4-(Trifluoromethyl)phenylboronic Acid | CAS 128796-39-4 | ≥98%

4-(Trifluoromethyl)phenylboronic Acid (4-(trifluoromethyl)benzeneboronic acid, α,α,α-trifluoro-p-tolylboronic acid, p-(trifluoromethyl)phenylboronic acid) carries a para-trifluoromethyl group that is strongly electron-withdrawing (σp +0.54), with σ-induction and hyperconjugative withdrawal through the C–F bonds the dominant electronic contributions, distinct from halogen substituents that combine inductive withdrawal with resonance donation. The measured boronic-acid pKa is 7.85 in water, well below phenylboronic acid (≈ 8.9), and trifluoromethylphenylboronic-acid isomers have been reported to show high resistance to protodeboronation, distinguishing the para-CF3 substrate from more labile electron-poor arylboronic acids. The CF3 group is robust under typical synthesis conditions and is retained intact in coupled products, where it tunes lipophilicity, polarity, and electronic character of derived molecules; the three equivalent fluorines also provide a strong, sharp 19F NMR reporter for tracking species in solution and in mechanistic studies. Used as a 4-(trifluoromethyl)phenyl building block in medicinal chemistry, agrochemicals, fluorinated π-conjugated materials, and OLED host and emitter intermediates.

May contain small amounts of the cyclic anhydride 4-(trifluoromethyl)phenylboroxine. Under aqueous or basic coupling conditions the two forms re-equilibrate and the impact on yield is minor.

Applications and Reactions

• Suzuki–Miyaura coupling: with aryl, heteroaryl, or alkenyl electrophiles to give 4-(trifluoromethyl)biaryl, 4-CF3-arylheteroaryl, terphenyl, and aryl-alkenyl products. The strong electron-withdrawing CF3 group changes boronate speciation, while published trifluoromethylphenylboronic-acid studies report high resistance to protodeboronation; catalyst, base, solvent, and temperature still govern practical coupling performance.
• CF3 as property modulator in coupled products: the retained para-trifluoromethyl group is robust under many synthetic conditions and is used to tune lipophilicity, polarity, and electronic character in medicinal-chemistry, agrochemical, and materials scaffolds; effects on permeability, conformation, and metabolic stability remain structure-dependent in the final molecule.
• 19F NMR handle and mechanistic probe: the three equivalent fluorines of the CF3 group give a convenient 19F NMR reporter for the 4-CF3-phenyl unit. 4-(Trifluoromethyl)phenylboronic acid has been used as a 19F NMR probe in mechanistic studies of Pd-catalysed arylboronic-acid self-coupling and transmetalation chemistry.
• Chan–Lam coupling: copper-mediated arylation onto N and O nucleophiles, including amines, amides, sulfonamides, carbamates, N–H heterocycles, phenols, and selected alcohols.
• Petasis borono-Mannich reaction: three-component coupling with an amine and a carbonyl partner to give α-aryl amines, α-amino acids, or β-amino alcohols bearing the 4-(trifluoromethyl)phenyl group, metal-free.
• Rhodium-catalysed asymmetric 1,4-addition: reported in Rh-catalysed enantioselective conjugate-addition chemistry of arylboronic acids, transferring the 4-(trifluoromethyl)phenyl group to activated alkene acceptors under chiral ligand control; exact substrate class and ligand choice are method-dependent.
• Palladium-catalysed direct arylation: reported as the 4-CF3-aryl source in Pd-catalysed direct C–H arylation of arenes and heteroarenes, including site-selective and regioselective protocols.
• Tandem Pd(II) oxidative Heck / C–H amidation: reported in tandem-type Pd(II)-catalysed oxidative Heck arylation followed by intramolecular C–H amidation sequences for heterocycle construction.
• Ruthenium-catalysed direct arylation: reported for 4-(trifluoromethyl)phenyl arylboronate derivatives in Ru-catalysed arylation of benzylic sp³ C–H positions of directed acyclic amines (typically using a 3-substituted pyridyl directing group), giving α-aryl-amine scaffolds.
• Pd-catalysed allylation and Cu-catalysed N-arylation: reported in Pd-catalysed direct cross-coupling with allyl alcohols to give allylated 4-(trifluoromethyl)phenyl products, and in N-arylation of imidazoles and amines using copper-exchanged fluorapatite as a heterogeneous catalyst.
• Microwave-promoted Pd cross-coupling with acid chlorides: reported in microwave-accelerated Pd-catalysed coupling of arylboronic acids with acid chlorides, especially aroyl chlorides, to give 4-(trifluoromethyl)phenyl aryl ketones.
• Fluorinated π-conjugated materials: Suzuki–Miyaura building block for installing the 4-CF3-phenyl unit into electron-poor π-conjugated scaffolds, including thiazolo[5,4-d]thiazole derivatives reported for printable-electronics research and patent-reported CF3-substituted anthracene–carbazole architectures such as CF3CzPA. The CF3 group contributes electron-withdrawing character, polarity, and chemical robustness, while device-level optical and transport effects remain scaffold-dependent.
• Protected boronate esters: precursor to pinacol (Bpin), neopentyl glycol, MIDA, and 1,8-diaminonaphthalene (Bdan) esters when more chromatographically tractable 4-(trifluoromethyl)aryl–boron building blocks are required for iterative cross-coupling.
• Non-classical arylation: Suzuki–Miyaura-type coupling with arenediazonium tetrafluoroborates as alternative aryl electrophiles.
• Ipso-nitration: reported in copper-mediated nitration chemistry of arylboronic acids, replacing the boronic-acid group with nitro to access nitrobenzotrifluoride-type products from the 4-CF3 arylboronic-acid scaffold; other ipso-nitration protocols are also known across the broader arylboronic-acid class.
• Ipso-halodeboronation: deborylative bromination, chlorination, or iodination of arylboronic acids can replace the boronic-acid group with halogen; for the 4-(trifluoromethyl) substrate this gives access to 4-halobenzotrifluorides such as 4-bromobenzotrifluoride, 4-chlorobenzotrifluoride, or 4-iodobenzotrifluoride, depending on halogen source and conditions.
• Oxidative ipso-hydroxylation: peroxide- or perborate-mediated conversion to 4-(trifluoromethyl)phenol under mild arylboronic-acid hydroxylation conditions; aerobic photoredox and copper-catalysed variants are broader arylboronic-acid method classes.

Further Reading

For boronic acids, boronic esters, protodeboronation, boroxine content, and Suzuki–Miyaura reagent selection, see NorrChemica's Lab Journal guide: Choosing Your Boron Source for Suzuki–Miyaura Coupling.