Triethylamine basicity

Basic catalysts other than alkali acetates have been employed in the Perkin reaction thus salicylaldehyde condenses with acetic anhydride in the presence of triethylamine to yield coumarin (tlie lactone of the cis form of o-hydroxy-cinnamio acid) together with some of the acetyl derivative of the trans form (o-acetoxycoumaric acid) ... 

The mechanism of the reaction, which is of the aldol type, involves the car-bonyl group of tlie aldehyde and an active methylene group of the anhydride the function of the basic catalyst B (acetate ion 0H3000 or triethylamine N(0,Hb)j) is to form the anion of the active hydrogen component, i.e., by the extraction of a proton from the anhydride ... 

The a-carbon atom of the phenylacetyl group is more susceptible to attack by the basic catalyst (triethylamine) than the acetyl group hence a-phenyl-cinnamic acid, but no cinnamic acid, is obtained. 

Coumarin. In a 250 ml. round-bottomed flask, provided with a small reflux condenser and a calcium chloride drying tube at the top, place 2 1 g, of salicylaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of acetic anhydride, and reflux the mixture gently for 12 hours. Steam distil the mixture from the reaction flask and discard the distillate. Render the residue in the flask basic to litmus with solid sodium bicarbonate, cool, filter the precipitated crude coumarin at the pump and wash it with a little cold water. Acidify the filtrate to Congo red with... 

Alternatively, use the following procedure in which triethylamine replaces potassium acetate as the basic catalyst. Place 2 1 g. (2-0 ml.) of purified benzaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of A.R. acetic anhydride in a 200 ml. round-bottomed flask, equipped with a short reflux condenser and a calcium chloride drying tube. Boil the solution gently for 24 hours—heating may be interrupted. Incorporate a steam distillation apparatus in the flask and steam distil until the distillate is no longer cloudy (about 100 ml.) and then collect a further 50 ml. of the distillate di ard the steam distillate. Transfer the residue in the flask to a 400 ml. beaker, add water until the vplume is about 200 ml., then 0 2 g. of decolourising carbon, and boil for a few minutes. Filter the hot solution, and acidify the hot filtrate with 1 1 hydrochlorioiaoid... 

Soluble analogues of these difunctional initiators have been prepared either by addition of small amounts of weakly basic additives such as triethylamine (73) or anisole (74) which have relatively minor effects on diene microstmcture (37). Another method to solubilize these initiators is to use a seeding technique, whereby small amounts of diene monomer are added to form a hydrocarbon-soluble, oligomeric dilithium-initiating species (69,75). 

When the catalyst is triethylamine, the yield is nearly 100% cycHc oligomers but if pyridine is used, the polymer is nearly 100% linear. A basic catalyst in the second step, such as lithium stearate or an organic titanate [bis-(acetylacetonato)diisopropoxytitanium], produces a polycarbonate with a molecular weight of 250,000—300,000 when polymerized at 300°C for 30 min. A fiber glass composite has been prepared using this basic procedure (39). 

With more strongly basic tertiary amines such as triethylamine, another mechanism can come into play. It has been found that wften methanol deuterated on oxygen reacts with acyl chlorides in the presence of triethylamine, some deuterium is found a to the carbonyl group in the ester... 

In the acylation of enamines, the weakly basic acylated enamine does not absorb the acid formed. Consequently, one must employ 2 equivalents of the enamine or use a second tertiary amine to absorb the acid liberated. In the procedure, triethylamine is employed to absorb the hydrochloric acid. 

Note. For primary amines in the pK range 10-11, triethylamine (2eq.) suffices as base for less-basic amines, n-BuLi (2 eq.) must be used. 

Most thiirene dioxides (and oxides) have been prepared through a modified Ramberg-Backlund reaction as the last crucial cyclization step, as illustrated in equation 40 for the benzylic series . Synthesis of thiirene dioxides requires two major modifications of the originally employed reaction first, the inorganic base has to be replaced by the less basic and less nucleophilic triethylamine - and second, the aqueous media has to be substituted by an aprotic organic solvent (e.g. methylene chloride). Under these mild reaction conditions the isolation of aryl-substituted thiirene dioxides (and oxides) is feasible . In fact, this is the most convenient way for the preparation of the aryl-disubstituted three-membered ring sulfones and sulfoxides. ... 

If the analyte contains either an acidic or a basic functionality, adjusting the pH of the extraction solvent to make the analyte either ionic or nonionic may be advantageous. To make an analyte that contains an acidic or basic functionality nonionic for extraction into a nonpolar solvent, a small amount (5% or less) of an organic acid (such as acetic acid or trifluoroacetic acid) or organic base (triethylamine) along with methanol (about 10%) can be added to diethyl ether or ethyl acetate. Conversely, buffered solutions can be used to control the pH precisely in such a way as to control the charge on an analyte and thus improve its extraction efficiency into polar solvents. 

Triethylamine (TEA) is sometimes used as an additive for signal enhancement. However, in the positive ESI mode, TEA readily ionizes to give an intense [M + H]+ ion at miz 102. This then suppresses the ionization of the less basic compounds in the positive ESI mode. In the negative mode, TEA can enhance ionization for certain compounds because of its basic properties. 

To synthesize new surfactants, having incorporated both structural elements, the known siloxanyl modified halogenated esters and ethers of dicyclopentadiene [5] were treated with different amines according to the reaction scheme. Triethylamine yielded quaternary ammonium salts directly. Alternatively, after reaction with diethylamine or morpholine, the isolated siloxanyl-modified tertiary amines were also converted to quaternary species. To obtain anionic surfactants, the halogenated precursors were initially reacted with n-propylamine. In subsequent reaction steps the secondary amines formed were converted with maleic anhydride into amides, and the remaining acid functions neutralized. Course and rate of each single reaction strongly depended on the structure of the initial ester or ether compound and the amine applied. The basicity of the latter played a less important role [6]. 

The sparingly water-soluble triethylammonium saltofBi2H122-is readily converted to the highly water-soluble sodium salt. A carefully weighed sample of the triethylammonium salt is treated with an exactly equivalent amount of standardized aqueous sodium hydroxide. The mixture is heated to effect solution and then boiled to expel the free triethylamine until the vapors are no longer basic. Evaporation to dryness then leaves a crystalline hydrate of Na2Bi2Hi2. The anhydrous salt is obtained by drying at 100°/1 n for 24 hours and has characteristic infrared absorption frequencies as a Nujol mull (exclusive of any frequencies coincident with Nujol) at 2470 (s), 1010 (w), 1070 (m), 770 (w), 727 (m),710 (m),and 700 (m) cm. 1... 

R = H, X = S, A = Et3N and Py). In solution the former is mainly in an ionic form the latter exists as a complex. The basicity of the amine is assumed to be important. Triethylamine is a stronger base than pyridine and the ionic form is stabilized. When the proton affinity is weak, the basicity in relation to the B(III) atom, a Lewis acid, plays an important role. This involves an equilibrium shift toward the complex. This assumption is confirmed by an easy displacement of pyridine by triethylamine. The reverse process demands more severe conditions. In the NMR spectra of the triethylamine complex the signal is shifted from 22 to 42 ppm as pyridine is added. The absence of signals of two separate forms is evidence in favor of their fast interconversion. The chemical shift of the signal in 3IP spectra is 22 ppm (EtOH), 26 ppm (Py, DMFA), and 42 ppm (EtOH, Py) for complexes with triethylamine and pyridine. 

As seen in Table V, there is a clear dependence of the equilibrium position on the basicity of amines, excluding triethylamine. However, it is necessary to take into account not only the proton affinity of the amine, but also the ability of the amine to form a dative bond with a boron atom. The equilibrium position also depends on the structure of the phosphorus-... 

The reaction has been improved to a satisfactory process by modifying the reaction conditions. A remarkable effect of the addition of amines on the reaction was observed (49). For example, the reaction of butadiene (4 moles) and acetic acid (4 moles) in the presence of 2-(N,/V-dimethyl-amino)ethanol (4 moles) using Pd(acac)2 (3 mmoles) and PPh3 (3 mmoles) at 90°C gave complete conversion after 2 hours. The product was found to consist of 8-acetoxy-1,6-octadiene (47) (71%), 3-acetoxy-1,7-octadiene (48) (21%) and 1,3,7-octatriene (16) (8%). Various tertiary amines, such as triethylamine, )V-methylmorpholine, Af,Af,N, N -tetramethyl-1,3-bu-tanediamine, and triethylenediamine, showed the same favorable effect. Other basic salts, such as sodium and potassium acetate, accelerate the reaction, especially at high concentrations (50, 51). The selection of solvents is also important. Arakawa and Miyake found that electron-donating type solvents (e.g., THF and triethylamine) are good solvents... 

Selective reaction at the ci.s-2,3-diol grouping of unprotected D-ribonucleosides has occasionally been observed. Treatment of D-ribonucleosides with tris(tetramethylammonium) trimetaphosphate in M sodium hydroxide for 4 days at room temperature led to a mixture of nucleoside 2 - and 3 -phosphates in yields of >70% no 5 -phosphate was detected.213 Reaction of ethyl (trichloromethyl)phos-phonate with nucleosides in N,N-dimethylformamide containing triethylamine, followed by basic hydrolysis of the reaction product, yielded 2 (3 )-phosphates in variable yields.214 The participation of the cis-diol grouping in the reaction was suggested by the failure of thymidine or 2, 3 -0-isopropylideneuridine to undergo reaction. 

Aldehyde 26 was treated with hydroxylamine hydrochloride in refluxing methanol to give a mixture of (E)- and (Z)-pyrrolotriazine 40 in 59% and 21% yield, respectively. Dehydration of aldoxime 40 with trifluoromethanesulfonic anhydride and triethylamine in dichloromethane afforded triazine 41. Conversion of the nitrile 41 to the deprotected amide 42 was accomplished in 96% yield on treatment of 41 with basic hydrogen peroxide in ethanol <2001CAR77>. 

Basic compounds Amines Phosphate buffer, triethylamine (buffered to pH 3.0)... 

Competing amines such as triethylamine and di-rc-butylamine have been added to the mobile phase in reversed-phase separations of basic compounds. Acetic acid can serve a similar purpose for acidic compounds. These modifiers, by competing with the analyte for residual active sites, cause retention time and peak tailing to be reduced. Other examples are the addition of silver ions to separate geometric isomers and the inclusion of metal ions with chelating agents to separate racemic mixtures. 

B. 2,2-(Trimethylenedithio)cyclohexanone. A solution of 3.02 g. (0.02 mole) of freshly distilled 1-pyrrolidinocyclohexene, 8.32 g. (0.02 mole) of trimethylene dithiotosylate4 (Note 2), and 5 ml. of triethylamine (Note 3) in 40 ml. of anhydrous acetonitrile (Note 4), is refluxed for 12 hours in a 100-ml., round-bottom flask under a nitrogen atmosphere. The solvent is removed under reduced pressure on a rotary evaporator, and the residue is treated with 100 ml. of aqueous 0.1 N hydrochloric acid for 30 minutes at 50° (Note 5). The mixture is cooled to ambient temperature and extracted with three 50-ml. portions of ether. The combined ether extracts are washed with aqueous 10% potassium bicarbonate solution (Note 6) until the aqueous layer remains basic to litmus, and then with saturated sodium chloride solution. The ethereal solution is dried over anhydrous sodium sulfate, filtered, and concentrated on a rotary evaporator. The resulting oily residue is diluted with 1 ml. of benzene and then with 3 ml. of cyclohexane. The solution is poured into a chromatographic column (13 x 2.5 cm.), prepared with 50 g. of alumina (Note 7) and a 3 1 mixture of cyclohexane and benzene. With this solvent system, the desired product moves with the solvent front, and the first 250 ml. of eluent contains 95% of the total product. Elution with a further 175 ml. of solvent removes the remainder. The combined fractions are evaporated, and the pale yellow, oily residue crystallizes readily on standing. Recrystallization of this material from pentane gives 1.82 g. of white crystalline 2,2-(trimethylenedithio)cyclo-hexanone, m.p. 52-55° (45% yield) (Note 8). 

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