Condensation reaction ether formation

Condensation reaction (Section 15 7) Reaction m which two molecules combine to give a product accompanied by the expulsion of some small stable molecule (such as water) An example is acid catalyzed ether formation... 

The second step is the condensation reaction between the methylolphe-nols with the elimination of water and the formation of the polymer. Crosslinking occurs hy a reaction between the methylol groups and results in the formation of ether bridges. It occurs also by the reaction of the methylol groups and the aromatic ring, which forms methylene bridges. The formed polymer is a three-dimensional network thermoset ... 

Condensation reactions between two hydroxymethyl substituents eliminate water to form ether linkages (Fig. 7.23a) or eliminate both water and formaldehyde to form methylene linkages (Fig. 7.23b). Ether formation is favored under neutral or acidic conditions and up to 130°C above which formaldehyde departs and methylene linkages are generated. The methylene linkage formation reaction, which eliminates water and fortualdehyde, is more prevalent under basic conditions. Condensation reactions between hydroxymethyl groups and reactive... 

A condensation reaction joins two molecules and splits out a small molecule. The small molecule is usually water. The formation of a peptide bond is an example of a condensation reaction. The conditions necessary for a condensation reaction vary with the functional groups involved. In most cases, a catalyst will be present. The two most common catalysts are acids and enzymes. Two alcohols will condense to form an ether. A carboxylic acid condenses with an alcohol to form an ester. A carboxylic acid condenses with an amine to form an amide. 

Serine has been prepared by the Strecker method from glycol-aldehyde 1 and from ethoxyacetaldehyde,2 3 by the condensation of ethyl formate with ethyl hippurate followed by reduction and hydrolysis,4 5 from the reaction product of chloromethyl ether with ethyl sodium phthalimidomalonate,6 and by amination of a-bromo-/3-methoxypropionic acid with subsequent demethyla-tion.7... 

Both reactions act to reduce hydrogen bonding within the coal structure which may have a direct positive impact on liquefaction reactivity. More indirectly, these reactions lower the concentration of OH species in coal-derived products and hence, reduce the extent of retrogressive condensation via ether bridge formation. Reducing production of THF-insoluble condensation products increases the net THF-soluble coal conversion observed during the liquefaction experiment. None of the spectra from coals pretreated with alkyl alcohols and HCl showed any significant evidence of alkylation at carbon sites in the coal. 

Georgiev et al. [82] have described the preparation of novel adamantine-spiro-heterocyclic (3-lactams 34, 35, and 40. Grignard reaction of 2-adamantanone 31 with benzylmagnesium halide provided the compound 32, which on further dehydration afforded corresponding analogs 33. Condensation reaction of compound 33 with chlorosulfonyl isocyanate in ether afforded spiro-(3-lactams 34 and cycloaddition with chlorosulfonyl isocyanate resulted in the formation of spiro product 35 (Scheme 10). 

Ethers are formed from condensation reactions (result in the formation of water) between two alcohols. The main function of ethers is their use as solvents. Ethers are named by placing the names of the two R groups (R and R ) before the word ether. The R groups should be listed in alphabetical order if they are two different groups. 

The rate of this reaction is about ten times smaller than that of Eq. (I) and under typical cure conditions it becomes noticeable only after the end of the main process. Scheme (II) changes the structure of networks by the formation of additional crosslinks of the ether type. This makes the total connectivity of the network higher. This structural change influences some properties of polymers in the glassy and rubbery state (see Sects. 4 and 5), but it is really pronounced in nonstoichiometric systems with an excess (P < 0.8) of epoxy components 19,22). Crosslinks of the ether type may principally appear in polymers due to a condensation reaction between OH groups. Under our conditions this process normally does not take place. 

However, over Ni-kieselguhr in the absence of solvent or in ether and methylcyclo-hexane 32-33% of a diester, ethyl 3-(3 -hydroxybutyryloxy)butyrate (8), was produced along with 68-67% of ethyl 3-hydroxybutyrate and small quantities of dehydroacetic acid, and over copper-chromium oxide 16% of the diester and 7% of dehydroacetic acid were formed in the absence of solvent. It was suggested that the diester is formed through the hydrogenation of the intermediate 9, which results from 2 mol of acetoacetic ester with elimination of 1 mol of ethanol and that the condensation reaction is reversible (Scheme 5.6). Hence, the formation of the diester is depressed in the hydrogenation in ethanol.121 The reaction pathway in Scheme 5.6 has... 

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