Amines and amides

The distinctive tangy taste of sourdough bread results from the work of the yeast and lactobacteria that also produce the carbon dioxide that makes the bread rise. Acetic acid and lactic acid, both carboxylic acids, are produced during the fermentation, giving sourdough bread its sour taste. 

The odors of most fruits and many perfumes are due to molecules that contain the ester functional group. 

Formic acid and acetic acid are the two most important carboxylic acids. Formic acid is a source of irritation in the bites of ants and other insects or in the scratch of nettles. A liquid with a sharp, irritating odor, formic acid is used in manufacturing esters, salts, and plastics. Acetic acid is present in a concentration of about 5% in vinegar and is responsible for its odor and taste. Acetic acid is among the least expensive organic acids, and is therefore a raw material in many commercial processes that require a carboxylic acid. Sodium acetate is one of several common salts of carboxylic acids. It is used to control the acidity of chemical processes and in preparing soaps and pharmaceutical agents. 

Ethyl acetate and butyl acetate are two of the relatively few esters produced in large quantity. Both are used as solvents, particularly in manufacturing lacquers. Other esters are used in the plastics industry, and some find application in medicinal fields. Esters are responsible for the odors of most fruits and flowers, leading to their use in the food and perfume industries. 

24 Identify the structural formulas of the functional groups that distinguish amines and amides. 

The amines resemble ammonia in chemical properties. Thus they unite with acids and form well characterized salts methyl-amine, for example, combines with hydrochloric acid and forms a salt which is called methyl-ammonium chloride — 

The salt is sometimes called methylamine hydrochloride, and its formula is written CH3NH2.HCI. The replacement of hydrogen in ammonium hydroxide by positive alkyl groups yields compounds which react with water and form bases much stronger than ammonium hydroxide. The accumulation of positive radicals in the quarternary ammonium bases results in the production of marked basic properties in these compounds. Tetra-methyl-ammonium hydroxide shows about as strong basic properties as potassium hydroxide. 

Amines which are derived from bivalent radicals are also 

The compounds formed by the replacement of hydrogen atoms by acyl radicals are called amides. Acetamide, CH3CO.NH2, diacetamide, (CH3CO)2NH, and triacetamide (CH3C0)3N, are examples of the three classes of compounds which exist. Of the amides only those which contain one acyl group will be considered here. 

The amides which contain one acyl group may be considered as substitution-products of acids formed by the replacement of the hydroxyl by the NH2 group. As this group occurs in many organic compounds, it has been given the name amido. When it is in combination with a positive radical and shows, therefore, basic properties it is called the amino group to emphasize the relation of the compound in which it is present to the amines. 

Several systems are used for naming amines. For simple amines, the common names are often used. In the common name, the alkyl groups bonded to the nitrogen atom are listed in alphabetical order. The prefixes di and tri are used to indicate two and three identical substituents. 

FIGURE 17.8 Amines have one or more carbon atoms bonded to the N atom. 

Q How many carbon atoms are bonded to the nitrogen atom in dimethylamine  

The aromatic amines use the name aniline, which is approved by lUPAC. 

Aniline is used to make many dyes, which give color to wool, cotton, and silk fibers, as well as blue jeans. It is also used to make the polymer polyurethane and in the synthesis of the pain reliever acetaminophen. 

Basic properties of a solution of methylamine.—Test the distillate obtained in the experiment just described with pink litmus paper. 

Isolation of Lecithin from Egg-yolk (section 217).— Grind the yolk of one hard-boiled egg with 50 cc. of ether. Filter and wash the solid residue twice with 10 cc. of ether. Evaporate off the ether on the steam-bath, or distil it off from a small flask. Extract the residue twice with hot alcohol, using 10 cc. each time. Pour off the alcohol from the heavy oil through a small filter. Evaporate off the alcohol, dissolve the residue in 10 cc. of cold ether, and add 10 cc. of acetone. Stir until the particles of the precipitated lecithin adhere together and form a ball. Place the latter on a filter-paper. Describe its properties. Boil about one-fourth of the lecithin with about 10 cc. of a 10 per cent solution of sodium hydroxide. Note the odor of the gas evolved. What is it Cool the solution. Is there any evidence of the formation of a soap Filter, dissolve the precipitate in warm water and add dilute hydrochloric acid to the solution. What is precipitated Test a part of the lecithin for nitrogen and for phosphorus ( 58, 59, 61, page 39). 

—Ether dissolves hum egg-yolk, in addition to lecithin, some fat and protein. The protein and a part of the fat are removed by extracting the residue from ether with alcohol. The lecithin is finally separated by adding acetone to an etheral solution of the lecithin and fat. The latter is soluble in acetone while the lecithin is insoluble. 

Preparation of Acetamide from Ethyl Acetate (SECTION 221).—Mix in a 250-cc. distilling flask 50 grams of ethyl acetate and 100 cc. of a concentrated aqueous solution of ammonia 

Acetamide melts at 82°, and boils at 222°. The yield obtained in the preparation should be about 65 per cent of the theoretical. 

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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. 

Some of the physical properties of fatty acid nitriles are Hsted in Table 14 (see also Carboxylic acids). Eatty acid nitriles are produced as intermediates for a large variety of amines and amides. Estimated U.S. production capacity (1980) was >140, 000 t/yr. Eatty acid nitriles are produced from the corresponding acids by a catalytic reaction with ammonia in the Hquid phase. They have Httie use other than as intermediates but could have some utility as surfactants (qv), mst inhibitors, and plastici2ers (qv). 

Traces of formaldehyde, present in neat end-capped polymer or produced by processing polymer under abusive conditions, detract from polymer stabihty. Commercial resins typically contain formaldehyde scavengers. Nitrogen compounds, especially amines and amides, epoxies, and polyhydroxy compounds, are particularly efficacious scavengers. 

Catalytic vinylation has been appHed to a wide range of alcohols, phenols, thiols, carboxyUc acids, and certain amines and amides. Vinyl acetate is no longer prepared this way in the United States, although some minor vinyl esters such as stearates may still be prepared this way. However, the manufacture of vinyl-pyrrohdinone and vinyl ethers still depends on acetylene. 

Reactions with Amines and Amides. Hydroxybenzaldehydes undergo the normal reactions with aUphatic and aromatic primary amines to form imines and Schiff bases reaction with hydroxylamine gives an oxime, reaction with hydrazines gives hydrazones, and reactions with semicarbazide give semicarbazones. The reaction of 4-hydroxybenzaldehyde with hydroxylamine hydrochloride is a convenient method for the preparation of 4-cyanophenol (52,53). 

The primary products used are fatty acids with 12—18 carboa atoms and fatty alcohols, or esters of fatty acids such as the glycerides of rapeseed and lard oil (18). Eatty acid amines and amides are used ia metal working, particularly ia emulsions (18). 

Significant quantities of amine and amide esters are formed by side reactions (9). In addition, with dialkanolamines, amide diesters, morpholines, and piperazines can be obtained, depending on the starting material. Reaction of dialkanolamines with fatty acids in a 2 1 ratio, at 140—160°C, produces a second major type of alkanolamide. These products, in contrast to the 1 1 alkanolamides, are water soluble they are complex mixtures of AJ-alkanolamides, amine esters, and diesters, and still contain a considerable amount of unreacted dialkanolamine, accounting for the water solubiUty of the product. Both the 1 1 and the 2 1 alkanolamides are of commercial importance in detergents. 

The second type of diethanolamide is the 1 1 or superamide which contains components of the reaction of one mole fatty acid and one mole diethanolamine. A typical superamide composition is >90% diethanolamide, 7% unreacted diethanolamine, and 2.5% amine and amide ester. 

A number of people must be thanked for their contributions and help in completing this project. I am grateful to Gordon Bundy, who loaned me this card file, which provided many references that the computer failed to find, and to Bob Williams, Spencer Knapp, and Tohm Fukuyama for many references on amine and amide protection. I thank Theo Greene who checked and rechecked the manuscript for spelling and consistency and for the herculean task of checking all the references to make sure my 3s and 8s and 7s and 9s were not interchanged, all w iihout... 

Hydrazides of vicinal acetylene-substituted derivatives of benzoic and azole carboxylic acids are important intermediate compounds because they can be used for cyclization via both a- and /3-carbon atoms of a multiple bond involving both amine and amide nitrogen atoms (Scheme 131). Besides, the hydrazides of aromatic and heteroaromatic acids are convenient substrates for testing the proposed easy formation of a five-membered ring condensed with a benzene nucleus and the six-membered one condensed with five-membered azoles. 

In contrast with amines, amides (RCONH ) are nonbasic. Amides don t undergo substantial protonation by aqueous acids, and they are poor nucleophiles. The main reason for this difference in basicity between amines and amides is that an amide is stabilized by delocalization of the nitrogen lone-pair electrons through orbital overlap with the carbonyl group. In resonance terms, amides are more stable and less reactive than amines because they are hybrids of two resonance forms. This amide resonance stabilization is lost when the nitrogen atom is protonated, so protonation is disfavored. Electrostatic potential maps show clearly the decreased electron density on the amide nitrogen. 

Over the past years, interest in the preparation of chiral amines and amides by enzymatic ammonolysis or aminolysis reactions [4] has greatly increased for academic and industrial sectors. The role that the enzymatic acylation of amines or ammonia plays for the preparation of some pharmaceuticals is noteworthy [5]. 

Although the aminolysis of esters to amides is auseful synthetic operation, usually it presents some disadvantages in terms of drastic reaction conditions, long reaction times or strong alkali metal as catalyst, which are usually not compatible with other functional groups in the molecule [6]. For this reason, enzymatic aminolysis of carboxylic acid derivatives offers a clean and ecological way for the preparation of different kind of amines and amides in a regio-, chemo-, and enantioselective manner. 

Amines and amides can be N-nitrated with nitric acid, or and... 

Primary and secondary amines and amides are first chlorinated at nitrogen by the chlorine released by the gradually decomposing calcium hypochlorite. Excess chlorine gas is then selectively reduced in the TLC layer by gaseous formaldehyde. The reactive chloramines produced in the chromatogram zones then oxidize iodide to iodine, which reacts with the starch to yield an intense blue iodine-starch inclusion complex. 

In the same paper the authors list the responses of a number of amines and amides towards permanganate and record the effect of freezing the medium upon the oxidation of benzylamine. 

In classical organic chemistry, nltrosamlnes were considered only as the reaction products of secondary amines with an acidified solution of a nitrite salt or ester. Today, it is recognized that nitrosamines can be produced from primary, secondary, and tertiary amines, and nltrosamides from secondary amides. Douglass et al. (34) have published a good review of nitrosamine formation. For the purposes of this presentation, it will suffice to say that amine and amide precursors for nitrosation reactions to form N-nitroso compounds are indeed ubiquitous in our food supply, environment, and par-... 

Various additives in PE (Santonox, Nonox DPPD, Neozone A, Ionol and Agerite White) were determined by conventional TLC [507]. Other additives in PE, studied by means of TLC, were Tinuvin P 120/326/327/770, Cyasorb UV531, Anti UV P (2-hydroxy-4-n-octyloxybenzophenone), Irganox 1076, Sanduvor EPU, AO-4 and Dastib 242/263 [508], TLC has also been used in the analysis of additives in polyurethanes [509,510] as well as of slip additives (ethoxylated amines and amides) in HDPE extracts... 

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