Lead undecylenate

Internal stabilization is a novel method of enhancing the thermal stability of vinyl polymers. Braun, who proposes this term, reports that metal salts of unsaturated carbonic acids are suitable comonomers acting as internal stabilizers. For example, a copolymer of vinyl chloride with only 0.3 mole % of lead undecylenate has a significantly longer and better thermal stability than externally lead-stabilized PVC. 

Considerably better results are obtained with copolymers of vinyl chloride and lead undecylenate. The lead salt of undecylenic acid, (CH2=CH—(CH2)g—COO)2Pb, can be copolymerized by free radicals in bulk or in methanol solution. The composition of the resulting polymer has been determined by infrared spectroscopy (4). Figure 5 shows an infrared spectrum of a film of homopolymeric PVC and of a copolymer obtained from vinyl chloride and lead undecylenate. At wavenumbers... 

Since the absolute extinction depends on the thickness of the film, the extinctions at the characteristic bands mentioned before were taken relative to the extinction at 830 cm."1 to have a measure for the content of lead salt in the copolymer, independent of the dimension of the measured sample. The intensity of the band at 830 cm."1 is of the same order of magnitude as are the intensities of the characteristic band of the lead compound. Furthermore, the absorption at 830 cm."1 is independent of the concentration of the lead salt since it is caused by the rocking oscillation of the PVC CH2-groups and does not interfere with the corresponding oscillation of lead undecylenate at 725 cm."1. 

Evaluation of the spectra of the copolymers indicates that, depending on the content in the monomer mixture, only 40 to 70% of the lead salt is incorporated in the copolymer. In the copolymers obtained by polymerization in methanol solution, practically all lead undecylenate monomer units are incorporated in the chains via both their vinyl groups. Copolymers prepared in bulk, on the other hand, do still contain a noticeable amount of free vinyl groups. 

Because of the low content (up to about 1 mole %) of lead undecylenate monomer units in the copolymers, and because of the relatively low molecular weights of the copolymers (30,000-40,000) they do not contain crosslinked, insoluble portions. 

All copolymers were purified carefully from unreacted lead undecylenate by extraction with suitable solvents. Figure 6 shows the results of dehydrochlorination of some samples at 170 °C. As can be seen, the rate of dehydrochlorination is not only distinctly lower compared with that of PVC, but there is, initially, also a certain period during which no hydrogen chloride is evolved. Although the sample, prepared with 6 wt. % lead salt in the monomer mixture, contains only about 0.3 mole % lead salt in the polymer, it exhibits a remarkable thermal stability at 170 °C. almost no dehydrochlorination occurs within the first 2 hours. This is, therefore, a genuine case of internal stabilization, which finds expression also in the color of the polymer. Discoloration of the samples is substantially less than that of unstabilized PVC the polymer containing 1 mole % lead salt is still nearly colorless after 2 hours of heat treatment. 

Figure 6. Dehydrochlorination of copolymers of vinyl chloride and lead undecylenate at 170°C. under nitrogen. Values on curves designate the amounts (wt. %) of lead salt in monomer mixtures used to prepare copolymers...

Internal stabilization with lead undecylenate appears to be caused for similar reasons. As can be seen in Figure 9, the carbonyl band of the incorporated salt group (obtained from a KBr briquet sample of the copolymer) appears at 1540 cm.-1. The intensity of this absorption band decreases with time of heat treatment. At the same time a band appears at 1730 cm."1 which, in analogy to the investigations of Frye and Horst (10), is to be attributed to formation of ester groups in the polymers. Accordingly, there seems to be no basic difference between the stabilizing action of admixed and of chemically incorporated lead salts of aliphatic carboxylic acids. 

Figure 9. Infrared spectra of copolymer of vinyl chloride ana 0.3 mole % lead undecylenate before and after heat treatment (KBr briquet sample)...

Cracking of the ester at about 500°C leads to the formation of the undecylenic acid ester together with such products as heptyl alcohol, heptanoic acid and heptaldehyde. Undecylenic acid may then be obtained by hydrolysis of the ester. Treatment of the acid by HBr in the presence of a peroxide leads to w-bromoundecanoic acid together with the 10-isomer, which is removed. Treatment of the w-bromo derivative with ammonia leads to w-aminoundecanoic acid, which has a melting point of 50°C (Figure 18.8). 

In order to confirm the reactivity and selectivity of lead ruthenates for the oxidation of isolated double bonds, two soluble, unsaturated carboxylic acids were chosen that contain a double bond far removed from the solubilizing carboxylate group. The two olefinic compounds, 1-undecylenic acid and 2-cyclopentene-l-acetic acid were both cleaved at the double bond as shown in Figure 13. 

The pyrolysis step is not particularly efficient at yielding methyl undecylenate [7] straightforward techniques lead to low yields of 17-35% whereas newer techniques can reach values between 45-50%. By including these process values and starting chemical composition, the overall yield to undecenoic acid is rather low 15-20% of the original castor bean mass. 

Acenaphthene n-Amyl alcohol Arachidic acid Arachidyl alcohol Benzidine dihydrochloride 2-Butyl octanoic acid Butyloctanol Calcium sulfate Cetylarachidol Cocamine Cocopropylenediamine Cyclodextrin p-Cyclodextrin 1,10-Decanediol 2-Decyl tetradecanoic acid Dihydroxyethyl cocamine oxide Dodecylhexadecanol 2-Hexyl decanoic acid Hydroxypropyl-o-cyclodextrin Hydroxypropyl-P-cyclodextrin Hydroxypropyl-y-cyclodextrin 12-Hydroxystearyl alcohol Isobutyl oleate Kelp Lead phthalate, basic Methoxyethanol 2-Methoxy-5-nitroaniline Methoxy tripropylene glycol acrylate Methylene chloride 2-Octyl dodecanoic acid Oleamine PEG-25 castor oil PEG-30 castor oil PEG-36 castor oil PEG-40 castor oil PEG-200 castor oil PEG-5 hydrogenated castor oil PEG-25 hydrogenated castor oil Polyamide Polysorbate 85 Pyridine Quartz Sodium isopropyl naphthalene sulfonate Soybean (Glycine soja) meal Sucrose Sulfur Tallow amine N-Tallow-1,3-diaminopropane dioleate p-Toluene sulfonic acid Tri methyl amine Tungstic acid Undecylenic acid Vinyl compounds and polymers plastics additive... 

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