Formaldehyde, trimer

Summary In this procedure, propionitrile and sulfuric acid are heated together, and then a solution of trioxane (formaldehyde trimer) in propionitrile is slowly added a short time later. Shortly after the addition, a triazine compound is formed. This triazine compound is only an intermediate and need not be isolated. The triazine slurry is then added to ten times it volume of 99% nitric acid. The resulting mixture is then cooled, heated, and then cooled again. The mixture is then drowned into 5 times its volume of water. The RDX then precipitates in high purity. Commercial Industrial note For related, or similar information, see Application No. 522,153, November 8, 1974, by The United States Army, to Joseph A. Meredith, Bluff City, TN. Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

AI3-01363 Aldeform CCRIS 4732 EINECS 203-812-5 Formagene Formaldehyde, trimer HSDB 3416 Marvosan Metaformaldehyde NSC 26347 Para-formaldehyde Polymerized formaldehyde Polyoxy-methylene Triformol Triossimetilene 1,3,5-Trioxa-cyclohexane Trioxan 1,3,5-Trioxan Trioxane s-Tri-oxane ... 

Cross-dimerizing cyclohexane with the formaldehyde trimer gives a material which yields cyclohexanecarboxaldehyde on hydrolysis (equation 46). The radicals formed by Hg reactions of alkanes can also be efficiently trapped by SO2 to give RSO3H after oxidation, and by CO to give RCHO and R2CO F... 

The cross product formed from the formaldehyde trimer can easily be hydrolyzed to QHiiCHO, and so is the equivalent of a CO insertion into a C—H bond. The quantum yields are very good (0.25-0.8). Some of these reactions are even under study for possible commercial application. The light is required to drive the reactions thermodynamically, and they have not yet been made catalytic in photons. 

Polymers with the repeat units -fCH - Of, known as polyacetals, have been known since the early 920 s. It was not until the late 1950 s, however, that research efforts resulted in high molecular weight linear, stable thermoplastic materials. Whereas these developments were directed towards homopolymers of formaldehyde at DuPont, the research at Celanese Corporation was aimed towards copolymers using trioxane, a cyclic formaldehyde trimer, as the major monomer. 

Formaldehyde, H2C=0, is known to all biologists because of its usefulness as a tissue preservative. When pure, formaldehyde trimerizes to give trioxane, CsHeOa, which, surprisingly enough, has no carbonyl groups. Only one monobromo derivative (CaHsBrOa) of trioxane is possible. Propose a structure for trioxane. 

Cyclic acetals (trioxane cyclic trimer of formaldehyde) O—CHo... 

The term "acetal resins" commonly denotes the family of homopolymers and copolymers whose main chains are completely or essentially composed of repeating oxymethylene units (—CH2—O—). The polymers are derived chiefly from formaldehyde or methanal [50-00-00] either directly or through its cychc trimer, trioxane or 1,3,5-trioxacyclohexane [110-88-3]. 

Trioxane and Tetraoxane. The cycHc symmetrical trimer of formaldehyde, trioxane [110-88-3] is prepared by acid-catalyzed Hquid- or vapor-phase processes (147—151). It is a colorless crystalline soHd that bods at 114.5°C and melts at 61—62°C (17,152). The heats of formation are — 176.9 kJ/mol (—42.28 kcal/mol) from monomeric formaldehyde and —88.7 kJ/mol (—21.19 kcal/mol) from 60% aqueous formaldehyde. It can be produced by continuous distillation of 60% aqueous formaldehyde containing 2—5% sulfuric acid. Trioxane is extracted from the distillate with benzene or methylene chloride and recovered by distillation (153) or crystallization (154). It is mainly used for the production of acetal resins (qv). 

Primary aromatic amines react with aldehydes to form Schiff bases. Schiff bases formed from the reaction of lower aUphatic aldehydes, such as formaldehyde and acetaldehyde, with primary aromatic amines are often unstable and polymerize readily. Aniline reacts with formaldehyde in aqueous acid solutions to yield mixtures of a crystalline trimer of the Schiff base, methylenedianilines, and polymers. Reaction of aniline hydrochloride and formaldehyde also yields polymeric products and under certain conditions, the predominant product is 4,4 -methylenedianiline [101 -77-9] (26), an important intermediate for 4,4 -methylenebis(phenyhsocyanate) [101-68-8], or MDI (see Amines, aromatic amines, l thylenedianiline). 

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. 

Di- and Triisobutylcncs. Diisobutylene [18923-87-0] and tnisobutylenes are prepared by heating the sulfuric acid extract of isobutylene from a separation process to about 90°C. A 90% yield containing 80% dimers and 20% trimers results. Use centers on the dimer, CgH, a mixture of 2,4,4-trimethylpentene-1 and -2. Most of the dimer-trimer mixture is added to the gasoline pool as an octane improver. The balance is used for alkylation of phenols to yield octylphenol, which in turn is ethoxylated or condensed with formaldehyde. The water-soluble ethoxylated phenols are used as surface-active agents in textiles, paints, caulks, and sealants (see Alkylphenols). 

The polymer also can be made from trioxane (the trimer of formaldehyde), usually as a copolymer with ethylene oxide. The —CH2CH2— fragments in the copolymer chain prevent depolymerization acetal copolymer was developed by Celanese (10). 

The cyclic trimer (trioxane) and tetramer are obtained by a trace of sulphuric acid acting on hot formaldehyde vapour (i) Figure 19.1). Linear polymers with degrees of polymerisation of about 50 and a terminal hydroxyl group are obtained by evaporation of aqueous solutions of formaldehyde (ii). In the presence of strong acid the average chain length may be doubled. Evaporation of methanol solution leads to products of type (iii). 

The dimer of 1-methyl- -pyrroline (39) was obtained by reduction of N-methylpyrrole with zinc and hydrochloric acid (132) and, together with the trimer, by mercuric acetate dehydrogenation of N-methylpyrrolidine (131). J -Pyrroline-N-oxides form dimers in a similar manner (302). Treatment of 1,2-dimethyl-zl -piperideine with formaldehyde, producing l-methyl-3-acetylpiperidine (603), serves as an example of a mixed aldol reaction (Scheme 18). 

The process can be still more simplified. It is not always necessary to use a pre-formed Schiff s base. Often it is sufficient to bring the carbonyl compound and the amine together in an inert solvent and to add the peracid to the mixture later, - In this way oxaziranes can be obtained in good yield even if the Schiff s base is unknown or can only be obtained in poor yield. For example, formaldehyde gives with aliphatic amines usually only trimers of the Schiff s bases (4). On the other hand, the synthesis of 2-cyclohexyl-oxazirane (5) from cyclohexylamine, formaldehyde, and peracetic acid proceeded in 66%... 

When catalyzed by acids, low molecular weight aldehydes add to each other to give cyclic acetals, the most common product being the trimer. The cyclic trimer of formaldehyde is called trioxane, and that of acetaldehyde is known as paraldehyde. Under certain conditions, it is possible to get tetramers or dimers. Aldehydes can also polymerize to linear polymers, but here a small amount of water is required to form hemiacetal groups at the ends of the chains. The linear polymer formed from formaldehyde is called paraformaldehyde. Since trimers and polymers of aldehydes are acetals, they are stable to bases but can be hydrolyzed by acids. Because formaldehyde and acetaldehyde have low boiling points, it is often convenient to use them in the form of their trimers or polymers. 

Another versatile approach, which nicely complements these Mannich-based procedures, incorporates a preformed symmetrical hexahydro-l,3,5-triazine (HHT) intermediate. In this case the phosphorus reagent reacts with HHT as a trimeric form of the normal aldimine species generated in situ between the amine or amino acid and formaldehyde. These HHT reagents can often be puritied and isolated prior to the reaction with phosphites. They are reasonably stable under neutral or slightly basic conditions, but they can readily revert back to the original amine and formaldehyde after heating with aqueous acid (25). Several can be purchased commercially. 

Aldehydes such as formaldehyde, acetaldehyde, paraformaldehyde, 1,3,5-trioxane, or acetaldehyde-trimer react with trimethyliodosilane (TIS) 17 to give 2,2-di-iodoethers such as 693 and 694 in up to 97% yield [205] (Scheme 5.66). 

Erker and co-workers in 1983 found that Cp2Zr(CO)2 (2) was formed, along with a mixture of other organozirconium products, when oligomeric bis(cyclopentadienyl)dihydridozirconium, (Cp2ZrH2), was stirred in toluene under 148 atm of CO at room temperature for 1 week. While Cp2Zr(CO)2 (2) could be isolated in 30% yield, the product of interest was a novel trimeric (7j2-formaldehyde)zirconocene complex (56). 

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