Bases amines

Ligno sulfonate—metal complexes are weaker complexes than those formed from amine-based complexing agents such as ethylenediaminetetracetic acid (EDTA). They are compatible with most pesticides /herbicides, but thek use in phosphate fertilisers is not recommended. 

AH of the amine hydrogens are replaced when MDA or PMDA reacts with epoxides to form amine based polyols. These polyols can be used in reactions with isocyanates to form urethanes or with additional epoxide to form cross-linked thermo set resins. 

Decomposition to styrene and carbon dioxide has been observed upon heating the acid to temperatures in excess of 150°C. The decarboxylation process can be accelerated with the addition of a bicycHc amine base (9). 

A new family of peroxide-cured dipolymers was introduced in 1991. The peroxide cure provides copolymers that cure faster and exhibit good compression set properties without a postcure. The removal of the cure-site has also made the polymer less susceptible to attack from amine-based additives. By varying the methyl acrylate level in the dipolymer, two offerings in this family have been synthesized, VAMAC D and its more oil-resistant... 

The Fmoc group is cleaved under mild conditions with an amine base to afford the free amine and dibenzofulvene. The approximate half-lives for the. deprotection of Fmoc-ValOH by a variety of amine bases in DMF are as follows ... 

The synthesis of 1-ethoxy-1-butjme has been reported previously, but the preparations have required multistep sequences. Two of the procedures use 1,2-dibromo-l-ethoxy butane which is dehydrohalogenated in two successive steps, first by an amine base and then by either powdered potassium hydroxide or sodium amide no yields are given. The... 

The first two are very soluble in water but the last is less so. Weaker bases inelude ammonium hydroxide where X is NH4. In faet every aeid ean generate a base by loss of a proton and the definition now ineludes any eompound eapable of donating eleetron pairs, e.g. amines. Bases turn litmus paper blue and show eharaeteristie effeets on other indieators. They are soluble in water, tarnish in air, and in eoneentrated form are eorrosive to the toueh. Common examples are given in Table 3.5. ... 

The physical solvent sulfolane provides the system with bulk removal capacity. Sulfolane is an excellent solvent of sulfur compounds such as H2S, COS, and CS2. Aromatic and heavy hydrocarbons and CO2 are soluble in sulfolane to a lesser degree. The relative amounts of DIPA and sulfolane are adjusted for each gas stream to custom fit each application. Sulfinol is usually used for streams with an H2S to CO2 ratio greater than 1 1 or where it is not necessary to remove the CO2 to the same levels as is required for H2S removal. The physical solvent allows much greater solution loadings of acid gas than for pure amine-based systems. Typically, a Sulfinol solution of 40% sulfolane, 40% DIPA and 20% water can remove 1.5 moles of acid gas per mole of Sulfinol solution. 

FIGURE I 1.7 Chromatogram of an amine-based epoxy resin. The analysis of an amine-based epoxy resin was obtained on a column bank of 7.8 x 300 mm Styragel HR O.S, HR I, HR 2, and HR 3 columns. (Courtesy of Waters Corp.)... 

The Friedlander reaction originally was performed in ethanolic alkoxide. Amine bases, such as piperidine, have been used. Anion exchange resins have also been used. ... 

A variety of amine bases were used in 10 mol%, equivalent amount to that of the J ,J -DBF0X/Ph-Ni(C104)2 3H20 catalyst, in the reaction between malononitrile and l-crotonoyl-3,5-dimethylpyrazole in dichloromethane (Scheme 7.48). Not only... 

Metal salt Amine base Solvent TemprC Time/h Yield/% ee %... 

A solution of 5 g of bis(3-methylsulfonyloxypropyl)amine hydrochloride in 20 ml of ice water is neutralized with 1 N sodium carbonate solution. The resulting amine base Is extracted with five 20 ml portions of chloroform. The combined extract is dried over anhydrous sodium sulfate, the solvent is distilled off under reduced pressure, and the residue is dissolved in 20 ml of ethanol. To the ethanol solution Is added slowly with stirring under ice cooling a solution of 2.6 g of p-toluenesulfonic acid in 30 ml of ethanol. The white precipitate formed is collected by filtration and recrystallized from ethanol to give 5.0 g of white crystalline bis-(3-methylsulfonyloxypropyl)amine p-toluenesulfonate melting at 115°C to 116°C. 

Boilers and steam systems Steel steam lines can be inhibited by the use of a volatile amine-based inhibitor such as ammonia, morpholine or cyclohexylamine introduced with the feedwater. It passes through the boiler and into the steam system, where it neutralizes the acidic conditions in pipework. The inhibitor is chemically consumed and lost by physical means. Film-forming inhibitors such as heterocyclic amines and alkyl sulphonates must be present at levels sufficient to cover the entire steel surface, otherwise localized corrosion will occur on the bare steel. Inhibitor selection must take into account the presence of other materials in the system. Some amine products cause corrosion of copper. If copper is present and at risk of corrosion it can be inhibited by the addition of benzotriazole or tolutriazole at a level appropriate to the system (see also Section 53.3.2). 

The new macrocyclic hexaamine ligand X has the mixed protonation constants, log K of 10.10, 10.01, 8.96 and 8.02 at 25 °C and 1=0.2 M for the four most basic amines. The values for other weaker bases, including the six carboxylates, are all less than 5. From a comparison with logA values of the parent macrocycle [18]aneN6, it was deduced that the initial four protonations occur to the macrocyclic amine bases. Thus, the most abundant species of X at neutral pH is depicted as XI. 

The most common method of resolution uses an acid-base reaction between a racemic mixture of chiral carboxylic acids (RC02H) and an amine base (RNH2) to yield an ammonium salt. 

To understand how this method of resolution works, let s see what happens when a racemic mixture of chiral acids, such as (+)- and (-)-lactic acids, reacts with an achiral amine base, such as methylamine, CH3NH2. Stereochemically, the situation is analogous to what happens when left and right hands (chiral) pick up a ball (achiral). Both left and right hands pick up the ball equally well, and the products—ball in right hand versus ball in left hand—are mirror images. In the same way, both ( H- and (-)-lactic acid react with methylamine equally... 

Pyrimidine and imidazole rings are particularly important in biological chemistry. Pyrimidine, for instance, is the parent ring system in cytosine, thymine, and uracil, three of the five heterocyclic amine bases found in nucleic acids An aromatic imidazole ring is present in histidine, one of the twenty amino acids found in proteins. 

E2 elimination then occurs by the usual one-step mechanism as the amine base pyridine abstracts a proton from the neighboring carbon at the same time that the dichlorophosphate group is leaving. 

Amines occur widely in all living organisms. Trimethylamine, for instance, occurs in animal tissues and is partially responsible for the distinctive odor of fish, nicotine is found in tobacco, and cocaine is a stimulant found in the South American coca bush. In addition, amino acids are the buildingblocks from which all proteins are made, and cyclic amine bases are constituents of nucleic acids. 

These equations say that the Kh of an amine multiplied by the of the corresponding ammonium ion is equal to Kw, the ion-product constant for water (1.00 x 10 14). Thus, if we know Ka for an ammonium ion, we also know for the corresponding amine base because /stronger base has an ammonium ion with a larger p... 

What about amine bases In what form do they exist at the physiological pH inside cells—as the amine (A- = RNH2), or as the ammonium ion (HA = RNH3+) Let s take a 0.0010 Vf solution of methylamine at pH = 7.3, for example. According to Table 24.1, the pKa of methvlammonium ion is 10.64, so from the Henderson-Hasselbalch equation, we have... 

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