Acetone amino

Amino acetone is not a stable compound. It can be made from acetone by nitrosation and reduction whereupon it dimerises to give (48). 

Pyrazines are formed from transamination reactions, in addition to carbon dioxide and formaldehyde. A requirement is that the carbonyl compound contains a dione and the amino group is alpha to the carboxyl group (16). If the hydrogen on the ct-carbon oI the amino acid is substituted, a ketone is produced. Newell (17) initially proposed a pyrazine formation mechanism between sugar and amino acid precursors. (See Figure 3). The Schiff base cation is formed by addition of the amino acid to the anomeric portion of the aldo-hexose, with subsequent losses of vater and a hydroxyl ion. Decarboxylation forms an imine which can hydrolyze to an aldehyde and a dienamine. Enolization yields a ketoamine, vhich dissociates to amino acetone and glyceraldehyde. 2,5-Dimethylpyrazine is formed by the condensation of the tvo molecules of amino acetone. 

C6H12 3-methyl-trans-2-pentene 616-12-6 343.60 29 288 1,2 8351 C6H12N203 1-(((2-hydroxypropyl)nitroso)amino)acetone 61499-28-3 319.75 26.875 1,2... 

In the reaction of cij-[Co(en)2(NH2CH2R)(NH2CH2COMe)] ion with base, imine complexes (11) are formed by condensation of the co-ordinated amino-acetone with the NH2 group of co-ordinated en and not with the co-ordinated RCH2NH2 (L). Favourable orientation of the carbonyl group is invoked to... 

The enzyme catalyzing the condensation of two molecules of 5-AL to one of PBG (Fig. 11) is widely distributed in animal tissues (72-75), and the use of 5-AL in porphyrin biosynthesis has been shown in spinach (74), yeast (74), and bacteria (59, 74, 76). The preparation from ox liver (74) and that from rabbit reticulocytes (75) have been considerably purified and show very similar characteristics. The enzyme from ox liver is rather specific for its substrate. 2,5-Diamino-4-ketopentanoic acid, 6-amino-5-ketohexanoic acid, and aminoacetone form no pyrrole with this enzyme, and are only weakly inhibitory if at all. The rabbit enzyme does not act on amino acetone, nor does it seem to form a mixed pyrrole in the presence of both 5-AL and aminoacetone. The kinetics of this enzyme are of interest since it is a rare case of an enzyme catalyzing a reaction between two identical. substrate molecules. Both the rabbit and ox liver enzymes follow simple Michaelis kinetics over the range 10 to 2 X M substrate concentration. The simplest interpretation of these data, together with some related chemical evidence (75), is that the enzyme binds both molecules of substrate specifically, the first more tightly than the second. In this respect it resembles most the enzyme-coenzyme substrate reactions. The reaction... 

Amino-4 -methylthiazole slowly decomposes on storage to a red viscous mass. It can be stored as the nitrate, which is readily deposited as pink crystals when dilute nitric acid is added to a cold ethanolic solution of the thiazole. The nitrate can be recrystallised from ethanol, although a faint pink colour persists. Alternatively, water can be added dropwise to a boiling suspension of the nitrate in acetone until the solution is just clear charcoal is now added and the solution, when boiled for a short time, filtered and cooled, deposits the colourless crystalline nitrate, m.p. 192-194° (immersed at 185°). The thiazole can be regenerated by decomposing the nitrate with aqueous sodium hydroxide, and extracting the free base with ether as before. 

Thus in neutral medium the reactivity of 2-aminothiazoles derivatives toward sp C electrophilic centers usually occurs through the ring nitrogen. A notable exception is provided by the reaction between 2-amino-thiazole and a solution (acetone-water, 1 1) of ethylene oxide (183) that yields 2-(2-hydroxyethylamino)thiazole (39) (Scheme 28), Structure 39... 

The ability of various selenium heterocycles to check the loss of orthophosphate caused by irradiation of ATP has been studied by Brucker and Bulka (92). They found that only 2-amino-4,5-dimethyiselenazole shows radioprotective properties, while other 2-aminoselenazoles, selenosemicarbazides, and acetone selenosemicar-bazones possess no such activity but are in addition very sensitive to radiation (93). 

Ethanol, acetaldehyde, acetic acid, acetone, glycerol, n - butanol, n - butyric acid, amyl alcohols, oxalic acid, lactic acid, citric acid, amino acids, antibiotics, vitamins... 

Amino-2-hydroxybenZOiC acid. This derivative (18) more commonly known as 4-aminosa1icy1ic acid, forms white crystals from ethanol, melts with effervescence and darkens on exposure to light and air. A reddish-brown crystalline powder is obtained on recrystallization from ethanol —diethyl ether. The compound is soluble ia dilute solutioas of nitric acid and sodium hydroxide, ethanol, and acetone slightly soluble in water and diethyl ether and virtually insoluble in benzene, chloroform or carbon tetrachloride. It is unstable in aqueous solution and decarboxylates to form 3-amiaophenol. Because of the instabihty of the free acid, it is usually prepared as the hydrochloride salt, mp 224 °C (dec), dissociation constant p 3.25. 

The outstanding chemical property of cyanohydrins is the ready conversion to a-hydroxy acids and derivatives, especially a-amino and a,P-unsaturated acids. Because cyanohydrins are primarily used as chemical intermediates, data on production and prices are not usually pubUshed. The industrial significance of cyanohydrins is waning as more direct and efficient routes to the desired products are developed. Acetone cyanohydrin is the world s most prominent industrial cyanohydrin because it offers the main route to methyl methacrylate manufacture. 

Hydroxyl Group. The OH group of cyanohydrins is subject to displacement with other electronegative groups. Cyanohydrins react with ammonia to yield amino nitriles. This is a step in the Strecker synthesis of amino acids. A one-step synthesis of a-amino acids involves treatment of cyanohydrins with ammonia and ammonium carbonate under pressure. Thus acetone cyanohydrin, when heated at 160°C with ammonia and ammonium carbonate for 6 h, gives a-aminoisobutyric acid [62-57-7] in 86% yield (7). Primary and secondary amines can also be used to displace the hydroxyl group to obtain A/-substituted and Ai,A/-disubstituted a-amino nitriles. The Strecker synthesis can also be appHed to aromatic ketones. Similarly, hydrazine reacts with two molecules of cyanohydrin to give the disubstituted hydrazine. 

Cyanohydrin Synthesis. Another synthetically useful enzyme that catalyzes carbon—carbon bond formation is oxynitnlase (EC 4.1.2.10). This enzyme catalyzes the addition of cyanides to various aldehydes that may come either in the form of hydrogen cyanide or acetone cyanohydrin (152—158) (Fig. 7). The reaction constitutes a convenient route for the preparation of a-hydroxy acids and P-amino alcohols. Acetone cyanohydrin [75-86-5] can also be used as the cyanide carrier, and is considered to be superior since it does not involve hazardous gaseous HCN and also virtually eliminates the spontaneous nonenzymatic reaction. (R)-oxynitrilase accepts aromatic (97a,b), straight- (97c,e), and branched-chain aUphatic aldehydes, converting them to (R)-cyanohydrins in very good yields and high enantiomeric purity (Table 10). 

Only 2-alkylthiopyrimidines are made by the Principal Synthesis, using 5-alkylthiourea as one component. For example, ethoxymethylenemalononitrile (877) and 5-benzylthiourea in aqueous acetone at 20 °C give 4-amino-2-benzylthiopyrimidine-5-carbonitrile (878) (61JOC79) and ethyl 2-allyl-2-formylacetate and 5-methylthiourea in aqueous ethanolic alkali give 5-allyl-2-methylthiopyrimidin-4(3H)-one (6UOC4425). 

The 6/3-amino group of 6-APA may be alkylated either with diazoalkanes <67LA(702)163) or by the reduction of Schiff bases (Scheme 50) (65JCS3616). Two special cases of N-alkylation are also shown in Scheme 50 the formation of an imidazolidinone ring upon treating ampicillin with acetone (66JOC897), and the formation of a 6/3-amidinopenicillanic acid from 6-APA (77MI51105). 

Cosolvents ana Surfactants Many nonvolatile polar substances cannot be dissolved at moderate temperatures in nonpolar fluids such as CO9. Cosolvents (also called entrainers, modifiers, moderators) such as alcohols and acetone have been added to fluids to raise the solvent strength. The addition of only 2 mol % of the complexing agent tri-/i-butyl phosphate (TBP) to CO9 increases the solubility ofnydro-quinone by a factor of 250 due to Lewis acid-base interactions. Veiy recently, surfac tants have been used to form reverse micelles, microemulsions, and polymeric latexes in SCFs including CO9. These organized molecular assemblies can dissolve hydrophilic solutes and ionic species such as amino acids and even proteins. Examples of surfactant tails which interact favorably with CO9 include fluoroethers, fluoroacrylates, fluoroalkanes, propylene oxides, and siloxanes. 

Amino-4,6-dimethylpyrimidine [767-15-7] M 123.2, m 152-153 , pK 4.95. Crystn from water gives m 197°, and crystn from acetone gives m 153°. 

Amino-4-methyIpyridine [695-34-1 ] M 108.1, m 99.2 , b 230 , pK 7.48. Crystd from EtOH or a 2 1 benzene/acetone mixture, and dried under vacuum. 

Amino-6-methyIpyridine [1824-81-3] M 108.1, m 44.2 , b 208-209 , pK 7.41. Crystd three times from acetone, dried under vacuum at ca 45 . After leaving in contact with NaOH pellets for 3h, with occasional shaking, it was decanted and fractionally distd [Mod, Magne and Skau J Phys Chem 60 1651 1956]. Also recrystd from CH2CI2 by addition of pet ether. [Marzilli et al. J Am Chem Soc 108 4830 1986.]... 

Definitive identification of lysine as the modified active-site residue has come from radioisotope-labeling studies. NaBH4 reduction of the aldolase Schiff base intermediate formed from C-labeled dihydroxyacetone-P yields an enzyme covalently labeled with C. Acid hydrolysis of the inactivated enzyme liberates a novel C-labeled amino acid, N -dihydroxypropyl-L-lysine. This is the product anticipated from reduction of the Schiff base formed between a lysine residue and the C-labeled dihydroxy-acetone-P. (The phosphate group is lost during acid hydrolysis of the inactivated enzyme.) The use of C labeling in a case such as this facilitates the separation and identification of the telltale amino acid. 

This ester was developed to impart greater hydrophilicity in C-terminal peptides that contain large hydrophobic amino acids, since the velocity of deprotection with enzymes often was reduced to nearly useless levels. Efficient cleavage is achieved with the lipase from R. niveus (pH 7, 37°, 16 h, H2O, acetone, 78-91% yield)... 

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