1,4-Elimination of water

Here the polymer grows by successive esterification with elimination of water and no termination step. 

Claisen reaction Condensation of an aldehyde with another aldehyde or a ketone in the presence of sodium hydroxide with the elimination of water. Thus benzaldehyde and methanal give cinnamic aldehyde, PhCH CH-CHO. 

Most biological catalysts are enzymes, i.e., proteins, which are macromolecules (polypeptides) fonned by biopolymerization of amino acids (with elimination of water) some enzymes are huge, with hundreds of monomer units. The 20 amino acid monomers occurring in nature. 

Aldehydes undergo condensation with primary amines with the elimination of water to give compounds known as SchifF s Bases, which can also be used to characterise aldehydes. Benzaldehyde for example condenses readily with... 

This Condensation should not be confused with the Claisen Reaction, which is the condensation of an aldehyde with (i) another aldehyde, or (ii) a ketone, under the influence of sodium hydroxide, and with the elimination of water. For details, see Diben zal-acetone. p, 231. 

Many chloroplatinates separate from aqueous solution with water of crystallisation. If this is suspected, the chloroplatinate should be dried to constant weight in the oven before analysis, to ensure elimination of water of crystallisation. Aniline, p-toluidine and pyridine all give anhydrous chloroplatinates, and can be conveniently used in the above determination no attempt should be made to recryrtallise their chloroplatinates. 

It has been tentatively suggested that one mechanism underlies the Willgerodt reaction and the Kindler modification of it. A labile intermediate is first formed which has a carbon—carbon bond in the side chain. The scheme is indicated below it postulates a series of steps involving the addition of ammonia or amine (R = H or alkyl), elimination of water, re addition and eUmination of ammonia or amine until the unsaturation appears at the end of the chain then an irreversible oxidation between sulphur and the nitrogen compound may occur to produce a thioamide. 

The condensation of the monomers with the elimination of water and the formation of a polyimine [XII] occurs at temperatures around 250°C. 

Polyethers are also products of commercial importance. Ethers can be formed by thermal dehydration, as shown for the formation of dipropylene glycol from propylene glycol. CycHc ethers can form by elimination of water from di- or tripropylene glycol. 

Manufacture. Malononitiile can be produced batchwise by elimination of water from cyano acetamide [107-91-5] with phosphorous... 

Etherification. Ethers of poly(vinyl alcohol) are easily formed. Insoluble internal ethers are formed by the elimination of water, a reaction cataly2ed by mineral acids and alkaU. 

Alcohols react with boric acid with elimination of water to form borate esters, B(OR)3. A wide variety of borate salts and complexes have been prepared by the reaction of boric acid and inorganic bases, amines, and heavy-metal cations or oxyanions (44,45). Fusion with metal oxides yields... 

Manufacture. Cinnamaldehyde is routinely produced by the base-cataly2ed aldol addition of ben2aldehyde /7(9(9-with acetaldehyde [75-07-0], a procedure which was first estabUshed in the nineteenth century (31). Formation of the (H)-isomer is favored by the transition-state geometry associated with the elimination of water from the intermediate. The commercial process is carried out in the presence of a dilute sodium hydroxide solution (ca 0.5—2.0%) with at least two equivalents of ben2aldehyde and slow addition of the acetaldehyde over the reaction period (32). 

Protonation of the hydroxy group followed by the elimination of water generates the resonance-stabilized diazonium salt. 

Esters are most commonly prepared by the reaction of a carboxyHc acid and an alcohol with the elimination of water. Esters are also formed by a number of other reactions utilizing acid anhydrides, acid chlorides, amides, nitriles, unsaturated hydrocarbons, ethers, aldehydes, ketones, alcohols, and esters (via ester interchange). Detailed reviews of esterification are given in References 1—9. 

Provision of efficient drift eliminators of water cooling towers consideration of replacement by air cooling systems. Thermal insulation to protect personnel from contact with hot or cold surfaces prevention of water supply disruption by freezing. 

Maintenance may be reduced due to elimination of water fouling characteristics which could require frequent cleaning of water cooled heat exchangers... 

Elimination of water with the aid of sulfunc acid [9 14] and formation of the corresponding monoterpene hydrocarbons... 

Aminodiphenyl reacts with carbonyl compounds to form colored or fluorescent Schiff s bases with the elimination of water ... 

Dinitrophenylhydrazine reacts with carbonyl groups with the elimination of water to yield hydrazones (I) and with aldoses or ketoses to yield colored osazones (II). 

In Robinson s now well-known suggestions, regarding the processes by which alkaloids may be produced in plants, two main reactions are used j the aldol condensation and the similar condensation of carbinol-amines, resulting from the combination of an aldehyde or ketone with ammonia or an amine, and containing the group. C(OH). N., with substances in which the group, CH. CO. is present. By these reactions it is possible to form the alkaloid skeleton, and the further necessary changes postulated include oxidations or reductions and elimination of water for the formation of an aromatic nucleus or of an ethylene derivative. 

The elimination of water from a fluorinated compound generally follows a reaction path similar to that of its nonfluorinated counterpart, although the presence of the highly electronegative fluorine atoms may have unexpected effects Various monofluoro alcohols can be dehydrated via their tosyl esters at 75 C by using potassium rert-butoxide [80] (equation 50)... 

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