Hydrates amides

The use of the transition-state analogue concept is an effective approach in the design of potent enzyme inhibitors. For the aspartyl proteases, structures that mimic the tetrahedral hydrated amide formed during the peptidic bond hydrolysis led to the preparation of compounds with very high binding affinity to the enzymes. In the... 

CCls CHO. A colourless oily liquid with a pungent odour b.p. 98°C. Manut actured by the action of chlorine on ethanol it is also made by the chlorination of ethanal. When allowed to stand, it changes slowly to a white solid. Addition compounds are formed with water see chloral hydrate), ammonia, sodium hydrogen sulphite, alcohols, and some amines and amides. Oxidized by nitric acid to tri-chloroethanoic acid. Decomposed by alkalis to chloroform and a methanoate a convenient method of obtaining pure CHCI3. It is used for the manufacture of DDT. It is also used as a hypnotic. 

For those nitriles which yield water-insoluble amides e.g., the higher alkyl cyanides), hydrolysis to the amide often leads to a satisfactory derivative. The hydration is eflfected by warming a solution of the nitrile in concentrated sulphuric acid for a few minutes, cooling and pouring... 

Nitriles may often be hydrolysed (hydrated) to the amides (RCN— RCONHj) by concentrated sulphuric acid or by concentrated hydrochloric acid, usually in the cold or at 40° (see Sections III,115 and IV,160). The resulting amide is, of course, a useful derivative. 

The heat of hydration is approximately —70 kj /mol (—17 kcal/mol). This process usually produces no waste streams, but if the acrylonitrile feed contains other nitrile impurities, they will be converted to the corresponding amides. Another reaction that is prone to take place is the hydrolysis of acrylamide to acryhc acid and ammonia. However, this impurity can usually be kept at very low concentrations. American Cyanamid uses a similar process ia both the United States and Europe, which provides for their own needs and for sales to the merchant market. 

Lauramide has been prepared by passing ammonia gas through lauric acid in the presence of metallic oxides, specifically a complex mixture of Si02—AI2O2—Fe202—CaO—SO in the ratio of 24 16 3 47 10. The oxides, which are hydrated during amidation, can be regenerated by calcination (12,13). 

The hydration of nitriles has been used to synthesize amides, for example, by treating stearonittile in ether with dry hydrochloric acid followed by the addition of water to give a 73—94% yield of stearamide or its hydrochloride (25). The long reaction time at 0°C and the use of ether make this route of tittle commercial value. 

Thorium compounds of anionic nitrogen-donating species such as [Th(NR2)4], where R = alkyl or sdyl, are weU-known. The nuclearity is highly dependent on the steric requirements of R. Amides are extremely reactive, readily undergoing protonation to form amines or insertion reactions with CO2, COS, CS2, and CSe2 to form carbamates. Tetravalent thorium thiocyanates have been isolated as hydrated species, eg, Th(NCS)4(H20)4 [17837-16-0] or as complex salts, eg, M4 Th(NCS)g] vvH20, where M = NH, Rb, or Cs. 

Zinc chloride melts at 275°C, bods at 720°C, and is stable in the vapor phase up to 900°C. It is very hygroscopic, extremely water-soluble, and soluble in organic Hquids such as alcohols, esters, ketones, ethers, amides, and nitrides. Hydrates with 1, 1.5, 2.5, 3, and 4 molecules of water have been identified and great care must be exercised to avoid hydration of the anhydrous form. Aqueous solutions of zinc chloride are acidic (pH = 1.0 for 6 M) and, when partially neutralized, can form slightly soluble basic chlorides, eg, ZnCl2 4Zn(OH)2 [11073-22-6] and Zn(OH)Cl [14031-59-5]. Many other basic chlorides have been reported (58). 

There are two distinct classes of enzymes that hydrolyze nitriles. Nittilases (EC 3.5.5. /) hydrolyze nittiles directiy to corresponding acids and ammonia without forming the amide. In fact, amides are not substrates for these enzymes. Nittiles also may be first hydrated by nittile hydratases to yield amides which are then converted to carboxyUc acid with amidases. This is a two-enzyme process, in which enantioselectivity is generally exhibited by the amidase, rather than the hydratase. 

The aminolysis of esters of pyrimidine occurs normally to yield amides. The reagent is commonly alcoholic ammonia or alcoholic amine, usually at room temperature for 20-24 hours, but occasionally under refiux aqueous amine or even undiluted amine are used sometimes. The process is exemplified in the conversion of methyl pyrimidine-5-carboxylate (193 R = Me) or its 4-isomer by methanolic ammonia at 25 °C into the amide (196) or pyrimidine-4-carboxamide, respectively (60MI21300), and in the butylaminolysis of butyl ttracil-6-carboxylate (butyl orotate) by ethanolic butylamine to give A-butyluracil-5-carboxamide (187) (60JOC1950). Hydrazides are made similarly from esters with ethanolic hydrazine hydrate. 

The NMR spectra of both the parent [2,3-f ] and [3,4-f ] pyridopyrazine systems have been analyzed (66JCS(C)999). Shift values are given in Table 3. These studies were extended to the phenomenon of covalent hydration in both systems (66JCS(C)999,79JHC301) (see Section 2.15.13.2), as well as the addition of other nucleophiles such as amide ion (79JHC301, 79JHC305). 

Triazole has been prepared by the oxidation of substituted 1,2,4-triazoles, by the treatment of urazole with phosphorus pentasulfide, by heating equimolar quantities of formyl-hydrazine and formamide, by removal of the amino function of 4-amino-l,2,4-triazole, by oxidation of l,2,4-triazole-3(5)-thiol with hydrogen peroxide, by decarboxylation of 1,2,4-triazole-3(5)-carboxylic acid, by heating hydrazine salts with form-amide,by rapidly distilling hydrazine hydrate mixed with two molar equivalents of formamide, i by heating N,N -diformyl-hydrazine with excess ammonia in an autoclave at 200° for 24 hours, and by the reaction of 1,3,5-triazine and hydrazine monohydrochloride. ... 

While the usual eonsequence of hydration of enamines is eleavage to a secondary amine and an aldehyde or ketone, numerous cases of stable carbinolamines are known (102), particularly in examples derived from cyclic enamines. The selective terminal hydration (505) of a cross-conjugated dienamine-vinylogous amide is an interesting example which gives an indication of the increased stabilization of the vinylogous amide as compared to simple enamines, which is also seen in the decreased nucleophilicity of the conjugated amino olefin-carbonyl system. 

Heterocyclic structures analogous to the intermediate complex result from azinium derivatives and amines, hydroxide or alkoxides, or Grignard reagents from quinazoline and orgahometallics, cyanide, bisulfite, etc. from various heterocycles with amide ion, metal hydrides,or lithium alkyls from A-acylazinium compounds and cyanide ion (Reissert compounds) many other examples are known. Factors favorable to nucleophilic addition rather than substitution reactions have been discussed by Albert, who has studied examples of easy covalent hydration of heterocycles. 

Cu(II) and these complexes may by an octahederal structure due to formation of coordination bonds between the amide group and water of hydration with Cu(II) (2) the polymer chains form hydrogen bonds with... 

Water-soluble pAM neutral polymer interacts with ions of the solution through the complex formation between amide groups and hydrated ions. 

A suspension of sodium amide2 (0.1 mole) in liquid ammonia is prepared in a 500-ml. three-necked, round-bottomed flask fitted with a West condenser, a ball and socket glass mechanical stirrer (Note 1), and a dropping funnel. In the preparation of this reagent a small piece of clean sodium metal is added to 350 ml. of commercial anhydrous liquid ammonia. After the appearance of a blue color, a few crystals of hydrated ferric nitrate are added, whereupon the blue color is discharged. The remainder of the 2.3 g. (0.1 mole) of sodium (Note 2) is then rapidly added as small pieces. After all the sodium has been converted to sodium amide (Note 3), a solution of 16.4 g. (0.1 mole) of ethyl phenyl-acetate (Note 4) in 35 ml. of anhydrous ethyl ether is added dropwise over a 2-minute period, and the mixture is stirred for 20 minutes. To the dark green suspension is added over an 8-minute period a solution of 18.5 g. (0.1 mole) of (2-bromo-... 

Calcium-binding proteins, 6, 564, 572, 596 intestinal, 6, 576 structure, 6, 573 Calcium carbonate calcium deposition as, 6, 597 Calcium complexes acetylacetone, 2, 372 amides, 2,164 amino acids, 3, 33 arsine oxides, 3, 9 biology, 6, 549 bipyridyl, 3, 13 crown ethers, 3, 39 dimethylphthalate, 3, 16 enzyme stabilization, 6, 549 hydrates, 3, 7 ionophores, 3, 66 malonic acid, 2, 444 peptides, 3, 33 phosphines, 3, 9 phthalocyanines, 2,863 porphyrins, 2, 820 proteins, 2, 770 pyridine oxide, 3,9 Schiff bases, 3, 29 urea, 3, 9... 

Als cinziges unsubstituiertes Carbonsaure-amid konnte Heptafluor-butansaure-amid mit Lithiuma-lanat zum Heptafluor-butanal-Hydrat (s. a. S. 108, 146f.) reduziert werden2. 

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