isophthalic acid

Very low
UK/ˌaɪ.səʊˈθæl.ɪk ˈæs.ɪd/US/ˌaɪ.soʊˈθæl.ɪk ˈæs.ɪd/

Technical/Scientific

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Definition

Meaning

An aromatic dicarboxylic acid used primarily in the production of polyesters, resins, and plasticizers.

A specific isomer of benzene-1,3-dicarboxylic acid, important as a monomer in the chemical industry for creating high-performance polymers with specific thermal and mechanical properties.

Linguistics

Semantic Notes

The term is specific to organic chemistry and polymer science. It denotes not just an acid, but a specific structural isomer (meta-substituted) of phthalic acid, which dictates its reactivity and application.

Dialectal Variation

British vs American Usage

Differences

No significant lexical differences. Spelling of related terms (e.g., 'polymerisation' vs 'polymerization') may follow regional conventions.

Connotations

Purely technical with identical denotation in both varieties.

Frequency

Equally rare outside professional chemistry contexts in both regions.

Vocabulary

Collocations

strong
polyester resinpolymer productionchemical intermediate
medium
production ofbased onderived from
weak
purecommercialgrade

Grammar

Valency Patterns

Isophthalic acid is used in XX containing isophthalic acidX based on isophthalic acid

Vocabulary

Synonyms

Strong

IPA (abbreviation in industry)

Neutral

benzene-1,3-dicarboxylic acidm-phthalic acid

Weak

meta-isomer

Vocabulary

Antonyms

terephthalic acid (para-isomer)phthalic acid (ortho-isomer, though technically not a direct antonym)

Phrases

Idioms & Phrases

  • None

Usage

Context Usage

Business

Used in procurement, production reports, and specifications in the chemical and plastics industries.

Academic

Central in research papers on polymer chemistry, material science, and organic synthesis.

Everyday

Virtually never used.

Technical

Precise term in chemical formulas, safety data sheets, process descriptions, and patent applications.

Examples

By Part of Speech

verb

British English

  • The compound isophthalated rapidly under heat.
  • We need to isophthalate the precursor.

American English

  • The compound isophthalated quickly under heat.
  • We need to isophthalate the precursor.

adverb

British English

  • The reaction proceeded isophthalically.
  • The polymer was modified isophthalically to enhance properties.

American English

  • The reaction proceeded isophthalically.
  • The polymer was modified isophthalically to improve properties.

adjective

British English

  • The isophthalic-based resin cured well.
  • An isophthalic polyester coating was applied.

American English

  • The isophthalic-based resin cured well.
  • An isophthalic polyester coating was applied.

Examples

By CEFR Level

A2
  • (Not applicable for this technical term at A2 level.)
B1
  • Isophthalic acid is a chemical used in making plastics.
B2
  • The production of certain durable plastics relies on isophthalic acid as a key ingredient.
C1
  • The researchers substituted terephthalic acid with isophthalic acid in the copolymer to alter its crystallinity and thermal resistance.

Learning

Memory Aids

Mnemonic

ISO means 'equal' but here denotes isomer; THALIC comes from 'naphthalene'. Think: 'I So need the THALIC acid with groups opposite (meta) each other.'

Conceptual Metaphor

A BUILDING BLOCK or MONOMER (a fundamental unit for constructing larger polymer chains).

Watch out

Common Pitfalls

Translation Traps (for Russian speakers)

  • Direct translation 'изофталевая кислота' is correct. Avoid confusing with 'фталевая кислота' (phthalic acid) or 'терефталевая кислота' (terephthalic acid), which are different isomers.

Common Mistakes

  • Misspelling as 'isopthalic' (missing 'h')
  • Confusing it with its isomers (phthalic, terephthalic acid).
  • Incorrect stress on the first syllable ('ISO-phthalic').

Practice

Quiz

Fill in the gap
In the production of high-performance unsaturated polyester resins, acid is often used alongside maleic anhydride.
Multiple Choice

Isophthalic acid is primarily classified as what type of compound?

FAQ

Frequently Asked Questions

Its primary use is as a monomer in the synthesis of unsaturated polyester resins (UPR), which are used in fiberglass-reinforced plastics, coatings, and molding compounds.

They are isomers. The two carboxylic acid groups in isophthalic acid are in the meta position (1,3) on the benzene ring, while in terephthalic acid they are in the para position (1,4). This structural difference leads to different polymer properties.

Like many industrial chemicals, it can be an irritant to skin, eyes, and the respiratory system. Safe handling requires consulting its Material Safety Data Sheet (MSDS/SDS) and using appropriate personal protective equipment.

Not directly. Consumers encounter the finished polymers derived from it, such as parts of boats, car bodies, or durable coatings, but not the pure acid itself.