Methylurea
[CAS 598-50-5]

Identification

• Classification: Chemical reagent >> Organic reagent >> Urea
• Name: Methylurea
• Synonyms: Monomethyl urea; N-Methylurea
• Molecular Formula: C₂H₆N₂O
• Molecular Weight: 74.08
• CAS Registry Number: 598-50-5
• EC Number: 209-935-0
• SMILES: CNC(=O)N

Properties

• Density: 1.2±0.1 g/cm³ Calc.^*
• Melting point: 96 - 101 °C (Expl.)
• Boiling point: 110.6±23.0 °C 760 mmHg (Calc.)^*
• Flash point: 20.7±22.6 °C (Calc.)^*
• Solubility: water: 1000 g/L (20 °C) (Expl.)
• Index of refraction: 1.475 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H319
• Safety Statements: P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302

chemBlink Chemical Story

Methylurea, CAS 598-50-5, is a simple substituted urea used as an intermediate in organic, pharmaceutical, and fine-chemical synthesis. It is also known as N-methylurea, 1-methylurea, or monomethylurea. Its molecular formula is C₂H₆N₂O and its molecular weight is 74.08. Structurally, it can be written as CH₃NHCONH₂: one of the hydrogen atoms on a urea nitrogen has been replaced by a methyl group. :contentReference[oaicite:2]{index=2}

Urea itself is one of the simplest and most familiar nitrogen-containing organic compounds. Its structure, NH₂CONH₂, contains a carbonyl group flanked by two nitrogen atoms. Resonance between the nitrogens and the carbonyl gives the molecule properties that are quite different from those of ordinary amines.

Methylurea changes this highly symmetric structure in the smallest possible way: one nitrogen receives a CH₃ group.

That small substitution breaks the symmetry of urea. The two nitrogen atoms are no longer equivalent. One remains NH₂, while the other becomes NHCH₃. As a result, reactions involving the two nitrogens can become chemically distinguishable.

This makes methylurea useful as a starting material when a chemist wants to introduce a single N-methyl group into a larger urea-derived structure. Instead of constructing an unsymmetrical urea from scratch at a later stage, the methyl substituent is already present at the beginning.

The urea carbonyl also remains chemically important. Urea derivatives can participate in condensation reactions with carbonyl compounds, activated electrophiles, and bifunctional reagents. Through these transformations, a small open-chain molecule can become part of a much larger heterocyclic or polycyclic structure.

One documented application is the synthesis of methyl-substituted glycoluril derivatives. Glycolurils are bicyclic compounds containing multiple urea-derived nitrogen and carbonyl groups. They are formed through condensation chemistry in which urea-type molecules and carbonyl compounds create new carbon-nitrogen bonds and eventually close into compact ring systems. Commercial reference literature specifically records N-methylurea as a reagent for the synthesis of bis(aryl)(hydroxyalkyl)(methyl)glycoluril derivatives. :contentReference[oaicite:3]{index=3}

This transformation illustrates an important idea in heterocyclic synthesis. A molecule with only two carbon atoms can already contain several atoms destined for the final ring system. The carbonyl carbon and two nitrogens of the urea unit provide a preorganized C-N-C-N framework that can be incorporated into more complex structures through condensation.

Methyl substitution adds another layer of control. If ordinary urea were used, the two nitrogen atoms would initially be identical. In methylurea, one nitrogen is already differentiated by the CH₃ group. This asymmetry can influence which nitrogen remains substituted in the final product and can help create molecular structures that would otherwise require additional steps.

The compound is also useful more broadly as a source of the N-methylurea motif. Urea groups are common in medicinal chemistry because the carbonyl oxygen and nitrogen atoms can participate in hydrogen bonding. Substituents on the nitrogen atoms can tune size, polarity, conformation, and molecular recognition.

This does not mean methylurea itself has the pharmacological activity of urea-containing drugs. Its principal role is as a small synthetic precursor from which more elaborate molecules can be constructed.

Methylurea can also be produced on industrial scale. Commercial chemical references describe manufacture by introducing monomethylamine into molten urea. This route reflects the close structural relationship between the two compounds: methylurea is literally a monomethyl-substituted urea. :contentReference[oaicite:4]{index=4}

Under ordinary conditions, methylurea is a crystalline solid. Commercial suppliers list it as white or off-white crystals, with a melting point around 93 °C and very high water solubility. Sigma-Aldrich and Fisher Scientific both supply it as a laboratory reagent. :contentReference[oaicite:5]{index=5}

There is also an unexpected environmental chemistry connection.

Analytical studies of caffeine degradation have reported N-methylurea among compounds associated with transformation of caffeine in environmental systems. Caffeine contains several methylated nitrogen atoms embedded in a much more complex purine-like ring structure. During degradation, successive bond cleavage and demethylation can produce much smaller nitrogen-containing fragments. Commercial reference literature therefore notes methylurea as a potential byproduct associated with caffeine degradation. :contentReference[oaicite:6]{index=6}

This connection is chemically interesting because the structures look completely unrelated at first sight. Caffeine is a fused heterocyclic molecule containing several carbonyls and methylated nitrogens, while methylurea is only CH₃NHCONH₂. But degradation chemistry can dismantle a complicated molecule until only small fragments of its original nitrogen-carbonyl architecture remain.

Methylurea therefore has two very different chemical identities depending on the direction in which one looks.

In synthetic chemistry, it is a small starting material from which complexity can grow.

In degradation chemistry, it can represent the opposite process: a small fragment that appears after a more complicated molecule has been broken down.

That contrast makes methylurea more interesting than its tiny formula suggests.

Only two carbon atoms are present, yet the molecule already contains a carbonyl, two nitrogens, a built-in methyl substituent, and the ability to participate in condensation chemistry. It can serve as a precursor to larger heterocyclic structures, while also appearing as a recognizable fragment in the chemical dismantling of more complex nitrogen compounds.

Methylurea is therefore a useful reminder that molecular importance is not proportional to molecular size. Sometimes a very small molecule matters precisely because it contains a compact arrangement of atoms that can either be assembled into something much larger or recognized as the residue of something that has been taken apart.

References

1. NIST Chemistry WebBook. Urea, methyl-, CAS 598-50-5. Molecular formula C₂H₆N₂O; molecular weight 74.0818.

2. PubChem. Methylurea, CID 11719. CAS 598-50-5.

3. Sigma-Aldrich. N-Methylurea, CAS 598-50-5. Linear formula CH₃NHCONH₂.

4. Antonova, M. M. et al. (2014). Synthetic studies involving methyl-substituted glycoluril derivatives. Chemistry of Heterocyclic Compounds, 50, 503.

5. Zarrelli, A. et al. (2014). Environmental transformation studies involving caffeine-related degradation products. Science of the Total Environment, 470-471, 453.

6. Commercial chemical references describing industrial production of methylurea from monomethylamine and urea.