- Synthesis of acyclic quaternary ammonium compounds containing ω-alkoxyethyl and 2-hydroxyethyl substituents at the nitrogen atom
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A series of acyclic symmetric quaternary ammonium chlorides Me2(HOCH2CH2)N+(CH2CH2O)nR Cl– (n = 1, R = n-C9H19; n = 2, R = n-C6H13; n = 3, R = n-C3H7) was synthesized by alkylation of the corresponding tertiary amines Me2N(CH2CH2O)nR with ethylene chlorohydrin in a two-phase system, using water as a solvent. The tertiary amines were synthesized in a heterogeneous system organic phase—aqueous phase, using an aqueous solution of Me2NH and a solid alkali. The intermediate monoethers of ethylene, diand triethylene glycol were obtained in high yield via a phase-transfer alkylation in dioxane, using solid KOH. The proton and carbon atom signals in the NMR spectra of the synthesized amines and ammonium chlorides were assigned based on the data of heteronuclear correlations (1H, 13C).
- Tcarkova,Belus’,Artyushin,Kharlamov,Bondarenko
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- Combinatorial synthesis of PEG oligomer libraries
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A simple chain-extending approach was established for the scale-up of the monoprotected monodisperse PEG diol materials. Reactions of THP-(OCH2CH2)n—OMs (n=4, 8, 12) with a large excess of commercially available H—(OCH2CH2)n—OH (n=1-4) under basic conditions led to THP-(OCH2CH2)n—OH (n=5-15). Similarly, Me-(OCH2CH2)n—OH (n=4-11, 13) were prepared from Me-(OCH2CH2)n—OMs (n=3, 7, 11). For the chain elongation steps, 40-80% yields were achieved through extraction purification. PEG oligomer libraries I and II were generated in 50-95% overall yields by alkylation or acylation of THP-(OCH2CH2)n—OH (n=1-15) followed by deprotection. Alkylation of Me-(OCH2CH2)n—OH (n=1-11, 13) with X—(CH2)m—CO2R (X=Br or OMs) and subsequent hydrolysis led to PEG oligomer library III in 30-60% overall yields. Combinatorial purification techniques were adapted to the larger-scale library synthesis. A total of 498 compounds, each with a weight of 2-5 g and a minimum purity of 90%, were synthesized.
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Page/Page column 9
(2010/02/15)
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- Topical mosquito repellents VII: Alkyl triethylene glycol monoethers
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Normal and branched chain aliphatic monoethers of triethylene glycol are effective topical mosquito repellents. In terms of duration of protection, they are generally superior to the corresponding diethylene glycol analogs, and some are superior to diethyltoluamide. The n heptyl monoether of triethylene glycol affords double the protection time of diethyltoluamide under controlled laboratory conditions, and appears to be a useful new mosquito repellent.
- Johnson,DeGraw,Engstrom,Skinner,Brown,Skidmore,Maibach
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p. 693 - 695
(2007/10/05)
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