Alkyl phosphonium

Dielectric relaxation studies of phosphorylated polyethers from — 180° to 200 °C have been used to study their structures. The magnitude of the dielectric constants of high-phosphonic-acid-content polymers is much larger than predicted, which suggests a microphase-separated structure. Conductance studies on some aryl- and alkyl-phosphonium salts showed a higher conductance for the halides than for the nitrate. ... 

The critical advantage of the quaternary phosphonium iodides is their excellent temperature stability. For example, the selected tetra(alkyl)phosphonium iodide salt, tri(n-octyl)(n-octadecyl) phosphonium iodide [(n-Oct)3(n-Octadecyl)P i, referred to as TOP18 ], shows no TGA weight loss up to 300°C. 

Table 1. Tetra(n-alkyl)phosphonium iodides tested.

Tetra(n-alkyl) phosphonium iodide Carbon Count M.W. M.P. (X) Solubility in Octane... 

A novel homogeneous process for the catalytic rearrangement of 3,4-epoxy-l-butene to 2,5-dihydrofuran has been successfully developed and scaled-up to production scale. A tri(n-alkyl)tin iodide and tetra-(n-alkyl)phosphonium iodide co-catalyst system was developed which met the many requirements for process operation. The production of a minor, non-volatile side product (oligomer) was the dominating factor in the design of catalysts. Liquid-liquid extraction provided the needed catalyst-oligomer separation process. 

By this method (Z)-monounsaturated fatty acids and esters could be obtained with an ( )-isomer content of less than 10% this stereoselectivity being however inferior to that of the commonly used acetylenic approach 55,56). However, the salt-free techniques used today in Wittig reactions allow (Z)-alkenoic acids to be synthesized with less than 2% of the ( )-isomers. Thus, Bestmann et al. prepared methyl and ethyl esters of (Z)-4,5,6,7,8,9,ll- and 13-alkenoic acids of different chain lengths 35,57 62), which served as intermediates in the synthesis of insect pheromones, both by reaction of co-alkoxycarbonyl-substituted alkyl-triphenyl-phosphonium salts with simple alkanals and of co-formylalkanoic esters with alkylidenephosphoranes. As the starting material for the synthesis of -substituted alkyl-phosphonium salts co-chloro- and -bromocarboxylic esters were used. The corresponding -substituted aldehydes can usually be obtained by ozone cleavage of suitable olefin derivatives or by oxidation of alkohols 57,58). 

Upon replacing the hydrated metal cation from the interlayers in the pristine layered silicates with organic cations such as an alkylammonium or an alkyl-phosphonium, the layered silicate attains a hydrophobic/organophillic character... 

The reactivity of 8b deserves specific attention. When treated with 2equiv of methyl triflate (in CDCI3), the / -(methylseleno)alkyl phosphonium triflate was obtained as a highly air-sensitive material in 76% yield (Scheme 10) <2002JA9706>. It is reasonable to assume that methyl triflate undergoes an electrophilic attack on the negatively charged selenium center of 8b, and this is followed by dissociation of the polarized Se-P bond (see Section 1.15.3). 

The primary, secondary and tertiary phosphines are weak bases, stronger, however, than the phosphine itself which is scarcely basic at all. The tetra-alkyl phosphonium hydroxides are strong bases. 

I-R1-3-R2 imidazolium N-alkyl pyridinium Tetra alkyl ammonium Tetra alkyl phosphonium... 

Enhancer for 1,2-dioxetane derivatives is composed of hydrophobic compound and fluorescent dye. We tested a variety of enhancers and found a better enhancer for this substrate, namely tetra-alkyl phosphonium derivative as hydrophobic... 

So far, the most frequently used onium salts are aryldiazonium, diaryl iodonium, triarylsulfonium, and tetra alkyl phosphonium salts with nonnucleophillic counter ion (Chart 11.1). 

A common group of cationic antistats is alkyl quaternary ammonium salts. These are mostly employed in polar substrates such as PVC and in styrenic polymers. Other types include alkyl phosphonium and alkyl sulfonium salts. Flexible PVC may contain up to 7% of these antistatics for nonfood uses, as they have not been approved by the FDA. Sodium alkyl sulfonates, similar to common detergents, have gained wide acceptance as anionic antistatic agents, and are used in PVC and styrenic polymers. Other anionic antistats include alkyl phosphonic, dithiocarba-mic, and carboxylic acids. 

The simplest and best established phosphonium salts are the tetra-alkyl phosphonium halides, R4P+ X". They are colourless salt-like solids with fairly high melting points which are soluble in water and stable to oxidation. ... 

Phosphonium salts are produced by acidification of an appropriate ylid (6.422) or by adding halophosphines or alkyl halides to ylids (6.377, 6.378). Phosphonium cations are obtained by reacting phosphorus pentachloride with phosphorus pentaphenyl (6.477) or with lithio biphenyl (480). Oxiranes react with phosphines to produce betaines which, in the presence of acids, give hydroxy-alkyl phosphonium salts (3.114). 

Alkyl phosphonium halides are decomposed by strong heating to give tertiary phosphines (6.32), whereas phosphonium hydroxides easily give phosphine oxide and hydrocarbon (6.109). The action of heat on triphenyl ((-alkoxycarbonyl alkyl) phosphonium salts is to produce ylids (6.391) (Section 6.10). 

Di-n-Cg to di-n-Cii alkyl phosphonium halides are the most effective ones, especially with regard to their activity against Pseudomonads. 

When a thermally stable organoclay treated with alkyl phosphonium is used [15], there is no reason to reduce the mechanical properties since no amorphous styrenics are added. Instead, there would be increasing tendencies of... 

The organoclays prepared were incorporated in LLDPE and LLDPE/LLDPE-g-MAH matrixes. Intercalated structures were obtained for uncompatibilized formulations based on Cloisite 20A and 2Ci8lm-MMT, whereas semi-exfoliated structures were reached for compatibilized formulations based on Cloisite 20A, 2Ci8lm-MMT and 3C4C16P-MMT. These results confirm the potential of alkyl imidazolium and alkyl phosphonium intercalants as adequate surface treatments for montmorillonite. Thermogravimetric measurements in oxidative atmosphere proved to be very sensitive to the dispersion state of the clay intercalated and semi-exfoliated nanocomposites exhibited significant increases in thermal stability ranging from -h13 C to -h37 C. 

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