U.S. imports of Heterocyclic Compounds with Unfused Pyridine Ring (SITC 51574) totaled $135.7M in August 2026, imported from 35 countries.
Importers of Heterocyclic Compounds with Unfused Pyridine Ring paid $12.1M in duties in August 2026, an average duty rate of 12.18% — duty actually collected as a share of the imports that cleared customs, not the published tariff schedule. Heterocyclic Compounds with Unfused Pyridine Ring imports of $135.7M in August 2026 ran 17% above the year-to-date monthly average of $116.1M.
Last updated: August 2026 dataPyridine-ring heterocyclics — including pyridine itself and its hydrogenated analogs — are among the highest-volume nitrogen heterocyclics in international trade, serving as solvents, agrochemical building blocks, vitamin B3 (niacin) precursors, and pharmaceutical intermediates. The unfused ring criterion separates these compounds from quinoline and isoquinoline systems, which carry their own SITC subheading. India and China are major global producers of pyridine-based intermediates, and certain product lines have faced antidumping scrutiny in various markets.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
686 import shipments a month
Herbicides such as paraquat and diquat, as well as several insecticides and fungicides in the pyridyl class, are synthesized from pyridine intermediates. Pyridine derivatives are also used in the production of chlorpyrifos and related organophosphate compounds, making this subheading closely watched by agrochemical formulators.
No — the subheading explicitly covers pyridine-ring compounds 'hydrogenated or not,' so both fully aromatic pyridines and their partially or fully saturated analogs (such as piperidine) fall within this category, provided the ring remains unfused.
Basic heading 27 of 465 in section 5
Basic heading 51574 · $135.7M of $27.5B
Imports · August 2026
origin
China and United Kingdom together supply 71% of it. China pays 14.9% duty; India 4.3%.
customs district
Census does not publish district detail for this classification system.
destination
Census does not publish state detail for this classification system.
entry
Census does not publish port detail for this classification system.
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ImportsExports
Imports
$135.7MYoY · free account
Exports
$63.9MYoY · free account
12-mo low · imports
Low · free accountOver the twelve months to August 2026, the U.S. imported $1.3B of Heterocyclic Compounds with Unfused Pyridine Ring and exported $764.6M.
Through August 2026. Source: U.S. Census Bureau.