Cadmium stearate

Rothberg L, Higashi G S, Allara D L and Garoff S 1987 Thermal disordering of Langmuir-Blodgett-films of cadmium stearate on sapphire Chem. Phys. Lett. 133 67-72... 

The sohd soaps are prepared from cadmium chloride solution by precipitation with sodium salts of the fatty acids. Cadmium laurate [2605-44-9] Cd(C22H2402)2, cadmium stearate [2223-93-0] cadmium palmitate [6427-86-7] and cadmium myristate [10196-67-5] ... 

Courtesy of Synthetic Organic Chemicals, U.S. Production and Sales, U.S. International Trade Commission. Less than 100 t of cadmium stearates produced ia all years except 1986 for which production was 350 t. Also 160 t cobalt stearates. 

Comparative tests performed on a Ro-Tap unit, a vibrating unit (Sonic Sifter — Allen-Bradley), and the Alpine Air Jet Sieve are shown in Figs 6 and 7. Fig 6 is a powdered cement Fig 7 is cadmium stearate, a waxlike material which clogs easily. These separations were all made on a 42 micron mesh sieve. These tests showed that the Alpine Jet Sieve effected good separations in a matter of minutes compared with the much longer times required for the other systems... 

It was concluded that approximately three minutes sieving time was adequate with the air-jet sieve even with waxlike materials such as cadmium stearate whereas, 20 minutes or longer was required for vibrating or shaking screens. The data presented (Refs 19 35) for AP by the Alpine, Tyler Ro-Tap, and Micromerograph agree remarkably well... 

X-ray diffraction has been applied to spread monolayers as reviewed by Dutta [67] and Als-Nielsen et al. [68], The structure of heneicosanoic acid on Cu and Ca containing subphases as a function of pH has been reported [69], as well as a detailed study of the ordered phases of behenic acid [70], along with many other smdies. Langmuir-Blod-gett films have also been studied by x-ray diffraction. Some recent studies include LB film structure just after transfer [71], variations in the structure of cadmium stearate LB films with temperature [72], and characterization of the structure of cadmium arachidate LB films [73], X-ray [74,75] and neutron reflectivity [76,77] data on LB films can be used to model the density profile normal to the interface and to obtain values of layer thickness and roughness. 

Other work in this general area has shown that the photooxidation of PVC is retarded by zinc and cadmium stearates (63) and by Bu2SnCl2 (68), although it is accelerated by Bu2SnO and Bu2SnCl(SCH2C02-"isooctyl") (68). Butyltin trichloride first retards and then accelerates the photooxidation process (68). 

RA and transmission techniques [3], and applied it to the studies of LB films of cadmium stearate [3], azobenzene-containing long-chain fatty acids and their barium salts [4], dipalmitoylphosphatidylcholine (DPPC) [5], and polyion complexes [6]. Furthermore, we explored the relationship between the molecular orientation evaluated by this method and pyroelectricity in alternating (noncentrosymmetric) Y-type LB films consisting of a phenylpyrazine-containing long-chain fatty acid and deuterated stearic acid and of their barium salts [7]. 

Chlorine-containing polymers such as poly(vinyl chloride) PVC undergo an autocatalytic dehydrochlorination reaction under the influence of elevated temperature and UV radiation. Since the HCl originating from the dehydro chlorination of the PVC chains is believed to sustain this autocatalytic process, stabilizers that irreversibly bond HCl can thus inhibit the degradation. Heavy metal compounds such as cadmium stearate or lead stearate are currently used for this purpose. However, alternatives are required due to environmental problems associated with the use of heavy metals. Indeed, the largest current application of LDH materials is in the polymer industry, mainly to stabilize PVC [3,229-232]. 

The products are usually crystalline, avoiding the need for a high temperature post-treatment [64]. Gautam et al. [65] has introduced an inexpensive, low boiling solvent under solvothermal conditions in the presence of dodecanethiol as a capping agent, using cadmium stearate as a source monodispersed 3 nm CdSe particles can be prepared. 

One of the first examples of addition of a zinc enolate to an alkyne was a report dealing with the zinc or cadmium stearate-catalyzed addition of substituted malonates to acetylene under pressure250. Later, Schultze described the intermolecular nucleophilic addition of the zinc enolate derived from diethyl bromomalonate to phenylacetylene in refluxing xylene leading to the alkylidene malonate 392 (equation 171)251. 

Recent relevant work has made use of transmission electron diffraction, the theory of which we discussed in Section 2.5. This technique has a very straightforward interpretation which, combined with improved experimental methods, has provided very precise results. Two papers are of particular importance in this context. Garoff et al. [137] studied monolayers of cadmium stearate. Their substrates were 2 nm layers of SiO coated on 10 nm layers of amorphous carbon on 200 mesh Ni elec-... 

The behaviour reported above has to be reconciled with the other well known properties of multilayers of cadmium stearate and cadmium arachidate. One possible picture is that these materials deposit in a hex-atic structure which, for a multilayer, represents a metastable state. The upper part of the multilayer, where the molecules are free to move, tends... 

Figure 3 The electron energy distribution of photoelectrons from gold coated with one (A), three (B), five (C) and thirteen (D) monolayers of cadmium stearate.

The butanone-soluble, chloroform-insoluble portion, with all non-cadmium-containing additives, increases from 18 to about 40-62%. This increase exceeds that attributable to the crosslinking of Fraction I. Therefore, at least part of this butanone-soluble fraction comes from a previously butanone-insoluble fraction—t.e., from Fraction III. Such a change would imply chain scission. The cadmium stearate-containing sample exhibits a marked reduction in the amount of Fraction II, while a barium-cadmium additive leaves the net amount of Fraction II relatively unchanged. It appears, therefore, that in the presence of cadmium, Fraction II is also reduced in quantity by crosslinking. 

To determine how a strong insolubility promoter like cadmium stearate, and a strong insolubility retarder like 2,6-di-ferf-butyl-4-methyl-phenol affects the resin when both are present, a series of one-hour oven-aging tests were run. The results are given in Table IV. Even at very low cadmium concentration the insolubilization effect is great and is only slightly altered by adding the hindered phenol. 

Table IV. Polymer Fraction in PVC Heated for One Hour in the Presence of Cadmium Stearate and 2,6-Di-terf-butyl-4-methylphenol...

Fig. 1 shows infrared RA and transmission spectra of seven-layer LB films of cadmium stearate on silver and ZnSe plates, respectively [11]. When one measures an infrared spectrum of a molecule with a long hydrocarbon chain such as cadmium stearate, one typically observes a number of infrared bands due to the... 

Fig. 2. Calculated tilt angles in an LB film of cadmium stearate. (Reproduced with permission from Ref. [11]. Copyright (1990) American Chemical Society.)...

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