiratory protection suited to the task.
• Ignition control. The flash point is near 31 °C, so a warm process area or heated transfer line can put the headspace into the flammable range. Keep away from heat and ignition sources and classify the zone accordingly.
• Incompatibilities. Strong oxidising agents, strong acids, acid chlorides, nitrites and nitrogen oxides, and copper, brass, bronze and aluminium equipment.
• Spill response. Eliminate ignition sources and ventilate. Contain, absorb with inert non-combustible material and collect in a labelled closed container. Do not wash to drain.
• Fire. Use alcohol-resistant foam, dry chemical or carbon dioxide; cool exposed containers with water spray. Decomposition releases nitrogen oxides — use self-contained breathing apparatus.
• First aid. Remove contaminated clothing immediately, wash skin with plenty of water, flush eyes for at least 15 minutes, move to fresh air, and seek medical attention with the SDS to hand.

Regulatory & Compliance Notes

Morpholine is a long-established industrial chemical listed on the major national inventories, but it carries two regulatory dimensions beyond ordinary chemical control: the nitrosamine question that follows every secondary amine, and food-contact restrictions in some territories. The notes below are orientation rather than legal advice — confirm your own position with your regulatory adviser before importing.

• Inventory status. Listed on the principal chemical inventories in the major importing regions. Ask us for the inventory confirmation relevant to your destination country.
• Import registration. Several territories require the importer to hold a registration or notification before a consignment lands. Start that process early — it is the most common cause of delay at destination.
• Hazard communication. Supplied with an SDS compliant with the format applicable to your region, and labelled in line with the GHS classification for the product.
• Nitrosamine controls. Because morpholine can be nitrosated to N-nitrosomorpholine, several sectors — rubber compounding and personal care in particular — apply limits on nitrosatable amines or on nitrosamine content in finished goods. Where your product falls under such a scheme, build the assessment in at the design stage.
• Food contact and fruit coatings. Morpholine fatty acid salts have historically been used in fruit coating waxes. Permission for this use differs substantially by territory and has been withdrawn or restricted in several markets. Confirm the current position at destination before any food-contact use.
• Steam that contacts food or feed. Where morpholine treats boiler water producing steam that contacts food, feed or pharmaceutical product, the treatment chemical must be approved for that service at destination, with permitted lists and concentration limits differing by territory.
• Dangerous goods. UN 2054, Morpholine, Class 8 corrosive with subsidiary risk 3, Packing Group I. The stringent packing group restricts some transport options — plan the routing early.

We Supply Morpholine Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Morpholine from India to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation, dangerous-goods paperwork and freight so the material arrives ready to use.

• Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
• Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other Indian ports arranged where it suits the routing.
• Documentation. Commercial invoice, packing list, certificate of origin, COA, SDS and dangerous-goods declaration issued as a complete set.
• Flexible volumes. A single drum for laboratory qualification, through LCL consolidations, up to repeat full loads on a supply contract.
• Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.

Buying Morpholine from Chelora

We are an independent sourcing and supply partner. For morpholine that means matching the grade to the market — low sulphate and chloride for boiler treatment, low colour for brighteners and dyes, controlled organic by-products for fine chemical work — rather than selling whatever happens to be in the tank.

• Documentation on every lot. Batch-specific COA, current SDS and TDS issued with the consignment, not weeks afterward.
• Samples before commitment. Trial quantities for process qualification ahead of a commercial order.
• Quantities. From a single 200 kg drum through to tank loads and ongoing contract supply.
• Export experience. Packing Group I dangerous-goods documentation, packing and labelling for sea and road freight.
• Technical support. Direct access to people who know the chemistry, for questions on distribution ratio, anion limits or nitrosamine risk.
• Related intermediates. N-methylmorpholine, cyclohexylamine, diethylethanolamine, piperazine and the wider amine range from one supplier.

How ordering works

• Send the enquiry. Product, grade or specification, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
• We quote. Price, lead time, packing and a sample COA, normally within one working day.
• Sample and qualify. For first orders or critical applications, we send a trial quantity so your lab can sign off before you commit.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Production and QC. Material allocated and released against a batch-specific COA, with a pre-shipment sample where the application calls for it.
• Ship and document. Packed, labelled and loaded with the full export and dangerous-goods document set, and tracked through to arrival.

Related Heterocyclic & Treatment Amines

Buyers of morpholine usually source several of these alongside it. Consolidating them on one order cuts freight cost and gives you a single point of contact for documentation.