Triphenylmethane

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title: "Triphenylmethane" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["aromatic-hydrocarbons", "phenyl-compounds", "substances-discovered-in-the-19th-century"] topic_path: "general/aromatic-hydrocarbons" source: "https://en.wikipedia.org/wiki/Triphenylmethane" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 432156972 | ImageFile = Triphenylmethan.svg | ImageSize = 180px | ImageFile1 = Triphenylmethane-3D-balls.png | ImageSize1 = 180px | PIN = 1,1,1-Methanetriyltribenzene | OtherNames = Triphenylmethane 1,1,1-Methylidynetrisbenzene |Section1={{Chembox Identifiers | CASNo_Ref = | CASNo = 519-73-3 | ChEBI_Ref = | ChEBI = 76212 | ChemSpiderID_Ref = | ChemSpiderID = 10169 | EINECS = 208-275-0 | PubChem = 10614 | UNII_Ref = | UNII = 8O4UTW9E17 | InChI = 1/C19H16/c1-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18/h1-15,19H | InChIKey = AAAQKTZKLRYKHR-UHFFFAOYAF | StdInChI_Ref = | StdInChI = 1S/C19H16/c1-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18/h1-15,19H | StdInChIKey_Ref = | StdInChIKey = AAAQKTZKLRYKHR-UHFFFAOYSA-N | SMILES = c1c(cccc1)C(c2ccccc2)c3ccccc3 |Section2={{Chembox Properties | C=19|H=16 | Density = 1.014g/cm3 | MeltingPtC = 92 to 94 | MeltingPt_notes = | BoilingPtC = 359 | Solubility = Insoluble | SolubleOther = Soluble in dioxane and hexane | pKa = 33 | Appearance = Colorless solid | MagSus = −165.6×10−6cm3/mol |Section3={{Chembox Hazards | Hazards_ref= | GHSPictograms = | GHSSignalWord = Warning | HPhrases = | PPhrases = | ExternalSDS = External MSDS| MainHazards = | FlashPt = | AutoignitionPt = Triphenylmethane or triphenyl methane (sometimes also known as Tritan), is the hydrocarbon with the formula (C6H5)3CH. This colorless solid is soluble in nonpolar organic solvents and not in water. Triphenylmethane is the basic skeleton of many synthetic dyes called triarylmethane dyes, many of them are pH indicators, and some display fluorescence. A trityl group in organic chemistry is a triphenylmethyl group Ph3C, e.g. triphenylmethyl chloride (trityl chloride) and the triphenylmethyl radical (trityl radical).

Preparation

Triphenylmethane was first synthesized by heating diphenylmercury (Hg(C6H5)2, Quecksilberdiphenyl) with benzal chloride (C6H5CHCl2, Benzylenchlorid).

It can be synthesized by Friedel–Crafts reaction from benzene and chloroform in the presence of aluminium chloride catalyst: :3 C6H6 + CHCl3 → Ph3CH + 3 HCl Alternatively, benzene may react with carbon tetrachloride using the same catalyst to obtain the triphenylmethyl chloride–aluminium chloride adduct which is then treated with diethyl ether for 24 hours at room temperature and hydrolyzed with concentrated hydrochloric acid: :3 C6H6 + CCl4 + AlCl3 → Ph3CCl·AlCl3 :Ph3CCl·AlCl3 + Et2O + HCl → Ph3CH

It can also be synthesized from benzylidene chloride, which is prepared from benzaldehyde and phosphorus pentachloride.

Reactions of C-H bond

The Ph3C-H bond is relatively weak, with a bond dissociation energy (BDE) of 81 kcal/mol, or about 24 kcal/mol less than methane. Correspondingly, triphenylmethane is relatively acidic, with a pKa of 33.

Triphenylmethane is significantly more acidic than most other hydrocarbons because the charge is delocalized over three phenyl rings. Steric effects however prevent all three phenyl rings from achieving coplanarity simultaneously. Consequently diphenylmethane is even more acidic, albeit only slightly, because in its anion the charge is spread over two phenyl rings at the same time.

The trityl anion is isolable in crown ethers: :[[File:TriphenylmethaneAnion.png|frameless]] Its sodium salt can be prepared from the chloride: :(C6H5)3CCl + 2 Na → (C6H5)3CNa + NaCl

The use of tritylsodium as a strong, non-nucleophilic base has been eclipsed by the popularization of butyllithium and related strong bases.

The unmodified anion is red, and can be used as an indicator in acid–base titrations. Derived substances have proven useful as chemical dyes.

Triarylmethane dyes

Main article: Triarylmethane dye

Examples of triarylmethane dyes are bromocresol green: :[[File:Bromocresol green.svg|200px|Bromocresol green]]

And the nitrogen-bearing malachite green: :[[File:Malachite green structure.svg|250px|Malachite green]]

Trityl group

Protecting group

The triphenylmethyl substituent, also called trityl after a 1927 suggestion by Helferich et al., is widely used in organic chemistry. Trityl serves as a protecting group for alcohols.{{cite journal |doi=10.15227/orgsyn.022.0056|title=β-d-Glucose-1,2,3,4-Tetraacetate|journal=Organic Syntheses|year=1942|volume=22|page=56|author=Delbert D. Reynolds, William Lloyd Evans : protection (requires proton acceptor): Ph3CCl + ROH → Ph3COR + HCl : deprotection: Ph3COR + HBr → ROH + Ph3CBr

Platform for unusual functional groups

Trityl derivatives of reactive functional groups are often crystalline and in some cases sterically stabilized relative to less bulky derivatives. Three such derivatives are S-nitrosotriphenylmethanethiol (Ph3CSNO), tritylsulfenyl chloride (Ph3CSCl), and trityl sulfenamide (Ph3CSNH2).

References

References

  1. "Triphenylmethane {{pipe".
  2. (1872). "Ueber das Triphenylmethan". Berichte der Deutschen Chemischen Gesellschaft.
  3. J. F. Norris. (1925). "Triphenylmethane". Organic Syntheses.
  4. (2017). "The Essential Role of Bond Energetics in C–H Activation/Functionalization". Chemical Reviews.
  5. Ronald Breslow and William Chu. (1969). "Electrochemical determinations of p''K''a's. Triphenylmethanes and cycloheptatriene". Journal of the American Chemical Society.
  6. W. B. Renfrow Jr and C. R. Hauser. (1943). "Triphenylmethylsodium".
  7. Helferich, B.. (1927). "Acylwanderung an partiell acylierten Methyl‐glucosiden". Justus Liebigs Annalen der Chemie.
  8. (1994). "Molecules isoelectronic with 2,2,2-triphenylethanol: Multiple Hydrogen-Bonding Modes in the Structures of O-Tritylhydroxylamine, Ph3CONH2, and Triphenylmethanesulfenamide, Ph3CSNH2". Acta Crystallographica Section C Crystal Structure Communications.

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