Paraformaldehyde, preparation

Note 2. Prepared by introducing gaseous HCl at -10°C into a mixture of 30 g of paraformaldehyde (corresponding to 1 mol of formaldehyde) and 1 mol of ethanol, until copious fumes escaped from the mixture. This was cooled (without stirring) to -70°C and the upper layer was decanted from the solid (frozen hydrochloric acid) and mixed with 50 g of yy-diethyl(or dimethyl)aniline. Subsequent distillation in a partial water-pump vacuum afforded the desired chloroether (b.p. about 40°C/40-50 mmHg). 

AIkyl-Ai,A/-diaLkyl-l-naphthalenecarboxamides are useful herbicides (86) and the 2,2-dimeth5lhydra2ide of 1-naphthalenecarboxyhc acid has been patented as a plant growth regulator (87). 2-Propynyl-2-naphthalenecarboxylate [53548-27-9] and similar esters are insecticides (88). 1-Naphthaleneacetic acid, the plant growth regulator, has been prepared from naphthalene, concentrated HCl, and paraformaldehyde without isolation of intermediate 1-chloromethylnaphthalene or l-naphthaleneacetonitnle (89). 

Paraformaldehyde [30525-89-4] is a mixture of polyoxymethylene glycols, H0(CH20) H, with n from 8 to as much as 100. It is commercially available as a powder (95%) and as flake (91%). The remainder is a mixture of water and methanol. Paraformaldehyde is an unstable polymer that easily regenerates formaldehyde in solution. Under alkaline conditions, the chains depolymerize from the ends, whereas in acid solution the chains are randomly cleaved (17). Paraformaldehyde is often used when the presence of a large amount of water should be avoided as in the preparation of alkylated amino resins for coatings. Formaldehyde may also exist in the form of the cycHc trimer trioxane [110-88-3]. This is a fairly stable compound that does not easily release formaldehyde, hence it is not used as a source of formaldehyde for making amino resins. 

W. Lindlaw, The Preparation of Butylated Erea—Formaldehyde and Butylated Melamine Formaldehyde Resins Using Celanese Formcel and Celanese Paraformaldehyde. 

An enzyme-catalyzed appHcation has been used to prepare the enantiomers of hydroxy-substituted tetrahydroisoquinolines (160). The synthesis of ( V)-reticuline [485-19-8] (30) has been reported using similar methodology (161). The substitution of formic acid and paraformaldehyde in this method leads to lower reaction temperatures, freedom from hydrolysis of protective groups, and improved yields (162). 

Bischloromethyl ether has been prepared by saturation of formalin with dry hydrogen chloride by the reaction of paraformaldehyde with phosphorus trichloride or phosphorus oxychloride, by solution of paraformaldehyde in concentrated sulfuric acid and treatment with ammonium chloride or dry hydrogen chloride, and by suspension of paraformaldehyde in seventy or eighty percent sulfuric acid and treatment with chlorosulfonic acid. It is formed together with the asymmetrical isomer when methyl ether is chlorinated and when paraformaldehyde is treated with chlorosulfonic acid. The present method has been published. ... 

Rentsch and his coworkers prepared 1,3,6,9,12-pentaoxacyclotetradecane (/) in 47% yield by heating tetraethylene glycol and paraformaldehyde in benzene solution. 

Similar pentaerythritol cryptands have been prepared by a slight modification of the above approach. Although the general strategy is as illustrated in Eq. (8.11), atfetal formation is accomplished by reaction of pentaerythritol with paraformaldehyde. This reaction leads to diacetal 12 which is hydrolyzed in dilute H2SO4 to yield the monoacetal, 13. The latter is then used in a fashion similar to that described in Eq. 8.10, above. 

The starting material is prepared by the reaction of acetophenone, paraformaldehyde and pyrrolidine to give OJ-pyrrolidinopropiophenone. That is in turn reacted with phenyl magnesium bromide to give 1,1-diphenyl-3-pyrrolidinpropan-1-ol. 

Palladous chloride in preparation of hydrogenation catalyst, 46, 89 Paraformaldehyde, conversion to form aldoximc, 46,13 Pelargonyl fluoride 46, 6 1-Pentalenecaeboxylic acid, octa hydro-, 47,10... 

Linear novolac resins prepared by reacting para-alkylphenols with paraformaldehyde are of interest for adhesive tackifiers. As expected for step-growth polymerization, the molecular weights and viscosities of such oligomers prepared in one exemplary study increased as the ratio of formaldehyde to para-nonylphenol was increased from 0.32 to 1.00.21 As is usually the case, however, these reactions were not carried out to full conversion, and the measured Mn of an oligomer prepared with an equimolar phenol-to-formaldehyde ratio was 1400 g/mol. Plots of apparent shear viscosity versus shear rate of these p-nonylphenol novolac resins showed non-Newtonian rheological behavior. 

An alternative preparation of benzofurans was carried out via a microwave-assisted Mannich condensation of paraformaldehyde and a secondary amine followed by cyclization with an alkynyl phenol 185 mediated by alumina doped with Cul (Scheme 67). The reaction can be carried out in a single-step... 

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]. 

The title compound has also been prepared by alkylations of (tributylstannyl)methanol with chloromethyl methyl ether (55% overall yield from paraformaldehyde) Sawyer, J. S. Kucerovy, A. Macdonald, T, L. McGarvey, G. J. J. Am. Chem. Soc. 1988, 110, 842. 

Reaction of porphyrins with nitrones has also been studied and the results obtained showed that this is a versatile approach leading to the synthesis of isoxazolidine fused-chlorins (Scheme 26). For instance, chlorin 74 was successfully prepared from the reaction of the jV-methylnitrone, generated in situ from JV-methyl hydroxylamine and paraformaldehyde, with porphyrin Id . It is important to note that bis-addition also took place, yielding exclusively bacteriochlorin type derivatives 76 and 77 (Figure 6). This result contrasts with those obtained in 1,3-DC reactions with azomethinic ylides where isobacteriochlorins were obtained preferentially. 

Hydroxylmethyl-l,2,4-triazoles 45a-d may also be prepared by electrophilic substitution by the reaction of the parent 1,2,4-triazoles 44 with paraformaldehyde in refluxing xylene (Equation 12 and Table 2) <2006S156>. 

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