In general, if the atoms that make up the ring contain heteroatoms, such rings become heterocycles, and organic compounds containing heterocycles are called heterocyclic compounds. An article called Chemical control of reed canary grass on irrigation canals, published in 1968, which mentions a compound: 1970-40-7, Name is 2,3,5-Trichloropyridin-4-ol, Molecular C5H2Cl3NO, Product Details of 1970-40-7.
From 1962 to 1967, herbicides were evaluated for control of natural infestations of reed canary grass (Phalaris arundinacea) on canal banks of the Huntley, Montana, irrigation project. 2,2-Dichloropropionic acid (dalapon) and 3-amino-1,2,4-triazole ammonium thiocyanate (amitrole-T) controlled reed canary grass. These herbicides were compared with a number of others. Spring foliage treatments with a combination of amitrole-T at 2 lb./acre and dalapon or trichloroacetic acid (TCA) at 5 or 10 lb./acre were more effective than amitrole-T at 4 lb./acre. Amitrole-T was more tolerant to fine grasses such as Kentucky bluegrass (Poa pratensis) or redtop (Agrostis alba) than dalapon and in some situations it was more desirable than dalapon. Dalapon and TCA were more effective as late fall or early winter treatments to control reed canary grass during the following growing season. Rates of 20 or 40 lb./acre controlled the grass for one season even at the water’s edge where it is usually more persistent. At 5 to 10 lb./acre, 2,3,5-trichloro-4-pyridinol (pyriclor) controlled reed canary grass, and it also was effective at 2 lb./acre with 2 lb./acre of amitrole-T.
Different reactions of this compound(2,3,5-Trichloropyridin-4-ol)Product Details of 1970-40-7 require different conditions, so the reaction conditions are very important.
Reference:
Isoquinoline – Wikipedia,
Isoquinoline | C9H7N – PubChem