14039-15-7

Basic information

• Product Name: Methylium, bis(4-methoxyphenyl)phenyl-
• CAS NO: 14039-15-7
• Molecular Formula: C21H19O2
• Molecular Weight: 303.381
• Mol File: 14039-15-7.mol
• Article Data: 9

Chemical Properties

• CAS DataBase Reference: Methylium, bis(4-methoxyphenyl)phenyl-(CAS DataBase Reference)
• NIST Chemistry Reference: Methylium, bis(4-methoxyphenyl)phenyl-(14039-15-7)
• EPA Substance Registry System: Methylium, bis(4-methoxyphenyl)phenyl-(14039-15-7)

Safety Data

• Hazardous Substances Data: 14039-15-7(Hazardous Substances Data)

Upstream product

• 40615-39-2 5'-O-(4-4'-dimethoxytrityl)thymidine 
• 117998-26-2 Thiophosphoric acid O-[(2R,3S,5R)-2-[bis-(4-methoxy-phenyl)-phenyl-methoxymethyl]-5-(5-methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-tetrahydro-furan-3-yl] ester O'-(2,4-dichloro-phenyl) ester S-methyl ester 
• 40615-35-8 4,4'-dimethoxytrityl alcohol 
• 120264-80-4 2,2-bis(4-methoxyphenyl)-2-phenylacetonitrile 

Downstream Products

• 16183-83-8 1-benzyl-3-carbamoylpyridinium ion 
• 611-94-9 4-Methoxybenzophenone 
• 150-76-5 4-methoxy-phenol 
• 136809-03-5 4,4'-dimethoxytritylamine 
• 40615-36-9 4,4'-dimethoxytrityl chloride 
• 40615-35-8 4,4'-dimethoxytrityl alcohol 
• 365-07-1 thymidine 5'-phosphate 

Relevant articles and documents

The 4,4′-dimethoxytrityl carbenium ion by ionization of 4,4′-dimethoxytrityl alcohol in acetonitrile - Aqueous perchloric and nitric acids containing electrolytes: Kinetics, equilibria, and ion-pair formation

We have studied the equilibration shown in eq. [3] of 4,4′-dimethoxytrityl alcohol in aqueous perchloric and nitric acids containing low proportions of acetonitrile using stopped-flow kinetics techniques. The rate constants for the overall progress to equilibrium, kobs, have been resolved into forward and reverse components using the equilibrium UV absorbance and a value for the molar absorptivity of the 4,4′-dimethoxytrityl carbenium ion determined in concentrated aqueous perchloric acid. The forward reaction (rate constant kf) is first order in both the alcohol and the acid concentrations; the reverse reaction (rate constant Kr) is pseudo first order with respect to the carbocation. At constant hydronium ion concentration, the forward rate constant increases linearly with the concentration of electrolyte, whereas the reverse rate constant decreases. These effects depend upon the nature of the anion, but not the cation, and are not ionic strength effects. At constant anion concentrations, kf in both acids, and kr in perchloric acid, are independent of hydronium ion concentration; however, kr decreases with increasing hydronium ion concentration at constant nitrate concentration. At nonconstant ionic strength, changes in kr and Kr observed in increasing concentrations of perchloric acid are attributable wholly to changes in perchlorate concentration. A mechanism is proposed which involves pre-equilibrium protonation of the alcohol, heterolysis of the protonated alcohol to give a 4,4′-dimethoxytrityl carbenium ion - water ion-molecule pair, then conversion of this into a dissociated carbenium ion in equilibrium with ion pairs. To account for the strong effects of perchlorate and nitrate upon the forward rate constants, it is proposed that these anions provide additional reaction channels from the ion-molecule pair. However, we find no evidence of acid catalysis in the reaction of the ion-molecule pair (in contrast to our finding for the reaction of the corresponding ion-molecule pair formed from dimethoxytritylamine in acidic media). Some of the elementary rate and equilibrium constants of the proposed mechanism have been evaluated.

Molar Absorptivity and pKR+ of the 4,4'-Dimethoxytrityl Carbenium Ion in Methanolic Water, and its Equilibrium with Chloride Ion

The 4,4'-dimethoxytrityl carbenium ion has been generated in 80:20 (v/v) water-methanol containing perchloric acid in a rapid reaction from 4,4'-dimethoxytrityl alcohol and in a slower reaction from 4,4'-dimethoxytritylamine.The pK (-0.95; K=8.98) and molar absorptivity (ε=297 000) of the cation have been measured directly under equilibrium conditions in this highly aqueous medium at ionic strength = 1.0 mol dm-3 by a convenient spectrophotometric method at 25 deg C.In addition, the pK has been measured at other temperatures, which allows the determination of the standard enthalpy (ΔH = -11.4 kJ mol-1) and entropy (ΔS = -20 J K-1 mol-1) of the reaction of the cation with the solvent, and at other ionic strengths.The equilibrium constant for the formation of 4,4'-dimethoxytrityl chloride from the cation and chloride has also been measured in the same medium (KRCl = 8.20 at 25.0 deg C, ionic strength = 1.0 mol dm-3) by generating the cation from the alcohol and perchloric acid in the presence of 0.10 mol dm-3 sodium chloride.

Fluorous affinity purification of oligonucleotides

Nucleoside phosphoramidites bearing a fluorous dimethoxytrityl (FDMT) group were used to synthesize fluorous-tagged oligonucleotides, which were subjected to solid-phase extraction using a pH-stable fluorinated adsorbent. On-column detritylation afforded