Aldehydes chloroacetaldehyde

Other aldehydes which have been used in the reaction are pro-panal, butanal, glycolaldehyde, 3-hydroxybutanal, and a number of phenylacetaldehydeand benzaldehyde derivatives. Whereas condensation of tryptophan with acetaldehyde takes place even at room temperature and pH 6.7, the reactions with chloral, chloroacetaldehyde, and crotonaldehyde fail entirely. 

A cross-coupling reaction of aldehydes with a-diketones proceeded in the presence of water to give the corresponding adducts in moderate to good yield. It is possible to use the substrates such as phenyl-glyoxal monohydrate, aqueous methylglyoxal, formalin, and aqueous a-chloroacetaldehyde for this reaction.330... 

Chemical/Physical. Products of hydrolysis include chloroacetaldehyde, 1,1-dichloroethylene, and HCl. The aldehyde is subject to hydrolysis forming hydroxyacetaldehyde and HCl (Kollig, 1993). The reported half-life for this reaction at 20 °C is 170 yr (Vogel et al., 1987). Under alkaline conditions, 1,1,2-trichloroethane hydrolyzed to 1,2-dichloroethylene. The reported hydrolysis half-life in water at 25 °C and pH 7 is 139.2 yr (Sata and Nakajima, 1979). 

Aldehydes. The aldehydes studied in this program include acetaldehyde, chloroacetaldehyde, formaldehyde, furfural, crotonalde-hyde, and acrolein. Because of the instability of the aldehydes, they are best collected by derivatizing during sample collection. 

When 3-mercaptocyclohexanone condenses with dichloroacet-aldehyde or chloroacetaldehyde in the presence of a catalytic quantity of acid (e.g., p-toluenesulfonic acid), simultaneous cyclization occurs to give 4,5,6,7-tetrahydrobenzo[6]thiophen-4-one (see Section VI, B, 4) and 2,4,5,6,7,7a-hexahydrobenzo[6]thiophen-4-one (see Section... 

A]thiophene, and with polymeric chloroacetaldehyde, it leads to 5-ethylthieno[2,3-A]thiophene-2-aldehyde, characterized as its 2,4-dinitro-phenylhydrazone. 

For aldehyde, LUMO decreases as the number of chlorines increases. The dataset is 2,2,3-trichlorobutanal 2-chloropropanal chloroacetaldehyde and dichloroacetaldehyde. LUMO represents 90.49% of the variance in the linear regression equation therefore, the probability of getting a correlation of -0.9513 for a sample size of four is between 2 and 5% (see Figure 5.20). 

Dialkylzinc initiates homo- and copolymerization of aldehydes such as acetaldehyde 151, 234, 310, 487, 533), formaldehyde 310, 495), butyraldehyde 468), glutardehyde 386), cyanopropionaldehyde 479), chloroacetaldehyde 233, 234, 324, 325, 412, 495, 533), and dichloro-acetaldehyde 325). Aluminum triisopropoxide 485) and phosphorus compounds 339) were proposed as additives for the polymerizations. Polymerization of optically active aldehydes was also reported ). 

In both processes the aqueous crude aldehyde is concentrated and byproducts are removed in a two-step distillation. Both processes give 94% yields of aldehyde, along with small amounts of 2-chloroethanol, ethyl chloride, acetic acid, chloroacetaldehydes and acetaldehyde condensation products. The Wack-er-Hoechst process currently accounts for 85% of the worldwide production capacity for acetaldehyde. 

The importance of aqueous reactions is now generally recognized, and development of carbon-carbon bond-forming reactions that can be performed in aqueous media is now one of the most challenging topics in organic synthesis [59]. It has been found that Sc(OTf)3 was effective in aldol reactions of silyl enolates with aldehydes in aqueous media (water-THF Eq. 16) [4]. Reaction between aromatic and aliphatic aldehydes such as benzaldehyde and 3-phenylpropionaldehyde and silyl enolates have been performed successfully in aqueous solvents. In addition, direct treatment of aqueous solutions of water-soluble formaldehyde and chloroacetaldehyde with silyl enolates affords the corresponding aldol adducts in good yields. Water-sensitive silyl enolates could be used in aqueous solutions with Sc(OTf)3 as catalyst. 

Mannich-type reactions of aldehydes, amines, and vinyl ethers proceeded smoothly in the presence of a catalytic amount of Sc(OTf)3 in aqueous media (Eq. 20) [69]. Commercially available aqueous solutions of formaldehyde and chloroacetaldehyde were used directly and the corresponding /3-amino ketones were obtained in good yields. Phenylglyoxal monohydrate, methyl glyoxylate, an aliphatic aldehyde, and an a,/3-unsaturated aldehyde also worked well to give the corresponding /3-amino esters in high yields. 

Other aldehydes and related compounds have been reacted either alone or catalyzed with sulfuric acid, zinc chloride, magnesium chloride, ammonium chloride, or diammonium phosphate (94). Compounds such as l,3-bis(hydroxymethyl)-2-imidazolidone, glycol acetate, acrolein, chloroacetaldehyde, heptaldehyde, o- and p-chloro-benzaldehydes, furfural, p-hydroxybenzaldehyde, and m-nitrobenz-aldehyde all achieve the ASE by a bulking mechanism and not by low-level cross-linking. At weight gains of 15-25%, the highest ASE reported is 40%. 

The use of Ln(OTf)3 in the activation of aldehydes other than formaldehyde was also investigated [18], Several examples of the present aldol reaction of silyl enol ethers with aldehydes are listed in Table 14-1. In every case, the aldol adducts were obtained in high yields in the presence of a catalytic amount of Yb(OTf)3, Gd(OTf)3, or Lu(OTf)3 in aqueous media. Diastereoselectivities were generally good to moderate. One feature in the present reaction is that water-soluble aldehydes, for instance, acetaldehyde, acrolein, and chloroacetaldehyde, can be reacted with silyl enol ethers to afford the corresponding cross aldol adducts in high yields (entries 5-7). Some of these aldehydes are commercially supplied as water solutions and are appropriate for direct use. Phenylglyoxal monohydrate also worked well (entry 8). It is known that water often interferes with the aldol reactions of aldehydes with metal enolates and that, in the cases where such water... 

Incorporating aldehydic fiinctions in a polysaccharide can be accomplished by reacting the polysaccharide with chloroacetaldehyde dimethyl acetal. After unmasking of the acetal, the modified polysaccharide is reacted with proteins by reductive amination [33]. Since the initial reaction of chloroacetaldehyde dimethyl acetal with polysaccharide lacks site-specificity, this method suffers from randomness as well as multiplicity of the attachment site on the polysaccharide. 

Sc(OTf)3 can behave as a Lewis acid catalyst even in aqueous media. Sc(OTf)3 was stable in water and was effective in the aldol reactions of silyl enolates with aldehydes in aqueous media. The reactions of usual aromatic and aliphatic aldehydes such as benzaldehyde and 3-phenylpropionaldehyde with silyl enolates were carried out in both aqueous and organic solvents, and water-soluble formaldehyde and chloroacetaldehyde were directly treated as water solutions with silyl enolates to afford the aldol adducts in good yields. Moreover, the catalyst could be recovered almost quantitatively from the aqueous layer after the reaction was completed. The recovered catalyst was also effective in the second reaction, and the yield of the second run was comparable to that of the first run (Eq. 2). 

Benzofuroxan (5) reacts under mild conditions with an enamine or with an aldehyde or ketone in the presence of ammonia or an amine to form mono- or disubstituted quinoxaline dioxides (151). Dark red dihydro-quinoxaline dioxides (e.g., 152) may be formed when an enamine is used which does not possess an a-hydrogen atom for elimination.381 2-Amino-substituted quinoxaline dioxides have been produced using (a) an ynamine [providing tertiary amines (153)],382 (b) chloroacetaldehyde and a primary amine [producing secondary amines (154)],9 and (c) some nitriles, e.g., malononitrile (to give the primary amine 155).382 The last reaction, however, is by no means a general one, since benzimidazoles are also produced from these substrates (see below). l-Hydroxyquinoxalin-2-one 4-oxides (156) can also be formed in several ways using (a) an a-substituted /1-ketoester (157)... 

A stream of chlorine is led into 3.44 moles of freshly distilled ethylene carbonate (1,3-dioxolan-2-one) under UV-irradiation at 63-70° until a weight increase of 119 g is attained (24 h). Fractional distillation at water-pump vacuum then gives 5.2% of 1,2-dichloroethylene carbonate (3,4-dichloro-l,3-dioxolan-2-one), b.p. 78-79°/l9-20 mm, followed by 69% of the monochloro derivative, b.p. 106-107°/10-11 mm.622 The latter product is treated with one drop of triethylamine and heated in a distillation apparatus slowly to 210° (oil-bath) C02 is split off and chloroacetaldehyde is formed, which collects in the receiver as a clear liquid with a green tinge this reaction requires about 1 hour redistillation through a short column gives the pure aldehyde (9 g), b.p. 84-86°. 

Numerous examples of such reactions (equation 34) have been reported in earlier reviews ". In the well-known standard synthesis of alkoxyalkynes f reaction of acetals of chloroacetaldehyde 52 with sodium amide in liquid ammonia has been used to generate sodium alkoxyacetylide 54. Recently, this elimination procedure has been further improved by using lithium diethylamide in THE solution (equation 35)". In this work" in situ generated lithium alkoxyacetylide 56 was subsequently converted to either ethoxyacetylene 57 by quenching with saturated aqueous sodium diioride, or ethoxyethynyl carbinols 58 by subsequent reaction with ketones or aldehydes. 

---