4-Methylthiazole (CAS 693-95-8) — Top Note Fragrance Ingredient

ByThe Good Scents



gourmand

4-Methylthiazole

CAS 693-95-8

Note
top
Volatility
high
MW
99.15
Data as of: Jun 2026

What Is 4-Methylthiazole?

4-Methylthiazole (CAS 693-95-8) is an aroma chemical used as a fragrance and flavour ingredient. Its odour is described as sweet, fish and garlic, placing it within the gourmand family as a top note with high volatility. With a molecular weight of 99.15 (formula C4H5NS), it is handled by perfumers as a building block for compositions where a sweet character is desired. The data below is compiled from public chemical and regulatory sources.

Safety Profile

HANDLE WITH CARE

Generally safeUse with awarenessProfessional use
CAS
693-95-8
Formula
C4H5NS
MW
99.15
InChIKey
QMHIMXFNBOYPND-UHFFFAOYSA-N
4-Methylthiazole 2D structure

4-Methylthiazole
C4H5NS
Layer 1 · Enthusiast

What Does 4-Methylthiazole Smell Like?

The odour profile of 4-Methylthiazole is reported as sweet, fish, garlic, spices, cold, sour, burnt, acid, warm, musky, sweaty, ammonia/urinous, decayed, wood, grass, flower, chemical, edible. The dominant facet is its sweet character, with the remaining notes adding nuance and complexity. As a top note it contributes to the opening of a fragrance. Perceived intensity and exact character depend on concentration, the carrier and the surrounding accord.

Scent Profile

Profile derived from public odour-descriptor data; relative, not absolute.

Layer 2

Chemistry & Properties

The Chemistry

4-Methylthiazole has the molecular formula C4H5NS and a molecular weight of 99.15 g/mol. Its canonical SMILES representation is CC1=CSC=N1. Its reported log P (XLogP) of 0.97 indicates a moderately polar molecule, which informs how it partitions in a formula. Physical constants below are drawn from PubChem and EPA CompTox public datasets.

Physical & Chemical Properties

Molecular Weight 99.15 g/mol
Boiling Point 134.3 °C
Melting Point -13.75 °C
Flash Point 35.38 °C
Density 1.09 g/cm³
Vapor Pressure 10.03 mmHg
Water Solubility 0.083 g/L
XLogP 0.97

Perfumer Guide

Note Position
Top
Volatility
High
Primary Odour
Sweet

Alternatives & Comparisons

Ingredients occupying a similar odour space — useful as substitutes or companions when 4-Methylthiazole is unavailable or restricted.

1
Isopentylamine CAS 107-85-7

Shares bakery, sweet, fish character — a candidate substitute or companion in the same odour space.

2
2-Acetyl-3-Ethylpyrazine CAS 32974-92-8

Shares bakery, sweet, fish character — a candidate substitute or companion in the same odour space.

3
Ethyl 3-(Furfurylthio) Propionate CAS 94278-27-0

Shares bakery, sweet, fish character — a candidate substitute or companion in the same odour space.

Layer 3

Safety & Regulatory

⚠ Regulatory Disclaimer

General reference only. IFRA, REACH and EU Cosmetics Regulation standards update periodically. Consult the current IFRA Standards Library before formulating. Not legal or regulatory advice.

IFRA Status

No IFRA restriction recorded in the data set. This is not a guarantee of unrestricted status — always confirm against the current IFRA Standards Library.

GHS Classification

Signal word: Warning

H302
Formulating with 4-Methylthiazole?

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References & Sources

  1. PubChem Compound Summary (NIH) — search by InChIKey
  2. EPA CompTox Chemicals Dashboard — physicochemical & fate data
  3. IFRA Standards Library (49th / 51st Amendment)
Sources: PubChem (NIH) · EPA CompTox · IFRA Standards Library · public GHS classification. Odour descriptors are original editorial summaries of public profiles, not reproduced from any single proprietary source.

Data: PubChem (NIH), EPA CompTox, IFRA. Last reviewed: Jun 2026.

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