Resins derivatisation

There is a large range of resins available for SPOS. These resins are derivatised polymer supports with a range of linkers. The roles of linkers are (i) to provide point(s) of attachment for the tethered molecule, akin to a solid supported protecting group(s), (ii) to provide distance from the polymeric backbone in order to minimise interactions with the backbone, (iii) to enable cleavage of product molecules under conditions compatible with the stability of the molecules and the reaction conditions employed for chemical transformations. Hence in order to... 

Plant resins are discussed in detail in Chapter 12. Since plant resins were once common additives for paint binders, this section briefly reviews the literature, focusing on the use of different derivatising agents. 

Fresh plant resins have been characterised by means of pyrolysis coupled to GC/MS without the use of a derivatising agent. However, many markers used for the identification of resins in samples from works of art are often not cogent, and moreover they disappear during ageing [42]. 

The derivatised resin product was suspended in DCM (6 mL) for 30 min, after which TEA (0.06 mL) was added and the resultant suspension was gently stirred for 15 min at ambient temperature. The suspension was filtered, the spent resin washed with DCM (5mL) and DCM MeOH (1 1, 5mL), and the combined filtrate was evaporated to dryness in vacuo to afford the title compound (25 mg, 73%) as a white crystalline solid. RP-HPLC analysis (Gl) showed the exclusive presence (>98%) of Fmoc-Val-NHOH (Rt = 5.1 min). 

Twenty-eight of fifty-four samples purchased were found to have coatings made from polyester resins and so their contents were analysed for TPA and IPA. Analysis was by GC-MS after extraction and derivatisation to form the dimethyl esters of TPA and IPA. Included in the analytical quality assurance steps taken was participation in a check-sample exercise whereby four samples were supplied by a second laboratory and analysed blind. The performance of the testing laboratory was assessed from the accuracy and precision of their measurements and was demonstrated to be acceptable. 

Some methods which do not involve separation of the FFAs from the milk fat or the whole product have considerable appeal because of their simplicity. Sharma and Bindal (1987) exploited the property of methyl urea to complex triglycerides in producing methyl esters with BF3-methanol without first separating the FFAs from the fat, while Spangelo et al. (1986) were able to methylate FFAs in an acetonitrile extract of milk with methyl iodide in the presence of an anion exchange resin as catalyst. Miwa and Yamamoto (1990) derivatised the FFAs in milk and milk products for HPLC analysis by direct reaction with 2-nitrophenylhydrazine hydrochloride. 

Figure 5.9 Comparison between GC-MS analysis of 3-mercaptohexan-l-ol (3-MH) and 3-mercaptohexanol acetate (3-MHA) in wine by HS-SPME without on-fiber derivatisation and by SPE using ENV+-type resin enrichment. (From Gas Chromatography-Mass Spectrometry determination of 3-mercaptohexan-l-ol and 3-mercaptohexyl acetate in wine. A comparison between Solid Phase Extraction and Headspace Solid Phase Microextraction methods, Fedrizzi et al., 2007b, Anal. Chim. Acta, 596(2), 291-297)...

As outlined in Scheme 4.4.1, starting from commercially available Fmoc-amino acid derivatised Wang resins 247, or those prepared by known loading procedures, deprotection with 20%... 

A suitable method for determining the anhydride group is titration with aqueous potassium hydroxide in pyridine after previous esterification of the carboxyl group with diazomethane. This esterification is carried out in diethyl ether methanol (9 + 1). After methylation, which takes about 10 minutes for 0.5 g of sample, solvents are removed by evaporation and a portion of the derivatised polymer is dissolved in pyridine and titrated. In the IR spectra of the resin before and after methylation, the absorption band of the acid group at 1710 cm (5.84 pm) disappears and a carbonyl band of the ester at 7104 cm (5.74 pm) is formed. The acid content of the sample is found from the difference in titres of an unmethylated and a methylated product. 

Obt. industrially by catalytic oxidn. of Naphthalene. Used in manuf. of phthalic esters and resins. Dehydrating agent for alcohols, protecting reagent for aminoacids. Derivatisation reagent in the anal, of alcohols. Needles (EtOH). Spar. sol. H2O, Et20, sol. EtOH. Mp 131.8°. 

Table 13.7 Results of quantitative analyses obtained for three PPO resins using 1,3,2-dioxaphosphat-amyl chloride 9 as the derivatising reagent ...

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