Sodium methyl allyl sulfonate, sodium methallyl sulfonate, and sodium methylallyl sulfonate are actually different names for the same chemical compound (molecular formula: C₄H₇NaO₃S, CAS No.: 1561-92-8). The differences lie only in naming conventions and terminology preferences. Below is a detailed analysis:
1. The Nature of Naming Differences
All three names refer to the same substance: sodium 2-methyl-2-propene-1-sulfonate (structural formula: CH₂=C(CH₃)CH₂SO₃Na). The variations arise from organic chemistry nomenclature rules and industry habits:
- Sodium methyl allyl sulfonate:
- A systematic name that clearly describes the methyl (methyl) and allyl (allyl) positions.
- “Allyl” specifically refers to the -CH₂-CH=CH₂ group, while “methyl allyl” indicates a methyl substitution at the α-position (i.e., CH₂=C(CH₃)-CH₂-).
- Sodium methallyl sulfonate:
- “Methallyl” is a contraction of “methyl allyl” (meth- + allyl) and is widely used in industrial contexts.
- The International Union of Pure and Applied Chemistry (IUPAC) accepts “methallyl” as a standard prefix for 2-methylallyl.
- Sodium methylallyl sulfonate:
- “Methylallyl” is simply a concatenated form of “methyl” and “allyl,” meaning the same as “methallyl.”
- Common in academic literature, emphasizing the direct linkage between the methyl and allyl groups.
2. Chemical Identity
Regardless of the name used, the core structure remains:
- Allylic double bond (CH₂=C(CH₃)-): Provides polymerization reactivity.
- Sulfonate group (-SO₃⁻Na⁺): Imparts water solubility and ionic character.
- Methyl substituent (-CH₃): Influences steric effects and reaction kinetics.
Verification Methods:
- All names share the same CAS number (1561-92-8).
- Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS) analyses yield identical results.
3. Usage Contexts for Different Names
Though they refer to the same compound, naming preferences vary by field:
| Name | Common Usage Context | Example |
|---|---|---|
| Sodium methallyl sulfonate | Industrial applications (polymers, water treatment) | Used in Dow Chemical product listings |
| Sodium methyl allyl sulfonate | Academic papers, patents | Frequently seen in ACS journal articles |
| Sodium methylallyl sulfonate | European chemical registrations (REACH) | ECHA registration documents use this format |
4. Distinction from Similar Compounds
Be aware that the following names refer to different chemicals:
- Sodium allyl sulfonate (CAS 2495-39-8):
- Structure: CH₂=CH-CH₂SO₃Na (no methyl group).
- More reactive but less thermally stable.
- Sodium styrene sulfonate (CAS 2695-37-6):
- Contains a phenyl ring (C₆H₅-CH=CHSO₃Na), making it more hydrophobic.
5. Practical Considerations
- Supplier labels: Different manufacturers may use different names, but the CAS number is the definitive identifier.
- Safety Data Sheets (SDS): Always verify the CAS number rather than relying solely on the name.
- Chemical reaction design: The naming difference does not affect reactivity, but it is important to distinguish it from non-methylated allyl sulfonates.
Conclusion
All three names refer to the same compound, with differences only in naming conventions. For industrial procurement or literature searches, always use the CAS number (1561-92-8) to ensure accuracy—especially in polymer formulations or regulatory compliance. For systematic naming, sodium 2-methyl-2-propene-1-sulfonate is the most precise IUPAC designation.
