Olefins reaction with formaldehyde

Uracil derivatives 92 are usually aminomethylated at position 3, although the reaction with formaldehyde alone shows an equilibrium constant for hydroxymethylation in position 1, which is about twice the value obtained for the reaction at position 3. The C-aminomethylation reaction takes place at position 5, when unsubstituted, as these substrates resemble the structure of push-pull olefines (67, Table 8). ... 

Copolymerizations of aldehydes take place by both anionic and cationic mechanisms. An elastic copolymer of formaldehyde and acetaldehyde forms with triisobutylaluminum. The rate of copolymerization is veiy rapid at 78°C. The reaction is complete within 30 min [364]. The product, however, is crosslinked. Aldehydes also copolymerize with some vinyl monomers [386]. An acetone block copolymer forms [387] with propylene when Ziegler-Natta catalysts are used at —78 C. Copolymers of acetone with other olefins and with formaldehyde were also prepared [388, 389]. Many initiators are effective in copolymerizations of aldehydes, ketones, and epoxies [387, 390]. 

Primary nitroparaffins react with two moles of formaldehyde and two moles of amines to yield 2-nitro-l,3-propanediamines. With excess formaldehyde, Mannich bases from primary nitroparaffins and primary amines can react further to give nitro-substituted cycHc derivatives, such as tetrahydro-l,3-oxa2iaes or hexahydropyrimidines (38,39). Pyrolysis of salts of Mannich bases, particularly of the boron trifluoride complex (40), yields nitro olefins by loss of the amine moiety. Closely related to the Mannich reaction is the formation of sodium 2-nitrobutane-1-sulfonate [76794-27-9] by warming 1-nitropropane with formaldehyde and sodium sulfite (41). 

The reaction of a cepham primary amine with 20 eq. of 37% formalin produces the dioxazine in 75% yield. The dioxazine is sufficiently stable to allow the formation of Wittig reagents and to carry out an olefination with formaldehyde. Treatment of the dioxazine with 6 N HCl in CH2CI2 releases the amine in excellent yield. ... 

The initial step is the protonation of the aldehyde—e.g. formaldehyde—at the carbonyl oxygen. The hydroxycarbenium ion 6 is thus formed as reactive species, which reacts as electrophile with the carbon-carbon double bond of the olefinic substrate by formation of a carbenium ion species 7. A subsequent loss of a proton from 7 leads to formation of an allylic alcohol 4, while reaction with water, followed by loss of a proton, leads to formation of a 1,3-diol 3 " ... 

Terminal olefins such as 1476 react in an unusual Prins reaction [33] with formaldehyde in F3CC02H/Me3SiCl 14 to give in ca 75-90% yield a mixture of the cis/ trans 3,4-disubstituted tetrahydrofurans 1477 and 1478 [34] (Scheme 9.19). 

Treatment of the reduced intermediate (23-6) with butyl hthium leads to the anion from the removal of a proton on the methylene group reaction of that with methyl acetate affords the methyl ketone (24-1), which contains two of the three required side chain carbon atoms. The additional carbon atom and the basic function are incorporated by means of a Mannich condensation. Thus, reaction of (24-1) with A-methylpiperazine and formaldehyde leads to the aminoketone (24-2). The carbonyl group is then reduced with sodium borohydride and the resulting alcohol is dehydrated by reaction with phosphoms oxychloride in pyridine. In this case, too, the Z isomer is responsible for most of the activity. This is isolated from the resulting mixture of olefins to afford thiothixene (24-3) [25]. 

Major destruction routes of OH radicals are the addition to olefins, the 11 atom abstraction from olefins and aldehydes, and the reaction with C( > Another radical, hydroperoxyl (H02), has been considered as a major oxidizing agent for NO and to a lesser extent for hydrocarbons. The HO, radicals are probably formed by the photolysis of formaldehyde [see Section VI1-4, p. 277]... 

Bawn and Skirrow (6) found that formaldehyde reduced the induction period in the gas phase oxidation of the simpler olefins such as propylene, 2-butene, and 1-hexene. Data for propylene are given in Table II. An analysis of the products from the reaction of 50 mm. of propylene and 140 mm. of oxygen at 340° C. gave the ratio of formaldehyde to total aldehyde to peroxide as 3 to 25 to 5 after a 7-minute induction period. 2-Butene, oxidized at 290° C. and a total pressure of 82.5 mm., gave formaldehyde, acetaldehyde, and acrolein as the aldehydic products, with formaldehyde, as in the case of propylene, appearing in relatively small amounts. 

Hydrogenated furans can be prepared from the reaction of 7-olefins with formaldehyde in trifluoroacetic acid kinetics suggest that die reactions proceed via equilibrium addition of the protonated aldehyde.184... 

In the first route, methylbutenol is made from acetone and acetylene followed by hydrogenation. Reaction with methyl isopro-penyl ether yields methylheptenone (6). The second route involves the reaction of isobutylene, formaldehyde and acetone (7 ). Methyl vinyl ketone is an intermediate. Finally, methylheptenone is made by alkylation of acetone with prenyl chloride which is derived from isoprene (8). The initial product is the terminal olefin which is isomerized to the desired isopropylidene compound. 

Corey and Yamamoto 233) used the P-oxido synthesis 2341 of trisubstituted olefins for the preparation of the acyclic sesquiterpene famesol 433. In this preparation the isoheptenylphosphonium salt 430 is converted into the hydroxyfamesol derivative 432 by reaction with the tetrahydropyranyl ether — protected hydroxy aldehyde 431 and formaldehyde 205. 432 is converted into famesol 433 via several steps. Other reactions of432 likewise proceeding via several steps lead to 434 which is a positional isomer of a C17-juvenile hormone 233) (Scheme 75). 

An alternative method to the Baeyer-Villiger reaction is that of oxidation with formaldehyde oxide. The latter can be generated by treatment of vinyl acetate with ozone, which gives, beside the wanted products, the mixed anhydride of acetic and formic acid. If a ketone is added to the ozonide mixture, formaldehyde oxide can be trapped to yield the corresponding ozonide, which on thermal decomposition forms the lactone and (or) the corresponding olefinic carboxylic acid. The transformation of camphor (11/202) to the lactone 11/203 by this method has been achieved in 63% yield [131]. 

In the Cannizzaro reaction (62), which involves self-condensation of aldehydes that have no a-hydrogen atoms, the nucleophile is represented best as a hydride ion in the Prins reaction (26), the nucleophile is an olefin in the aldol condensation (63) and reaction of methyl acetate with formaldehyde (62), the nucleophile is a methylene group a- to a... 

Olefination of aldehydes with the a-fluoroalkylphosphine oxide (54) provides a highly stereoselective route to the (Z)-fluoroalkenes (55) (Scheme 9).31 A similar reaction with the corresponding phosphonate gave a 1 1 mixture of ( )- and (Z)-alkenes. A new one-pot synthesis of 2-(diphenylphosphinoyl)cycloalkanes (56) by the reaction of cycloalkanone enolates with chlorodiphenylphosphine followed by oxidation has been reported (Scheme 10).32 Attempts to synthesise sarkomycin methyl ester (58) via reaction of the anion of phosphine oxide (57) with formaldehyde were unsuccessful as were similar reactions with other aldehydes, although the corresponding phosphonate anion does undergo olefination reactions. An X-ray structural analysis of (57) is reported. 

However, near the Earth s surface, the hydrocarbons, especially olefins and substituted aromatics, are attacked by the free atomic O, and with NO, produce more NO2. Thus, the balance of the reactions shown in the above reactions is upset so that O3 levels build up, particularly when the Sun s intensity is greatest at midday. The reactions with hydrocarbons are very complex and involve the formation of unstable intermediate free radicals that undergo a series of changes. Aldehydes are major products in these reactions. Formaldehyde and acrolein account for 50% and 5%, respectively, of the total aldehyde in urban atmospheres. Peroxyacetyl nitrate (CH3COONO2), often referred to as PAN, and its homologs, also arise in urban air, most likely from the reaction of the peroxyacyl radicals with NO2. 

Biological systems overcome the inherent unreactive character of 02 by means of metalloproteins (enzymes) that activate dioxygen for selective reaction with organic substrates. For example, the cytochrome P-450 proteins (thiolated protoporphyrin IX catalytic centers) facilitate the epoxidation of olefins, the demethylization of N-methyl amines (via formation of formaldehyde), the oxidative cleavage of a-diols to aldehydes and ketones, and the monooxygenation of aliphatic and aromatic hydrocarbons (RH).3... 

The Prins reaction is the Bronsted1 or Lewis acid1 catalyzed addition of aldehydes or ketones to olefins. The reaction of simple olefins with formaldehyde is usually nonstereospecific. Addition of the activated carbonyl group to the alkene generates a /1-hydroxycarbenium ion which undergoes configurational relaxation before being trapped in a second step. Several reactions are known which convert the cationic intermediate into a stable product. 

The condensation of formaldehyde and olefins is of industrial interest. Generally anti addition of the oxonium ion and nucleophile to the double bond predominates. The reaction of (E)-butene with formaldehyde in the presence of hydrochloric acid gives a mixture of anlijsyn (85 15) products. 

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