Monofunctional alcohols oxidation

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

To the first category belong the homo- and copolymerization of macromonomers. For this purpose, macromolecules with only one polymerizable end group are needed. Such macromonomers are made, for example, by anionic polymerization where the reactive chain end is modified with a reactive vinyl monomer. Also methacrylic acid esters of long-chain aliphatic alcohols or monofunctional polyethylene oxides or polytetrahydrofurane belong to the class of macromonomers. 

It now remains for us to consider the oxidation of monofunctional alcohols and molecules containing the -OH group remote from other functions. The conversion of methanol to formaldehyde (methanal) can be performed either by dehydrogenation (difficult, see Chapter 9) or by oxidative dehydrogenation according to the equation ... 

Polar functional groups such as alcohols or phenols 11 or trimethylsilanol 4 are transformed by monofunctional silylating reagents Me3SiX 12 into their hpophilic and often volatile trimethylsilyl ethers 13 whereas water is converted into persilyl-ated water (=Me3SiOSiMe3, hexamethyldisiloxane, HMDSO, 7, b.p. 100 °C). The persilylation of phenols and, in particular, catechol (or hydroquinone) systems (Scheme 2.1) protects them efficiently against air oxidation even at temperatures of up to 180 °C. (cf, e.g., the silylation-amination of purine nucleosides with dopamine hydrochloride in Section 4.2.4)... 

Polyethylene oxide)macromonomers were also prepared by reaction of methacryloyl chloride with living monofunctional poly(ethylene oxide) I6) the polymerization of which can be efficiently initiated by diphenylmethyl potassium25 or by potassium alkoxides 26 >. In the latter case care must be taken to avoid any excess of alcohol which would play the role of a transfer agent and impede the macromonomer synthesis. The obtained macromonomers... 

Double bonds are cleaved by a number of oxidizing agents, converting the olefinic carbons to carboxylic acids, aldehydes, or alcohols. Fatty acids give a monofunctional product from the methyl end and a difunctional product from the carboxyl end (along with low-molecular-weight products from methylene-interrupted systems). 

Monofunctional heme catalases are usually homotetramers, of molecular weight 200-340 kDa. They have been identified in organisms from bacteria to human. Their typical features include rather strong absorption at the Soret band and irreversible inhibition by a suicide inhibitor, 3-amino-l,2,4-triazole. They are very efficient as catalases (kcat=4xl0 M" s" for human erythrocyte catalase). They can also catalyze 2-electron oxidation of short-chain aliphatic alcohols at reasonable rates [198]. 

Blocked isocyanates permit making coatings that are stable at ambient temperature when baked, the monofunctional blocking agent is volatilized and the coreactant is cross-linked. An extensive review of blocked isocyanates, their reactions, and uses is available (127). The blocking agents most widely used are phenols, oximes, alcohols, e-caprolactam (hexahydro-2ff-azepin-2-one) [105-60-2], 3,5-dimethylpyrazole, 1,2,4-triazole, and diethyl malonate (propanedioic acid diethyl ester) [105-53-3]. A variety of catalysts are used DBTDL is most widely used but many other catalysts have also been used. Bismuth tris(2-ethyl hexanoate) has been particularly recommended (128). In electrodeposition primers, DBTDL has insufficient hydrolytic stability, and tributyltin oxide is an example of an alternate catalyst (129). Cyclic amidines, such as l,5-diazabicyclo[4.3.0]non-5-ene, are reported to be superior catalysts for use with uretdione cross-linkers in powder coatings (130). 

In the preparation of the AB surfactants, a monofunctional initiator (i.e., one having a single acidic hydrogen) such as a monohydric alcohol (ROH), an acid (RCOOH), a mercaptan (RSH), a secondary amine (RR NH), or an TV-substituted amide (RCONR H) is employed as the initiator. A controlled feed of the A oxide is added to obtain the desired average degree of polymerization, m, after which the feed of the B oxide is started. Such materials would generally be given by the formula... 

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