Copolymer. Acetal copolymers are prepared by copolymerization of 1,3,5-trioxane with small amounts of a comonomer. Carbon-carbon bonds are distributed randomly in the polymer chain. These carbon-carbon bonds help to stabilize the polymer against thermal, oxidative, and acidic attack.  [c.1012]

Oxygen Acetaldehyde, acetone, alcohols, alkali metals, alkaline earth metals, Al-Ti alloys, ether, carbon disulflde, halocarbons, hydrocarbons, metal hydrides, 1,3,5-trioxane  [c.1210]

Trioxane Oxidizing materials, acids  [c.1212]

Cyclic acetals (trioxane cyclic trimer of formaldehyde) O—CHo  [c.333]

Polymerization. Paraldehyde, 2,4,6-trimethyl-1,3-5-trioxane [123-63-7] a cycHc trimer of acetaldehyde, is formed when a mineral acid, such as sulfuric, phosphoric, or hydrochloric acid, is added to acetaldehyde (45). Paraldehyde can also be formed continuously by feeding Hquid acetaldehyde at 15—20°C over an acid ion-exchange resin (46). Depolymerization of paraldehyde occurs in the presence of acid catalysts (47) after neutralization with sodium acetate, acetaldehyde and paraldehyde are recovered by distillation. Paraldehyde is a colorless Hquid, boiling at 125.35°C at 101 kPa (1 atm).  [c.50]

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].  [c.56]

Acetal resins were first commercialized by Du Pont in 1960 under the tradename Delrin (registered trademark of E. I. du Pont de Nemours and Co., Inc.) Introduction of the then new engineering plastics followed development of suitable processes for the preparation of high molecular weight formaldehyde homopolymer (5) and for the requisite conversion of the homopolymer s unstable end groups by a procedure known as end-capping (6). Development and commercialization of copolymers of trioxane with cychc ethers (eg, ethylene oxide) by Celanese (7) quickly followed in 1962. The copolymers did not require end-capping. Rather, good polymer stabiUty could be achieved by ablation of unstable polymer fractions by a suitable process (8). Today there are ten producers of acetal resins, mostly copolymers.  [c.56]

The many commercially attractive properties of acetal resins are due in large part to the inherent high crystallinity of the base polymers. Values reported for percentage crystallinity (x ray, density) range from 60 to 77%. The lower values are typical of copolymer. Poly oxymethylene most commonly crystallizes in a hexagonal unit cell (9) with the polymer chains in a 9/5 helix (10,11). An orthorhombic unit cell has also been reported (9). The oxyethylene units in copolymers of trioxane and ethylene oxide can be incorporated in the crystal lattice (12). The nominal value of the melting point of homopolymer is 175°C, that of the copolymer is 165°C. Other thermal properties, which depend substantially on the crystallization or melting of the polymer, are Hsted in Table 1. See also reference 13.  [c.56]

Copolymerisation of trioxane with cycHc ethers or formals is accompHshed with cationic initiators. Boron trifluoride dibutyl etherate is used in one process. In this case, the actual initiating species is formed by reaction with water (18). Polymerisation by ring opening of the 6-membered ring to form high molecular weight polymer does not commence immediately upon mixing monomer and initiator. Rather, an induction period is observed during which an equihbrium concentration of formaldehyde is produced (18,19).  [c.58]

When the equihbrium formaldehyde concentration is reached, polymer begins to precipitate. Further polymerisation takes place in trioxane solution and, more importantly, at the surface of precipitated polymer.  [c.58]

Acetal Resins. These are high performance plastics produced from formaldehyde that are used for automotive parts, in building products, and in consumer goods. Acetal resins (qv) are either homopolymers or copolymers of formaldehyde. Typically, the resin is produced from anhydrous formaldehyde or trioxane. The acetal resins formaldehyde demand are 9% of production (115).  [c.497]

Cyclic ether and acetal polymerizations are also important commercially. Polymerization of tetrahydrofuran is used to produce polyether diol, and polyoxymethylene, an excellent engineering plastic, is obtained by the ring-opening polymerization of trioxane with a small amount of cycHc ether or acetal comonomer to prevent depolymerization (see Acetal resins Polyethers, tetrahydrofuran).  [c.246]

Polyoxymethylene Ionomers. Ionic copolymers have been prepared from trioxane and epichlorohydrin, followed by reaction with disodium thioglycolate (76). The ionic forces in these materials dismpt crystalline order and increase melt viscosity (see Acetalresins).  [c.409]

Acetal Resins. Polyacetals are either homopolymer [9002-81-7] or copolymer [95327 3-8] thermoplastics (see Acetal resins). Both are based on formaldehyde [50-00-0] through acetals or trioxane and are highly crystalline strong, and rigid with high melting points. They are made in a variety of grades with different melt indexes and are processed easily by extmsion or injection mol ding. They can be reinforced with glass or fluorocarbon fibers and can be pigmented. Both have high resistance to creep and abrasion and low coefficients of friction. They are used as engineering resins and in building products for plumbing fittings such as ball cocks, faucets, pumps, and valves, which are subject to steady wear and must retain close dimensional tolerances. Polyacetals are flammable however, because of the high oxygen content, they bum cleanly and produce no smoke (2—5).  [c.328]

POSNER Trioxane synth sls  [c.304]

The conventional electrochemical reduction of carbon dioxide tends to give formic acid as the major product, which can be obtained with a 90% current efficiency using, for example, indium, tin, or mercury cathodes. Being able to convert CO2 initially to formates or formaldehyde is in itself significant. In our direct oxidation liquid feed fuel cell, varied oxygenates such as formaldehyde, formic acid and methyl formate, dimethoxymethane, trimethoxymethane, trioxane, and dimethyl carbonate are all useful fuels. At the same time, they can also be readily reduced further to methyl alcohol by varied chemical or enzymatic processes.  [c.220]

The details of the commercial preparation of acetal homo- and copolymers are discussed later. One aspect of the polymerisation so pervades the chemistry of the resulting polymers that familiarity with it is a prerequisite for understanding the chemistry of the polymers, the often subde differences between homo- and copolymers, and the difficulties which had to be overcome to make the polymers commercially useful. The ionic polymerisations of formaldehyde and trioxane are equiUbrium reactions. Unless suitable measures are taken, polymer will begin to revert to monomeric formaldehyde at processing temperatures by depolymerisation (called unsipping) which begins at chain ends.  [c.57]

The enthalpy of the copolymerization of trioxane is such that bulk polymerization is feasible. For production, molten trioxane, initiator, and comonomer are fed to the reactor a chain-transfer agent is in eluded if desired. Polymerization proceeds in bulk with precipitation of polymer and the reactor must supply enough shearing to continually break up the polymer bed, reduce particle size, and provide good heat transfer. The mixing requirements for the bulk polymerization of trioxane have been reviewed (22). Raw copolymer is obtained as fine emmb or flake containing imbibed formaldehyde and trioxane which are substantially removed in subsequent treatments which may be combined with removal of unstable end groups.  [c.58]

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).  [c.498]

Most ozonolysis reaction products are postulated to form by the reaction of the 1,3-zwitterion with the extmded carbonyl compound in a 1,3-dipolar cycloaddition reaction to produce stable 1,2,4-trioxanes (ozonides) (17) as shown with itself (dimerization) to form cycHc diperoxides (4) or with protic solvents, such as alcohols, carboxyUc acids, etc, to form a-substituted alkyl hydroperoxides. The latter can form other peroxidic products, depending on reactants, reaction conditions, and solvent.  [c.117]

Cyclic 1,2,4-trioxanes (18 and 19) have been obtained from the photosensitized oxidation of fiirans (10,44,163). These compounds are  [c.118]

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.  [c.323]

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).  [c.36]

Trioxanes bond angles, 3, 949 bond lengths, 3, 949 H NMR, 3, 952 ionization potential, 3, 959 IR spectra, 3, 956 photoelectron spectroscopy, 3, 959 radical cations  [c.915]

See pages that mention the term Trioxane : [c.319]    [c.319]    [c.319]    [c.294]    [c.415]    [c.421]    [c.488]    [c.506]    [c.580]    [c.611]    [c.689]    [c.381]    [c.1022]    [c.1023]    [c.1023]    [c.1025]    [c.114]    [c.117]    [c.293]    [c.266]    [c.378]    [c.251]    [c.76]    [c.915]    [c.1995]    [c.2102]   
Textbook on organic chemistry (1974) -- [ c.319 ]

Plastics materials (1999) -- [ c.22 ]

Organic syntheses Biclormethyl ether (1956) -- [ c.30 , c.51 ]