Document nmaYZM38Dzkj6QEr94xObrRXa
AR226-3355
PHYSICOCHEMICAL PROPERTIES Or FLUOROTELOMER ALCOHOLS
M ary A Kaiser
ttryi P Cabranchi,3 Chien-Ping Chai K a o / Pan! J. KrtiSic.1Alexander A. Marchiane, ' Robert L. Wateriond * and Robert C. Back 3
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Abstract
Physicochemical properties such as vapor pressure and water 1 solubility a r e necessary to d eterm ine environmental transp ort potential and environmental f a t e O fte n th e s e p rop erties are estim ated from models based an properties o f chem ically similar i materials. Fluorinated compounds, however, are especially d iffic u lt to model since th e properties o f fluorinated compounds j are quite d iffe re n t from their hydrocarbon analogues. Fluorotelom er Alcohols a r e also d iffic u lt to obtain in pure fo rm sin ce t h e y a re 'p rod u cts by p rocess' which a r e a m ixture o f several compounds each d iffe rin g by two carbon u nits and d iffic u lt to measure since many a r e solids a t room tem perature.
Introduction
The environmental f a t e o f perfiu onnated chemicals, such as fluorotelom er-based substances is o f growing interest.1-4 Fluorotelomer Alcohols, including 8 -2 Telomer B alcohol, C F s C C F ^ H a C K -O H , used in th e manufacture o f fluorinated surfactants and fluorinated polymers. These substances provide unique s u rfa c e modification properties in a wide variety o f consumer products. Fluorotelomer Alcohols are o f particular interest since they are expected to b e amor# th e possible compounds into which fluorotelom er-based su rfa cta n ts and polymers may potentially transform in th e environment.
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Vapor P ressu re Three techniques were used to measure th e vapor pressure.
VP Method 1 (refO 'Sh ee 8)
- based on a dynamic measurement procedure developed by Sco tt
- equilibrium temperature measured at a controlled pressure.
- temperature varied from 80 to 200 C.
- approximately 30 g o f th e 8 -2 Telomer B alcohol were placed in a boiler. The pressure was held constant to 0.01% {0.01 kPa) and measured to an accuracy o f 0.01 %.
- Apparatus Mensor PCS400 presstre controller (San Marcos, TX) Parascientlfie 740 pressire transducer (Redmond. WA) Hart Scientific stack base unit for temperature measurement (Americm Fork, UT).
VP M ethod Z (reference 9)
- based on th e EPA OPPTS gas saturation m ethod (used to obtain the vapor p ressu re o f 8 -2 Telomer 0 Alcohol a t room temperature)
- quantity o f a sub stance transported by a known volume o f a carrier gas is determined.
- alcohol placed in a gloss therm os ta te d tube. G asc hromatogrephic grad e helium (99.999%) flow ed over t h e solid 8-2 Telomer B alcohol.
- flow controller from a H ew lett Packard (now A gilent. Little Falls, DE) model 58 90 gas chromatograph
- Due to th e adsorptive properties o f th e alcohol, th e vapor pressure was calculated from w eight loss r a th er than fro m th e weight o f trapped material downstream
- vapor pressure is calculated from th e vapor density, W /V. by means o f th e equation P /Pa = W /V RTZtA,. where P is th e vapor pressure in Pa. W is th e mass o f transp orted substance in gram s, V is t h e volume o f satu rated g a s in cubic m eters, R is th e universal molar gas constant, T is th e tem perature In K, and M r is th e relative molecular mass
- vapor p ressu re a t 21 C was 3 Pa
VP Method 3 (r e fe r e n c e s 10J l )
gas phase nuclear magnetic resonance
method measures the vapor density a t various temperatures relative to th at o f a much more volatile internal mass standard present in much smaller molar amounts o f die order o f 1 mol %
vapor density is converted to vapor pressure using the ideal gas law or another appropriate equation o f stote.
Solubility methods 1 and 2
GC/ECti and GC/MSD determination o f analyte in a closed, sealed, shaken container in the presence of excess sample
Proton and Fluorine 6 a s rPhase N M R S p e c tra ,
o f 8 -2 T e lo m e r B Alcohol a t D if f e r e n t
Tem peratures
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Comparison o f Literature Vapor Pressures of H ex a f iuorobenzene with Vapor Pressures Obtained by Gas-Phase NM R with Least-Squares F its Based on the
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Vapor Pressure o f 8 - 2 Telomer 8 alcohol by th e Boiler Method with Le a s t Squares f i t using Antoine Equation. Also shovwi. Vapor Pressure a t 21 " C by Gas Saturation Method
Vapor Pressure o f Se le ct Telomer Alcohols b y Sas-Phase NM R Spectroscopy
Comparison with o th er methods
Koa vs poL fo r Perfluoroalkylated Substances
Ab-initio Calculation of AEibond
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: Conclusions: 1. The cyclic structure b has 0 weak H-bond. 2. There would be no significant change Inthe vaporpressure of the fluorotelomer alcohols dueto bonding o f type (b).
Results & Discussions
Vapor P ressure. T h e vapor pressure o f th e 8 -2 Telom er 8 Alcohol varies fr o m 3 Pa a t 21 C to 101 kPa a t 201 C .
- a least-squares f i t o f the data, including th e low temperature measurement by th e gas saturation method, was obtained using th e Antoine equation
log,o (P/kRa) = a - b/(c + 1/ C) (Figure 2) with th e parameters a = 6.457, b = 1623, and c = 163.3
- boiling point o f 20L3 C was extracted (vepor p ressire at IOL325kPa)
- excluding th e gas saturation value from th e d a ta to be fitted has no e f fe c t on th e resulting Antoine parameters (as might be expected since it is several orders o f magnitude smaller than the boiler data a t substantially higher temperatures).
W a ter Solubility. The solubility in w ater a t 12 C is 134 ppb ( 29 ppb)(134 g/L); 137 ppb ( 53 ppb) a t 25 C: 318 ppb ( 176 ppb) at 37 C . and 225 ppb ( 51 ppb) a t 60 C. Varying pH from 3 to 11 hod little or m impact on the solubility measurement.
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