We can “bin‐classify” these fifteen aryl halides by looking directly at a few quantitative descriptors that one would normally pull from a property database. For example, note that (a) the “topological polar surface area” (tpsa) differs markedly between those that contain a nitrogen heterocycle (tpsa ≈ 12.9 Å² for all the pyridines) and those based solely on a benzene ring (with tpsa = 0 for the simple benzene derivatives – except when an –OMe group is present, which adds ca. 9.2 Å²). In addition, the heavy‐atom counts and calculated Log P (“xlogp”) show that all pyridines are relatively lower in lipophilicity (xlogp ≈ 1.4–1.8) compared to the benzene derivatives (typically 2.8–4.3). 

Thus, using the numbers we have we can rationally separate the candidates into three groups:

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Group 1: Heteroaryl (pyridine) halides  
• 2‑bromopyridine (tpsa 12.9, xlogp 1.4)  
• 3‑bromopyridine (tpsa 12.9, xlogp 1.6)  
• 2‑chloropyridine (tpsa 12.9, xlogp 1.2)  
• 3‑chloropyridine (tpsa 12.9, xlogp 1.3)  
• 2‑iodopyridine (tpsa 12.9, xlogp 1.4)  
• 3‑iodopyridine (tpsa 12.9, xlogp 1.8)  

These six share the same polar surface area (≈12.9 Å² from the pyridine N) and low Log P, as expected from a heterocycle.

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Group 2: Benzene derivatives having only “non‐polar” substituents  
(such substituents do not contribute to tpsa – value = 0)  
• 1‑bromo‑4‑ethylbenzene (tpsa 0, xlogp 3.6)  
• 1‑chloro‑4‑ethylbenzene (tpsa 0, xlogp 3.6)  
• 1‑ethyl‑4‑iodobenzene (tpsa 0, xlogp 4.3)  
• 1‑bromo‑4‑(trifluoromethyl)benzene (tpsa 0, xlogp 3.9)  
• 1‑chloro‑4‑(trifluoromethyl)benzene (tpsa 0, xlogp 3.8)  
• 1‑iodo‑4‑(trifluoromethyl)benzene (tpsa 0, xlogp 3.6)

These six have no polar groups on the ring (tpsa = 0) and are moderately lipophilic.

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Group 3: Benzene derivatives bearing a methoxy substituent  
• 1‑bromo‑4‑methoxybenzene (tpsa 9.2, xlogp 2.8)  
• 1‑chloro‑4‑methoxybenzene (tpsa 9.2, xlogp 2.8)  
• 1‑iodo‑4‑methoxybenzene (tpsa 9.2, xlogp 2.9)

Although all benzene derivatives are similar in aromaticity, the –OMe group quantitatively adds about 9.2 Å² to the polar surface area (and lowers the xlogp somewhat), setting these three apart from the “nonpolar” benzene derivatives in Group 2.

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Discussion of the Quantitative Data

• tpsa is a standard descriptor that reflects the presence of polar groups. Here all six pyridines have a tpsa of about 12.9 Å² (owing to the ring N) while all benzene derivatives without an –OMe substituent register 0, and the ones with –OMe show an intermediate tpsa of 9.2.  
• The calculated xlogp values also support our grouping: the heterocycles are less lipophilic (xlogp ca. 1.4–1.8) compared with the more lipophilic benzene derivatives (xlogp between ca. 2.8 and 4.3).  
• Heavy atom counts (7 for the pyridines versus 9 for the benzene ones) further support that these families are structurally distinct.

Since the database numbers (tpsa, xlogp, heavy atom counts) naturally segregate the candidates by both the core ring (pyridine vs benzene) and by the nature of the ring substituent (non‐polar alkyl/–CF₃ vs polar –OMe), the above three groups represent a classification based directly on quantitative measurable properties.

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Final Answer

We classify the fifteen candidate aryl halides into three groups:

• Group 1 (Pyridyl aryl halides):  
 – “2‑bromopyridine”, “3‑bromopyridine”, “2‑chloropyridine”, “3‑chloropyridine”, “2‑iodopyridine”, “3‑iodopyridine”

• Group 2 (Phenyl aryl halides with non‑polar substituents, i.e. ethyl or trifluoromethyl substituents; tpsa = 0):  
 – “1‑bromo‑4‑ethylbenzene”, “1‑chloro‑4‑ethylbenzene”, “1‑ethyl‑4‑iodobenzene”, “1‑bromo‑4‑(trifluoromethyl)benzene”, “1‑chloro‑4‑(trifluoromethyl)benzene”, “1‑iodo‑4‑(trifluoromethyl)benzene”

• Group 3 (Phenyl aryl halides bearing a methoxy substituent; tpsa ≈ 9.2):  
 – “1‑bromo‑4‑methoxybenzene”, “1‑chloro‑4‑methoxybenzene”, “1‑iodo‑4‑methoxybenzene”

This classification relies chiefly on measured/quantitative values (tpsa, xlogp, heavy atom count) as would be found in a comprehensive physicochemical properties database.