Tris- methane, acidity

Mannieh reaction. Detailed directions are available for the preparation of the trifluoroacetate salt (1) by the reaction of bis(dimethy amino)methane with tri-fluoroacetic acid. The reagent (1) was used to effect the regioselective Mannieh reaction of 3-methyl-2-butanone (2) to give the less substituted possible product 3. ... 

Dimethyl ether, methylation by diazo-methane and 2,4,6-trinitroben-zenesulfonic acid to form tri-methyloxomum 2,4,6-tnmtroben zenesulfonate, 46,123 reaction with tnethyloxonium fluo-borate, 46,120... 

TRIS (HYDROXYMETHYL) AMINO-METHANE HYDROCHLORIC ACID 8.07 6.8 to 8.5... 

At the beginning of investigations on chiral dendrimers in our own group was the question of how to synthesize chiral, non-racemic derivatives of tris(hydroxymethyl)-methane [82], which we wanted to use as dendrimer center pieces. We have developed efficient diastereoselective syntheses of such triols [83-85] from ( R)-3-hydroxybutanoic acid, readily available from the biopolymer PHB [59,60] (cf. Sect. 2.4). To this end, the acid is converted to the dioxanone 52 [86, 87], from which various alkylation products and different aldol adducts of type 53 were obtained selectively, via the enolate (Fig. 20). These compounds have been reduced to give a variety of enantiopure chiral building blocks for dendrimers, such as the core unit 54, triply branching units 55a and 55b or doubly branching unit 56 [1,88]. 

Spectrophotometry has been used in the measurement of the dissociation constants of some weak acids using the color of the ion as an indicator. The dissociation constant of tris-(/>-nitrophenyl)-methane in ethanolic sodium ethoxide at 25° is 3.66 X 10-18.848 Another method makes use of the difference in optical rotation between menthol and sodium mentholate to find the position of the equilibrium 844... 

Primary standard tris-(hydroxymethyl)amino methane, also known as THAM or TRIS (FW = 121.14 g/mol), is used to standardize a hydrochloric acid solution. If 0.4922 g of THAM is used and 23.45 mL of HC1 is needed, what is the normality of HC1 ... 

For standardizing acid solutions, primary standard tris-(hydroxymethyl)amino methane, THAM (also referred to as TRIS), can be used. Its formula is... 

A variety of buffers is used in electrophoresis. The selected buffer must contain ions to carry the current. Other than current-carrying capacity, the most critical criterion for buffer selection is the stability of the sample to be analyzed. Many proteins are unstable in acidic pHs, so alkaline buffers are frequently employed. Tris-(hydroxymethyl)amino methane (TRIS or THAM), sodium acetate, and ethylenedi-aminetetraacetate (EDTA) are common solutes in buffers, with pHs between 7.9 and 8.9 typical. (Refer to Chapter 5 for a discussion of buffers.) These buffers also work well with nucleic acid fragments. In addition, phosphate buffers, e.g., 10 mMK3P04, are often used with nucleic acid fragments (1.0 mM = 0.0010 M). 

The presence of symmetry is also an important factor in linear syntheses provided that an element of symmetry is maintained during the course of a synthetic sequence. For instance, one of the syntheses of bullvalene (12) -a molecule that possesses a C3 axis of symmetry- starts from chloroform, and proceeds then through methane(triacetic) acid (9), the corresponding tris-a-diazoketone (10) and bullvalanetrione (11). molecules which all have a C3 axis of symmetry (Scheme 4.3) [16]. 

N-Morpholino]ethanesulfonic acid (MES) Bis[2-hydroxyethyl]iminotris(hydroxymethyl)methane (Bis-Tris) Piperazine-N,N -bis[2-ethanesulfonic acid] (PIPES)... 

The sodium acetate-acetic acid combination is one of the most widely used buffers, and is usually referred to simply as acetate buffer. Other buffer combinations commonly employed in chemistry and biochemistry include carbonate-bicarbonate (sodium carbonate-sodium hydrogen carbonate), citrate (citric acid-trisodium citrate), phosphate (sodium dihydrogen phosphate-disodium hydrogen phosphate), and tris [tris(hydroxymethyl)amino-methane-HCl]. 

Reaction XL. (a) Condensation of a Phenol with a Methane Carbon Atom. (A., 194, 123 196, 77 B., 28, R., 743.)—Phenols can be condensed with compounds which can yield a nuclear carbon, to give dyes of the rosolic acid series. The fewco-compound—tri-hydroxytriphenyl car-binol—first formed, is unstable and immediately yields the dyestuff, no oxidising agent being necessary. In this respect these compounds differ from the analogous rosaniline compounds (see p. 382). 

The acids in which we are interested span a range of roughly 60 pA units, from the strongest acids (HI, HC104) to the weakest (methane, cyclohexane), and since there is no single solvent that is suitable for the entire range, it is necessary to use several different solvents and to try to make connections among the results obtained. 

Acid magenta, acid luchsme, last acid red A 10 De colonsed Colour does not return on exposure to air but is restored by per sul phate Tri phenyl- methane Class H-g, IV erg. 5 K (A 3... 

Formylation of the less reactive phenol and anisole with CO in HF-BF3 was found to require at least stoichiometric amount of the acid for effective transformation (50 equiv. of HF, 2 equiv. of BF3, 50 bar CO, 45°C).445 Conversion increases with increasing reaction time but results in decreasing paralortho ratios suggesting a change from kinetic control to thermodynamic control and the reversibility of formylation. Furthermore, the amount of byproducts (mainly diphenylmethane derivatives) originating from reactions between substrates and products also increases. Additional studies in ionic liquids showed that imidazolium cations with increased chain lengths—for example, l-octyl-3-methylimidazolium salts—are effective in the formylation process. This was attributed to the enhanced solubility of CO in the ionic liquid medium. Tris(dichloromethyl)amine, triformamide, and tris (diformylamino)methane have recently been applied in the formylation of activated aromatic compounds in the presence of triflic acid at low temperature (— 10 to 20°C) albeit yields are moderate.446... 

Fig. 4 Resonant frequency changes with time due to repetitive FIA melamine injections, for the MIP-QCM chemosensor. Melamine concentration is indicated with number at each curve. Inset shows FIA calibration plots for (1) melamine and its interfering compounds, such as (2) ammeline, (3) cyanuric acid, and (4) cyromazine. Volume of the injected sample solution was 100 pL. The flow rate of the 1 mM FIC1 carrier solution was 35 pL min-1. The MIP film was prepared by electropolymerization of 0.3 mM bis(2,2 -bithienyl)-benzo-[18-crown-6]methane functional monomer and 0.3 mM 3,3 -bis[2,2 -bis(2,2 -bithiophene-5-yl)]thianaphthene cross-linking monomer, in the presence of 0.1 mM melamine, in the trihexyl(tetradecyl)phosphonium tris(pentafluor-oethy 1)-trifluorophosphate ionic liquid ACN (1 1 v/v) solution, which was 0.9 mM in trifluoroacetic acid (pH = 3.0). The melamine template was extracted from the MIP film with 0.01 M NaOH before the determinations (adapted from [134])...

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