Crotonic anhydride

As noted previously in Chapter 3, the improved dimensional stability of wood as a result of anhydride modification has been found to be a function of WPG only, irrespective of the anhydride used for modification (Stamm and Tarkow, 1947 Hill and Jones, 1996b Li etal., 2000b). This shows that improved dimensional stability arises due to a bulking phenomenon, caused by the volume occupied by the bonded acyl adducts in the cell wall. The dimensional stabilization of wood modified with crotonic anhydride has also been reported ( etin and Ozmen, 2001). Reductions in the EMC have also been attributed to a bulking phenomenon (Papadopoulos and Hill, 2003), and in at least one example of decay protection (Papadopoulos and Hill, 2002). Further research is needed to determine if this is the case for resistance to other decay organisms. Only with the phenomenon of surface wettability does the relationship between a physical property of chemically modified wood and WPG seem to be broken (Hill and Jones, 1996c) (Table 4.1). 

Figure 6.6 Structures of methacrylic anhydride (a) and crotonic anhydride (b).

Qetin, N.S. and Ozmen, N. (2001). Dimensional changes in Corsican and Scots pine sapwood due to reaction with crotonic anhydride. Wood Science and Technology, 35(3), 257-267. 

CH3.CH CHCO.OO.CO.CH CH.CHj mw 170.16, O 37.61% ndls or pits (from petr eth), mp 41°, explodes mildly on further heating sol in common solvs its aq soln slowly hydrolizes was prepd by action of Ba02 on an ethereal soln of crotonic anhydride at 0°(Refs 1 2). 

Vinylketene (1). This ketene has been generated by vacuum pyrolysis of crotonic anhydride (equation I) and identified by low-temperature H and 13C NMR. 

Imino and methyl groups may be annulated by prolonged heating with crotonic anhydride. 

Crotonic anhydride, (CH3CH-=CHC0)20. Mol. wt. 154.16, b.p. 246-248. This reagent is prepared by treatment of crotonic acid with DCC in THF. 

Diallyl ether reacts with SCI2 to afford oxathiocin (129) (Equation (42)) <69BRP1141492), while crotonic anhydride undergoes double Michael addition of hydrogen sulfide to afford oxathio-cindione (132) (Equation (43)) <65BRP1002328>. 

Figure 20.2 CP-MAS C-NMR spectra of pine samples treated with (a) crotonic anhydride, (b) crotonic anhydride followed by copolymerization with styrene, (c) methacryhc anhydride and (d) methacrylic anhydride followed hy copolymerization with styrene. (Reproduced by permission of Elsevier. Copyright 2000. Reprinted from Reference [13].)...

For example, Wang and Cohen showed that IRMOF-3 could be modified with crotonic anhydride to form an amide-functional MOF [Zn40(bdc-NHC(0)-CH=CHMe)3) containing alkenyl groups, which were themselves modified on treatment with bromine (equation 2). 

The fact that many PSM reactions do not go to completion opens up the possibility of a second class of tandem process, during which the second reaction leads to modification of the tag groups that did not react during the first transformation. This is shown schematically in Figure 2b and is illustrated by the reaction of IRMOF-3 with crotonic anhydride, followed by acetic anhydride. If the first reaction is carried out for a limited amount of time, some but not all of the amino groups are modified. Subsequent reaction with the smaller acetic anhydride converts the remaining amino groups into amides. ... 

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