Diphenic Acid
Diphenic acid (2,2'-biphenyldicarboxylic acid) is used in polymer synthesis and as a chiral resolving agent. Although biphenyl-based, classified under HTS 2917.39.70.00 as aromatic polycarboxylic acid per Chapter 29 structure. Provides rigid linker in specialty polymers.
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Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If single ortho-carboxylic acid substitution
Monocarboxylic aromatic acids classified earlier in numerical order.
If racemic technical mixtures
Mixtures of isomers fall outside Chapter Note 1(b) if not same compound.
If pre-polymerized forms
Degree of polymerization determines Chapter 29 vs Chapter 39.
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Import Tips & Compliance
• Biphenyl structure confirmed aromatic per Chapter 29; not Chapter 27 hydrocarbon
• Chiral purity documentation required for resolution agent applications
• Distinguish from Chapter 38 optical resolving preparations by purity >98%
Related Products under HTS 2917.39.70.00
Isophthalic Acid Technical Grade
Isophthalic acid is a meta-substituted aromatic dicarboxylic acid used in alkyd resins, polyester coatings, and copolyesters. Classified under HTS 2917.39.70.00 as an aromatic polycarboxylic acid not specifically enumerated elsewhere in heading 2917. This meta-isomer provides superior chemical resistance in coatings.
1,2,4,5-Tetracarboxybenzene (Pyromellitic Acid)
Pyromellitic acid, the diacid precursor to PMDA, is used in specialty polyimides and electronic materials. Classified under HTS 2917.39.70.00 as an aromatic polycarboxylic acid (four -COOH groups on benzene). Typically handled as dihydrate form.
Benzene-1,2,3-tricarboxylic Acid (Hemicellic Acid)
Hemicellic acid is a tri-carboxylic aromatic acid used in resin synthesis and as a pharmaceutical intermediate. It falls under HTS 2917.39.70.00 as an aromatic polycarboxylic acid not otherwise specified. The 1,2,3-substitution pattern gives unique reactivity.
Mellophanic Acid
Mellophanic acid (benzene-1,2,3,5-tetracarboxylic acid) serves as a monomer for heat-resistant polymers and electronic materials. Classified HTS 2917.39.70.00 as aromatic polycarboxylic acid with unsymmetrical substitution. Enables cross-linked network structures.
Prehnitic Acid
Prehnitic acid (benzene-1,2,4,5-tetracarboxylic acid) used in polyimide films and high-performance composites. Identical reactivity to pyromellitic acid but different substitution pattern. HTS 2917.39.70.00 as aromatic polycarboxylic acid, other.
Benzene-1,3,5-tricarboxylic Acid (Trimesic Acid)
Trimesic acid features symmetrical 1,3,5-tri carboxylic substitution on benzene, ideal for metal-organic frameworks (MOFs) and coordination polymers. HTS 2917.39.70.00 aromatic polycarboxylic acid. Perfect 120° linker geometry.