Trimethylene oxides

A mixture of 150 g. (2.6 moles) of potassium hydroxide and 12 ml. of water is placed in a 500-ml. flask. A thermometer is placed in the reaction mixture, and one neck of the flask is connected to two receivers in series each of which is cooled in an ice-hydrochloric acid mixture. The reaction mixture is heated to 100° (inside temperature) and agitated while 75 g. (0.55 mole) of y-chloropropyl acetate (p. 83) is added slowly over a 1-hour period. The reaction mixture is held at 100-110° during this operation and at 120° for 10 minutes after completion of the addition. The distillates in the receivers from two such runs are combined (29 g.) and cooled in a freezing mixture, and bromine is added dropwise until there is a slight permanent color. The mixture is then distilled from a water bath and the distillate is allowed to stand for 24 hours over anhydrous sodium sulfate. Distillation gives 14 g. (22%) of trimethylene oxide, b.p. 48-50°/750 mm. 

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Other interesting perfluoro ether stmctures can be obtained by copolymerization of hexafluoroacetone with ethylene oxide, propylene oxide, and trimethylene oxide with subsequent fluorination to yield the following stmctures (67) ... 

The four-membered oxetane ring (trimethylene oxide [503-30-0]) has much higher ring strain, and irreversible ring-opening polymerization can occur rapidly to form polyoxetane [25722-06-9] ... 

In 1909, Patemo and Chieffi noted that mixtures of tri- or tetra-substituted olefins and aldehydes formed trimethylene oxides when exposed to sunlight. Biichi later repeated Patemo s experiments by irradiating 2-methyI-2-butene in the presence of benzaldehyde, butyraldehyde, or aeetophenone and rigorously purifying and identifying the resulting products. The reaction thus bears the name of its two primary pioneers and has come to represent any photo-catalyzed [2 + 2] electrocyclization of a carbonyl and an alkene. 

Acetylcyanide adds to olefins to form oxetanes having a useful functional group directly attached to the trimethylene oxide ring(107) ... 

Trimethyl- 1-butene r/.v.r/.v-1.3.5-Trim ethyl cyclohexane Trimethylene oxide... 

The thermodynamics and shock-tube kinetics of pyrolysis of azetidine, in argon at high dilution, have been compared with those for trimethylene oxide, sulfide and imine. ... 

These conclusions are further generalized by the more extensive data presented in Fig. 7 for polyethylene oxide and poly-trimethylene oxide. The continuous nature of the Ti function for both these polymers over a large temperature range is quite definite and is emphasized by the detailed data in the vicinity of the respective melting temperatures. This is true even for the polyethylene oxide samples where discontinuities in the linewidth are clearly indicated in Fig. 7. Obviously, the type of segmental motions which contribute to the two different relaxation pareim-eters are influenced quite differently by the presence of crystallinity. 

Cyclic ethers can be named simply as oxacycloalkanes, such as oxacyclopropane, oxacyclo-butane, oxacyclopentane, and oxacyclohexane, where the prefix oxa indicates the replacement of CH2 by O in corresponding cycloalkanes. Most cyclic ethers, however, are known by other names. The 3-, 4-, 5-, and 6-membered rings are oxirane, oxetane, oxolane, and oxane, respectively, or ethylene oxide (or epoxide), trimethylene oxide, tetrahydrofuran, and tetrahydropyran. 

Oxetane (1.3-trimethylene oxide) [503-30-0] M 58.1, b 45-46 /736mm, 47-49 /atm, Distd from sodium metal. Also purified by preparative gas... 

Oxetane (1.3-trimethylene oxide) [503-30-0] M 58.1, b 45-46°/736mm, 47-49°/atm, 48°/760mm, d4° 0.892, n2D°1.395. Distd from sodium metal. Also purified by preparative gas chromatography using a 2m silica gel column. Alternatively add KOH pellets (50g for lQOg of oxetane) and distil through a column packed with l/4in Berl Saddles and the main portion boiling at 45-50° is collected and redistd over fused KOH. [Noller Org Synth Coll Vol III 835 7955 Dittmer et al. JACS 79 4431 1957]. 

Trimethylene oxide see oxetane. Trimethylene sulphide see thietane. 

Poly(trimethylene oxide) is a very regular polyether chain in a very densely packed random coil. The two C—C skeletal bonds show preference for the gauche configuration while the two C—O bonds show preference for a trans configuration. Polymers of BCMO and 3,3-bis(azidomethyl)oxetane have analogous structures, with the substituents on the central carbons oriented away from each other (77JCP(66)1901,78MI51302). 

Conceivably, therefore, epoxides could form their own co-catalysts or alternatively, any trace of water could promote the formation of further hydroxyl groups. In the case of oxacyclobutane (trimethylene oxide) however the polymerization appears to involve oxonium ions yet the completely dry mixture of monomer and boron fluoride is stable, reacting only on addition of co-catalyst. It seems probable, therefore, that the formation of oxonium ions is catalysed by protons and if so, then the work of Klages and Meuresch (5) is pertinent to the present discussion. These workers found that the ether complexes of acids such as HBF4 and HSbClfi react rapidly and quantitatively with diazomethanes to yield oxonium salts... 

Table 2.4 shows the ratio of molecular diameter to cavity diameter for guests in structures I and II. The corresponding data for structure H is given in Table 2.7, and the data for cyclopropane and trimethylene oxide (which form both si and sll) are also provided. 

Trimethylene oxide (Hawkins and Davidson, 1966), cyclopropane (Hafemann and Miller, 1969 Majid et al., 1969), and ethylene sulfide (Ripmeester, Personal Communication, May 2,1988) are three molecules that can form in either the 51262 of structure I or the 51264 of structure II as simple hydrates. Raman spectroscopy measurements suggest that a low fraction of 512 cages may also be occupied by cyclopropane at high pressures (Suzuki et al., 2001). Such compounds change structures depending on the temperature and pressure of formation, and guest composition in the aqueous phase as discussed in Section 2.1.3. 

Table 2.4 presents the diameter ratios of natural gas components (and a few other compounds) relative to the diameter of each cavity in both structures. Also presented are two unusual molecules, cyclopropane and trimethylene oxide, which can form simple hydrates of either structure si or sll hydrates of these molecules are discussed in Section 2.1.3.3, in the subsection on structural changes in simple hydrates. 

Tables 2.5a,b provide a comprehensive list of guest molecules forming simple si and sll clathrate hydrates. The type of structure formed and the measured lattice parameter, a, obtained from x-ray or neutron diffraction are listed. Unless indicated by a reference number, the cell dimension is the 0°C value given by von Stackelberg and Jahns (1954). Where no x-ray data exists, assignment of structure I or II is based on composition studies and/or the size of the guest molecule. Tables 2.5a,b also indicate the year the hydrate former was first reported, the temperature (°C) for the stable hydrate structure at 1 atm, and the temperatures (°C) and pressures (atm) of the invariant points (Qi and Q2). Both cyclopropane and trimethylene oxide can form si or sll hydrates. Much of the contents of these tables have been extracted from the excellent review article by Davidson (1973), with updated information from more recent sources (as indicated in the tables).

The ideal guest/water ratio is G 5%H20 for molecules that can occupy both cavities of structure I, and G-7(2/3 )H20 for occupants of only the 51262 of structure I. As indicated in Figure 2.13 molecules of transitional size (shaded region) such as cyclopropane (Majid et al., 1969) and trimethylene oxide (Hawkins and Davidson, 1966) with diameters of 5.8 and 6.1 A, respectively, may form either structure. 

Structural Changes in Simple Hydrates. Of particular interest to the question of structure are the simple hydrates of cyclopropane and trimethylene oxide because they can form hydrates of either structure I or structure II as a function of formation conditions. These hydrates are unique examples of structural change of single guest species at different conditions of pressure and temperature. 

Consider cyclopropane, first determined to form each structure by Hafemann and Miller (1969). Because trimethylene oxide is miscible, it has a very dissimilar phase diagram, confounding a comparable analysis. 

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