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Of glyoxal

Ozonation of Aromatics. Aromatic ring unsaturation is attacked much slower than olefinic double bonds, but behaves as if the double bonds in the classical Kekule stmctures really do exist. Thus, benzene yields three moles of glyoxal, which can be oxidized further to glyoxyUc acid and then to oxahc acid. Substituted aromatics give mixtures of aUphatic acids. Ring substituents such as amino, nitro, and sulfonate are cleaved during ozonation. [Pg.494]

A less important glyoxal resin is tetramenthylolglycolutil [5395-50-6] (tetramethylolacetylenediurea) produced by the reaction of 1 mol of glyoxal with 2 mol of urea, and 4 mol of formaldehyde. [Pg.330]

This resin was most popular in Europe, partiy because of its lower requirements of glyoxal. However, because of increased availabiHty and lower glyoxal costs plus certain appHcation weaknesses, it has been generally replaced by DMDHEU. [Pg.330]

Dihydroxyethyleneurea (DHEU) (6) is also a cross-linker, but is extremely vulnerable to hydrolysis in an alkaline home laundering. Another approach toward formaldehyde-free agents has been the use of glyoxal in the bridging group between cycHc DHEU and related ring systems (108). [Pg.447]

Textiles. Citric acid acts as a buffer in the manufacture of glyoxal resins which are used to give textiles a high quaUty durable-press finish (see Amino resins). It has been reported to increase the soil-release property of cotton with wrinkle-resistant finishes and is used as a buffer, a chelating agent, and a non-volatile acid to adjust pH in disperse dying operations (182—193). [Pg.186]

Tetrakis (4-hydroxyphenyl)ethane is prepared by reaction of glyoxal with phenol in the presence of HCl. The tetraglycidyl ether [27043-37-4] (4), mp ca 80°C, possesses a theoretical epoxide functionaUty of four with an epoxy equivalent weight of 185—208 (4). [Pg.364]

Muconic acid has been obtained in a variety of ways. The procedures that seem most important from a preparative point of view are by treatment of ethyl o ,5-dibromoadipate with alcoholic potassium hydroxide, by condensation of glyoxal (as the sodium bisulfite addition product) with malonic acid, by heating ethyl l-acetoxy-l,4-dihydromuconate (obtained by condensing ethyl oxalate and ethyl crotonate, acetylating, and reducing),and by oxidation of phenol with peracetic acid. ... [Pg.60]

Most of the compounds in this class have been prepared from preexisting crown ether units. By far, the most common approach is to use a benzo-substituted crown and an electrophilic condensation polymerization. A patent issued to Takekoshi, Scotia and Webb (General Electric) in 1974 which covered the formation of glyoxal and chloral type copolymers with dibenzo-18-crown-6. The latter were prepared by stirring the crown with an equivalent of chloral in chloroform solution. Boron trifluoride was catalyst in this reaction. The polymer which resulted was obtained in about 95% yield. The reaction is illustrated in Eq. (6.22). [Pg.278]

Treatment of glyoxal with sulfur tetrafluoride in the presence of sodium fluoride results iii the formation of difluoroethylene glycol orthosulfite [174] (equation 89) Similarly, perfluonnated 1,2-diketones react with sulfur tetrafluonde to give tetraoxyspirosulfuranes as the only products Thus, perfluorobiacetyl gives a ciystalhne product, perfluorobutylene glycol 2,3 orthosulfite [175] (equation 89)... [Pg.239]

Chiral cyclic /V,D-acetals of glyoxal and their use for preparation of a-amino acids 98SL449. [Pg.211]

Compounds which contain two oxazirane rings are obtainable from Schiff s bases of glyoxal or terephthalic dialdehyde, e.g. (6). A bifunctional oxazirane is also obtained from ethylene diamine and cyclohexanone (7)d ... [Pg.87]

The reaction of ozone with an aromatic compound is considerably slower than the reaction with an alkene. Complete ozonolysis of one mole of benzene with workup under non-oxidative conditions will yield three moles of glyoxal. The selective ozonolysis of particular bonds in appropriate aromatic compounds is used in organic synthesis, for example in the synthesis of a substituted biphenyl 8 from phenanthrene 7 ... [Pg.219]

Condensadon of glyoxalic acid, nitroalkanes, and amines provides a simple method for fi-nitro-ct-airino acids fEq 4 116 ... [Pg.107]

The monohydrazone of glyoxal is stabilized by resonance. Hence, it is quite difficult to achieve acetalization. [Pg.712]

Table 4.9 Diels-Alder reactions of glyoxal derivatives promoted by microwaves under different experimental conditions... Table 4.9 Diels-Alder reactions of glyoxal derivatives promoted by microwaves under different experimental conditions...
Symmetrical N, N -disubstituted imidazolium salts are usually obtained by addition of paraformaldehyde on a bis-imine of glyoxal under acidic conditions. A one-pot procedure has been developed. Several enantiomerically pure amines were used to prepare the corresponding symmetrical salts 6 (Scheme 4) [12,13]. [Pg.197]

The degradation of 1,2,3-trichloropropane by Agrobacterium radiobacter strain ADI involves hydrolysis of an intermediate epichlorohydrin (3-chloroprop-l-ene) to the diol (Bosma et al. 1999, 2002). An enzyme from this strain has been modified from the use of epichlorohydrin that is its normal substrate to accept dy-l,2-dichloroethene with the release of chloride and the presumptive formation of glyoxal (Rui et al. 2004). [Pg.365]

H). On the other hand, the synthesis of unsymmetricaUy iV,iV -substituted congeners is less straightforward as a functionalised imidazole has to be isolated prior to alkylation or arylation. Two main methods are available for imidazole functionaU-sation deprotonation with metalUc Na or K leading to an imidazoUde (I) followed by reaction with RX or reaction of glyoxal with a primary amine, an ammonium salt and formaldehyde (J). Al-functionalised imidazole can then be alkylated or... [Pg.6]

There also have been accidents that seemed to be the result of the mere contact of glyoxal with air. [Pg.307]

Ozonolysis was once used to locate the position of a double bond (or bonds) in unsaturated compounds of unknown structure—largely because of the ease of characterisation of the carbonyl products— but has now been superseded by physical methods, e.g. n.m.r. spectroscopy, which are easier and quicker. Benzene forms a triozonide which decomposes to yield three molecules of glyoxal, OHC—CHO the sole reaction of benzene that suggests it may contain three real double bonds in a Kekule structure Alkynes also undergo ozonolysis, but at a much slower rate than alkenes. [Pg.194]

Alternatively, this may be done in a flask, which is shaken by hand frequently to prevent formation of a solid cake. The use of a stirrer results in a granular product. The mother liquor retains about 7 g. of glyoxal bisulfite per liter. [Pg.94]

Isobe, K. and Nishise, H. (1994) Enzymic production of glyoxal from ethylene glycol using alcohol oxidase from methanol yeast. Bioscience Biotechnology and Biochemistry, 58 (1), 170-173. [Pg.165]

The use and reactions of glyoxal as a fixative have been reviewed extensively.3334 Glyoxal is the second smallest aldehyde, being like two formaldehyde molecules arranged back-to-back (Fig. 12.8, left). It too forms hydrates with water, the most common of which is 1,3-dioxolane (Fig. 12.8, right). [Pg.212]

Base-catalyzed Reactions of Glyoxal Monohydrazones with Active Methylene Compounds 276... [Pg.512]

Compound 642, obtained by condensation of glyoxal with benzotriazole and morpholine undergoes interesting [2+3] cyclocondensation with 2-aminopyridine to give imidazo[l,2- ]pyridine 643 (Equation 15) <2003JOC4935>. Similar derivatives of piperidine and pyrrolidine are also described. 2-Amino- and 6-aminopyrimidines react similarly to give imidazo[l,2- ]- and imidazoll - pyrimidines, respectively. [Pg.75]


See other pages where Of glyoxal is mentioned: [Pg.330]    [Pg.396]    [Pg.258]    [Pg.125]    [Pg.712]    [Pg.1523]    [Pg.133]    [Pg.312]    [Pg.363]    [Pg.131]    [Pg.172]    [Pg.173]    [Pg.157]    [Pg.353]    [Pg.120]    [Pg.121]    [Pg.212]    [Pg.333]    [Pg.48]    [Pg.68]    [Pg.79]    [Pg.80]   
See also in sourсe #XX -- [ Pg.32 ]




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