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Heterocyclic building blocks

Methylthiouracil

Also known as 6-Methyl-2-thiouracil, Thimecil, Alkiron

CAS 56-04-2Formula C5H6N2OSMolar mass 142.18 g/molEC 200-252-3
GHS signal word: Warning. Pictograms: Harmful or irritant, Serious health hazard 89 suppliers listed
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Methylthiouracil chemical structure, C5H6N2OS, CAS 56-04-2
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
Crystals
Melting point
298.9 to 302.8
Solubility
VERY SLIGHTLY SOL IN COLD WATER, ETHER, ONE PART DISSOLVES IN ABOUT 150 PARTS BOILING WAโ€ฆ
HS code
293359
Category
Heterocyclic building blocks
UN number
UN 3077
Illustrative photo, assorted laboratory chemical bottles and jars on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is Methylthiouracil?

Plain description, key identifiers and synonyms

Methylthiouracil is a pyrimidone.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
6-methyl-2-sulfanylidene-1H-pyrimidin-4-one
CAS number
56-04-2 CAS number cross-checkedOther or deprecated CAS: 1123-10-0, 91795-77-6
EC number
200-252-3
Molecular formula
C5H6N2OS
UNII
QW24888U5F
MDL number
MFCD00006040
InChIKey
HWGBHCRJGXAGEU-UHFFFAOYSA-N
InChI
InChI=1S/C5H6N2OS/c1-3-2-4(8)7-5(9)6-3/h2H,1H3,(H2,6,7,8,9)
SMILES (canonical and isomeric)
CC1=CC(=O)NC(=S)N1

Synonyms

  • 6-Methyl-2-thiouracil
  • Thimecil
  • Alkiron
  • Methiocil
  • Basethyrin
  • Prostrumyl
  • Thiomecil
  • Thiothymin
  • Metacil
  • 2-Thio-6-methyluracil
  • Antibason
  • Methiacil
  • Methicil
  • Strumacil
  • Thyreonorm
  • Tiomeracil
  • Basecil
  • Muracil
  • Thyreostat I
  • Thiomidil
  • Tiotiron
  • Orcanon
  • Thioryl
  • Thiuryl
  • Thyril
Show all 39 synonyms
  • Tiorale M
  • 6-Methylthiouracil
  • 4-Methyl-2-thiouracil
  • 4(1H)-Pyrimidinone, 2,3-dihydro-6-methyl-2-thioxo-
  • 6-Thio-4-methyluracil
  • Metiltiouracilo
  • Usaf ek-6454
  • Methylthiouracile
  • 6-Methyl-2-mercaptouracil
  • Uracil, 6-methyl-2-thio-
  • Metiltiouracile
  • 2-Mercapto-6-methylpyrimid-4-one
  • 2-Mercapto-4-hydroxy-6-methylpyrimidine
  • Methylthiouracilum

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
Crystalsexp.
Odour
ODORLESSexp.
Taste
BITTERexp.
Melting point
298.9 to 302.8exp.
Solubility
VERY SLIGHTLY SOL IN COLD WATER, ETHER, ONE PART DISSOLVES IN ABOUT 150 PARTS BOILING WATER, SLIGHTLY SOL IN ALCOHOL, ACETONE, PRACTICALLY INSOL IN BENZENE, CHLOROFORM. FREELY SOL IN AQ SOLN OF AMMONIA & ALKALI HYDROXIDES.exp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
142.18 g/molcalc.
Exact mass
142.0201 Dacalc.
LogP (octanol/water)
0.74calc.
Topological polar surface area
48.65 ร…ยฒcalc.
Hydrogen bond donors
2calc.
Hydrogen bond acceptors
2calc.
Rotatable bonds
0calc.
Heavy atoms
9calc.
Rings
1calc.
Aromatic rings
1calc.
Fraction sp3 carbons
0.2calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Murcko scaffold

The ring system that remains when every side chain is removed

Murcko scaffold of this chemical, O=c1cc[nH]c(=S)[nH]1

O=c1cc[nH]c(=S)[nH]1

1 ring, 8 atoms, the Thiouracil ring system.

260 other chemicals share this scaffold

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Warning
GHS07: Harmful or irritant
Harmful or irritant
GHS08: Serious health hazard
Serious health hazard

Hazard statements

  • H302Harmful if swallowed.
  • H351Suspected of causing cancer.
Precautionary statements (9)
  • P203Obtain, read and follow all safety instructions before use.
  • P264Wash skin thoroughly after handling.
  • P270Do not eat, drink or smoke when using this product.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P317If swallowed: Get medical help.
  • P318If exposed or concerned, get medical advice.
  • P330Rinse mouth.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 3077

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Methylthiouracil suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 89 suppliers
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Where suppliers are based

89 suppliers in 15 countries

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Methylthiouracil price

Indicative price range per kg from live supplier offers

No published prices right now

Suppliers quote this chemical on request. Send one free request and compare quotes side by side.

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Uses and applications

What the substance is used for, by industry and function

Use classes: Pharmaceuticals.

Pharmacological actions

  • Antithyroid Agents

How it is made

Acetoacetic ester is condensed via hydration & de-ethanolation with thiourea.

Regulatory status

Inventories, regulations and trade controls that list this substance

United States

  • TSCA inventory (USA)
    Status: Active in US commerce, Regulatory flags: Significant new use rule

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Methylthiouracil is traded under.

HS 2933.59Indicative HS code

Compounds containing a pyrimidine ring (whether or not hydrogenated) or piperazine ring, other

World exports in 2024
$18.4B
+10.5% vs 2023, imports $24.8B
2019 to 2024
Top exporters
  1. Ireland43.6%
  2. Switzerland * partner reported26.3%
  3. China7.9%
Top importers
  1. Slovenia30.3%
  2. United States30.1%
  3. Germany15.3%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Methylthiouracil is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Methylthiouracil, based on the data on this page

What is Methylthiouracil?

Methylthiouracil is a pyrimidone.

What is the CAS number of Methylthiouracil?

The CAS registry number of Methylthiouracil is 56-04-2. Other or deprecated CAS numbers: 1123-10-0, 91795-77-6.

What is the molecular formula and weight of Methylthiouracil?

The molecular formula of Methylthiouracil is C5H6N2OS and its molar mass is 142.18 g/mol.

What is Methylthiouracil used for?

Use classes: Pharmaceuticals.

Is Methylthiouracil hazardous?

Methylthiouracil carries the GHS signal word "Warning". Main hazards: harmful if swallowed, suspected of causing cancer. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Methylthiouracil?

Methylthiouracil is usually classified under HS code 293359 (Compounds containing a pyrimidine ring (whether or not hydrogenated) or piperazine ringโ€ฆ). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Methylthiouracil?

CompoundList lists 89 suppliers of Methylthiouracil in China, United States, Germany, United Kingdom and 11 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

What is the price of Methylthiouracil?

Suppliers quote Methylthiouracil on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Methylthiouracil

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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