Vinyl glyoxal

As an illustration of the importance of selective dehydration, the reaction of tetrose sugars in alcoholic media with soluble Sn halides has recently been reported [100]. This presents a homogeneous catalytic system, which delivers both Brpnsted (as HCl) and Lewis (as Sn " or Sn" " ) acids. The final products of this conversion were useful a-hydroxy-acids, such as vinyl glycolic acid as discussed in detail in Chap. 3 of this volume (Dusselier et al.). The first step in the reaction path involves a double dehydration leading to the proposed intermediate vinyl glyoxal, as shown being derived from the tetrose in Fig. 12. The mechanism of the dehydration of tetroses is shown in more detail in steps 1 and 2 in Fig. 13 (tentatively catalyzed by a Sn salt). 

Poly(vinyl alcohol) is readily cross-linked with low molecular weight dialdehydes such as glutaraldehyde or glyoxal (163). Alkanol sulfonic acid and poly(vinyl alcohol) yield a sulfonic acid-modified product (164). 

Controlling fluid loss loss is particularly important in the case of the expensive high density brine completion fluids. While copolymers and terpolymers of vinyl monomers such as sodium poly(2-acrylamido-2-methylpropanesulfonate-co-N,N-dimethylacrylamide-coacrylic acid) has been used (H)), hydroxyethyl cellulose is the most commonly used fluid loss additive (11). It is difficult to get most polymers to hydrate in these brines (which may contain less than 50% wt. water). The treatment of HEC particle surfaces with aldehydes such as glyoxal can delay hydration until the HEC particles are well dispersed (12). Slurries in low viscosity oils (13) and alcohols have been used to disperse HEC particles prior to their addition to high density brines. This and the use of hot brines has been found to aid HEC dissolution. Wetting agents such as sulfosuccinate diesters have been found to result in increased permeability in cores invaded by high density brines (14). 

Figure 5.6 Alcohols, aldehydes, ketones and acids 15, ethylene glycol 16, vinyl alcohol 17, acetaldehyde 18, formaldehyde 19, glyoxal 20, propionaldehyde 21, propionaldehyde 22, acetone 23, ketene 24, formic acid 25, acetic acid 26, methyl formate. (Reproduced from Guillemin et at. 2004 by permission of Elsevier)...

Mikami and co-workers16-19 have done extensive work for developing catalysts for the asymmetric carbonyl-ene reaction. Excellent enantioselectivites are accessible with the binol-titanium catalyst 17 (Equation (10)) for the condensation of 2-methyl butadiene (R1 = vinyl) and glyoxalates (binol = l,T-binaphthalene-2,2 -diol).16 The products were further manipulated toward the total synthesis of (i )-(-)-ipsdienol. The oxo-titanium species 18 also provides excellent enantioselectivity in the coupling of a-methyl styrene with methyl glyoxalate.17 Reasonable yields and good enantioselectivites are also obtained when the catalyst 19 is formed in situ from titanium isopropoxide and the binol and biphenol derivatives.18... 

Reagents vinyl acetate, ethyl glyoxalate, 60 °C, 14h bovine serum albumin (BSA), thymine, TMSOTf, MeCN, A, 1 h 3.7% HCl in EtOH, room temperature (rt), 3 h. 

Oxidation of methyl ketone guanylhydrazones (686) with selenium dioxide affords the corresponding monosubstituted glyoxal derivatives (687) which cyclize to the 5-unsubstituted 3-amino-1,2,4-triazines (473) (78HC(33)189, p.360). We have already noted the cyclization of bis(alkylidene)- or bis(arylidene)-acetone guanylhydrazones (475) in the synthesis of 6-(vinyl-substituted) 3-amino-1,2,4-triazines (477) (Section 2.19.4.1.1). 

Reacts violently with many chemicals, including acetic acid, acetic anhydride, acrolein, acrylic acid, allyl chloride, carbon disulfide, chloride glyoxal, and vinyl acetate.4 Acids. Polymerizes violently.5... 

Heterocycles Acetylacetone. N-Aminophthalimide. Boron trichloride. Dichloro-formoxime. Oicyanodiamide. Dicyclohexylcarbodiimide. Dietboxymethyl acetate. Diethyl oxalate. Diketene. Dimethylformaniide diethylacetal. Diphenyldiazomethene. Ethyl ethoxy-methylenecyanoacetate. Formaldehyde. Formamide. Formamidine acetate. Formic acid. Glyoxal. Hydrazine. Hydrazoic acid. Hydroxylamine. Hydroxylamine-O-sulfonic acid. Methyl vinyl ketone. o-Phenylenediamine. Phenylhydrazine. Phosphorus pentasullide. Piperidine. Folyphosphoric acid. Potassium diazomethanedisulfonate. Sodium ethoxide. Sodium nitrite. Sodium thiocyanate. Tetracyanoethylene. Thiosemicarbozide. Thiourea. Triethyl orthoformate. Tris-formaminomethane. Trityl perchlorate. Urea. Vinyl triphenyl-phosphonium bromide. 

These compounds, exemplified by acrolein, crotonaldehyde, and methyl vinyl ketone, are known to react with ozone and with OH radicals. Photolysis and N03 radical reaction are of minor importance. Under atmospheric conditions the 03 reactions are also of minor significance (Atkinson and Carter, 1984), leaving the OH radical reaction as the major loss process. For the aldehydes, OH radical reaction can proceed via two reaction pathways OH radical addition to the double bond and H-atom abstraction from the -CHO group (Atkinson, 1989). For crotonaldehyde, for example, the OH reaction mechanism is given in Fig. 3. As can be noted from Fig. 3, these a,/3-unsaturated aldehydes are expected to ultimately give rise to a-dicarbonyls such as glyoxal and methylglyoxal. For the a,/3-unsaturated ketones such as methyl vinyl ketone, the major... 

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