Formaldehyde reaction with aldehydes

Formaldehyde condenses with itself in an aldol-type reaction to yield lower hydroxy aldehydes, hydroxy ketones, and other hydroxy compounds the reaction is autocatalytic and is favored by alkaline conditions. Condensation with various compounds gives methylol (—CH2OH) and methylene (=CH2) derivatives. The former are usually produced under alkaline or neutral conditions, the latter under acidic conditions or in the vapor phase. In the presence of alkahes, aldehydes and ketones containing a-hydrogen atoms undergo aldol reactions with formaldehyde to form mono- and polymethylol derivatives. Acetaldehyde and 4 moles of formaldehyde give pentaerythritol (PE) ... 

The Prins reaction with formaldehyde, acetic acid, acetic anhydride, and camphene gives the useful alcohol, 8-acetoxymethyl camphene, which has a patchouli-like odor (83). Oxidation of the alcohol to the corresponding aldehyde also gives a useful iatermediate compound, which is used to synthesize the sandalwood compound dihydo- P-santalol. 

Several kinds of products can be obtained by reaction of thioglycolic acid and its esters with aldehydes to form mercaptals, RCH(SCH2COOH)2, or with ketones to form thiolketals, RR C(SCH2COOH)2. Reaction with formaldehyde (qv) yields di- -butyhnethylene-bisthioglycolate [1433882-0] (MET ester) ... 

Hydrogen bromide adds to acetylene to form vinyl bromide or ethyHdene bromide, depending on stoichiometry. The acid cleaves acycHc and cycHc ethers. It adds to the cyclopropane group by ring-opening. Additions to quinones afford bromohydroquinones. Hydrobromic acid and aldehydes can be used to introduce bromoalkyl groups into various molecules. For example, reaction with formaldehyde and an alcohol produces a bromomethyl ether. Bromomethylation of aromatic nuclei can be carried out with formaldehyde and hydrobromic acid (6). 

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. 

Amines-Reaction with Formaldehyde and Other Aldehydes... 

The Grignard Reaction is the addition of an organomagnesium. halide (Grignard reagent) to a ketone or aldehyde, to form a tertiary or secondary alcohol, respectively. The reaction with formaldehyde leads to a primary alcohol. 

Once again, ( )-carvone was chosen as starting material (Scheme 48) (727). Aldol reaction with formaldehyde led to 6-hydroxymethylcarvone. The primary alcohol was protected as silylether 415 to permit addition of (cyanomethyl)lithium. The 5 1 mixture of epimeric tertiary alcohols was separated and the main product, 416, the alcohol generated by axial attack, was protected stereoselectively as bromoether 417 utilizing pyridinium hydrobromide perbromide. To introduce the necessary alkyne, the nitrile was reduced to the aldehyde with diisobutylaluminum hydride and subsequent hydrolysis. Addition of the alkyne led to a 2 1 mixture of... 

Further condensation reaction with formaldehyde or other aldehydes... 

Benzyl alcohols can be prepared by reaction with formaldehyde gas or more conveniently with paraformaldehyde (polymethanal) (Scheme 10.5), but reaction with other aldehydes yields secondary alcohols... 

Several preparations of aldehydes have been developed that involve the formation and cleavage of Schiff bases. The condensation of anilines or phenols with formaldehyde and p-nitrosodimethylaniline leads to such intermediates. These substances can be isolated and converted by an exchange reaction with formaldehyde in acetic acid to the corresponding aldehydes. p-Dimethylaminobenzaldehyde is made in this manner in 59% yield. ... 

Whereas the imines formed with aromatic aldehydes are relatively stable, those formed from aliphatic aldehydes are often unstable and undergo further reaction. If the reaction with formaldehyde is carried out with the salt of a primary or secondary amine and a ketone containing an acidic hydrogen, a new C-C bond is formed. This reaction, known as the Mannich reaction (Scheme 2.35), has played a useful role in many syntheses. 

As will be seen in subsequent sections, the HO2 radical is an important combustion intermediate, however, due to its low reactivity, it plays little part in propagating the combustion process via abstractions from fuel molecules. As discussed in Chapter 1, abstraction by HO2 from intermediates such as aldehydes, generates H2O2 and provides a route to branching in the intermediate temperature region. The reaction with formaldehyde has been studied directly as a function of temperature by Jemi-Alade etal. [19]. HO2 radicals were generated by the photolysis of H2CO/O2 mixtures... 

Sarains A-C are a family of alkaloids isolated from marine sponges. J.K. Cha and co-workers accomplished the synthesis of the western macrocyclic ring of sarain To establish the C3 quaternary stereocenter, they treated the aldehyde substrate with formaldehyde in the presence of sodium carbonate. The aldehyde substrate underwent an aldol reaction followed by a Tishchenko reaction to provide the formate ester of the 1,3-diol product. This ester was hydrolyzed in situ under the reaction conditions and the 1,3-diol was isolated. 

Thus a support-bound benzylpiperazine (282) was allowed to undergo a Man-nich reaction with formaldehyde and a-keto-aldehyde hydrazones. Upon addition of 1,2-dibromo-ethane (388) the support-bound piperazine tether is N, N -dialky-lated to give a quinuclidinium species (389). Subsequent Hoffmann elimination released a diazaalkadiene (390) from the polymeric support, allowing it to react with isonitriles to give pyrazoles (395). With electron-rich dienophiles, HDA reactions were also reported to have been performed to yield compound (393) (Scheme 80). 

Dioxanes can also be produced by the acid-catalysed condensation of alkenes with aldehydes, preferably with formaldehydes Prins reaction) ... 

Grignard reaction with formaldehyde closer to our desired product. Subsequent hydrolysis will yield 2,2-dimethylbutanol our desired product is 2,2-dimethylbutanal. Oxidation of the primary alcohol to the aldehyde can be accomplished with Sarett s reagent, a combination of chromium trioxide (CrOs) with pyridine. 

Rodini and Snider demonstrated that dimethylaluminium chloride catalyses an ene reaction between aldehydes and alkenes. As a follow-up they showed that terminal alkynes give a similar reaction with formaldehyde". ... 

Cyanopropionates have also been employed in catalytic aldol reactions. The enolisation of the nucleophile (7.98) by the rhodium complex of TRAP ligand (7.99) is the basis for the catalysis. The use of bulky esters affords high selectivity in the aldol reaction with formaldehyde (7.100), although only moderate antitsyn selectivity was observed when alternative aldehydes were employed. 

Monoimines derived from most aldehydes and ammonia undergo a related, extremely rapid trimerization to produce 2,4,6-trisubstituted 1,3,5-hexahydrotriazines. These reactions also proceed by additions of an imine 1,2-dipole to itself (Refs. 89,90). The reaction of amines with aldehydes to form N,N, N -tiisubstituted-1,3,5-hexahydrotriazineshasaIso been observed amines include anilines and benzylamine. However, with most amines the reaction is limited to reactions with formaldehyde (Refs. 113-116). Only methylamine and allylamine have been observed to produce... 

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