Determination of Hydroxy and Amino Compounds Using Pyromellitic Dianhydride

Siggia, Sidney.; Hanna, J. G.; Culmo, Robert

doi:10.1021/ac60175a027

Cited by 54 publications

(44 citation statements)

References 6 publications

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“…The similar intensity of the three signals (a) indicates that the polymer has a random distribution of the configurational sequences 18. The end hydroxyl groups were determined by the acetylation method19 to be predominantly secondary (more than 93%).…”

Section: Resultsmentioning

confidence: 99%

Controlled ring‐opening polymerization of propylene oxide catalyzed by double metal‐cyanide complex

Huang

Wang

2002

J. Polym. Sci. A Polym. Chem.

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A double metal‐cyanide catalyst based on Zn3[Co(CN)6]2 was prepared. This catalyst is very effective for the ring‐opening polymerization of propylene oxide. Polyether polyols of moderate molecular weight having low unsaturation (<0.015 meq/g) can be prepared under mild conditions. The molecular weight of polymer is entirely controlled by a reacted monomer‐to‐initiator ratio. The polymers prepared with stepwise addition of monomer exhibit a narrower molecular weight distribution as compared with those prepared with one‐step addition of monomer. Various compounds containing active hydrogen, except basic compounds and low‐carbon carboxylic acid, may be used as initiators. The reaction rate increases with increasing catalyst amount and decreases with rising initiator concentration. Polymerization involves a rapid exchange reaction between the active species and the dormant species. It was also proven that, to a certain extent, the chain termination of this catalytic system is reversible or temporary. 13C NMR analysis showed that the polymer has a random distribution of the configurational sequences and head‐to‐tail regiosequence. It is assumed that the polymerization proceeds via a cationic coordination mechanism. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1142–1150, 2002

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Section: Resultsmentioning

confidence: 99%

Controlled ring‐opening polymerization of propylene oxide catalyzed by double metal‐cyanide complex

Huang

Wang

2002

J. Polym. Sci. A Polym. Chem.

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“…To overcome the difficulties of using acetyl chloride solutions, 3,5-dinitrobenzoyl chloride can be used, and after hydrolysis, titration with tetrabutylammonium hydroxide (185) is carried out. Pyromellitic dianhydride has also been used as an acylating agent (186) in the presence of aldehydes. Colorimetric methods have been successfully used for determining trace amounts of ethanol.…”

Section: Methodsmentioning

confidence: 99%

Ethanol

Logsdon¹

2004

Kirk-Othmer Encyclopedia of Chemical Technology

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ETHANOL 1 a Refs. 6-14. b To convert kPa to atm, divide by 101.3. c To convert J to cal, divide by 4.184. d To convert C·m to debye, divide by 3.336 × 10 −30 (esu = D × 10 −18 ) .A summary of physical properties of ethyl alcohol is presented in Table 1. Detailed information on the vapor pressure, density, and viscosity of ethanol can be obtained from References 6-14. A listing of selected binary and ternary azeotropes of ethanol is compiled in Reference 15. Chemical PropertiesThe chemistry of ethyl alcohol is largely that of the hydroxyl group, namely, reactions of dehydration, dehydrogenation, oxidation, and esterification. The hydrogen atom of the hydroxyl group can be replaced by an active metal, such as sodium, potassium, and calcium, to form a metal ethoxide (ethylate) with the evolution of hydrogen gas (see Alkoxides, metal). 2 C 2 H 5 OH + 2 M −→ 2 C 2 H 5 OM + H 2 Sodium ethoxide [141-52-6] can be prepared by the reaction of absolute ethyl alcohol and sodium, or by refluxing absolute ethyl alcohol with anhydrous sodium hydroxide (16): CH 3 CH 2 OH + NaOH −→ CH 3 CH 2 ONa + H 2 O ETHANOL 3Commercially, water is removed by azeotropic distillation with benzene (17). Sodium ethoxide precipitates upon addition of anhydrous acetone (18). This strong base hydrolyzes readily to give ethyl alcohol and sodium and hydroxyl ions.Sodium ethoxide can also be prepared by the reaction of sodium amalgam with ethyl alcohol.Sodium ethoxide is used in organic synthesis as a condensing and reducing agent. The reaction between sodium ethoxide and sulfur monochloride yields diethyl thiosulfite (19).2 CH 3 CH 2 ONa + S 2 Cl 2 −→ (CH3CH2O) 2 S 2 + 2 NaCl Barbiturates (Veronal, Barbital, Luminal, Amytal), ethyl orthoformate, and other chemicals are produced commercially from sodium ethoxide.Aluminum and magnesium also react to form ethoxides, but the reaction must be catalyzed by amalgamating the metal (adding a small amount of mercury).6 CH 3 CH 2 OH + 2 Al −→ 2 (CH3CH2O) 3 Al + 3 H 2 2 CH 3 CH 2 OH + Mg −→ (CH3CH2O) 2 Mg + H 2 Well-cleaned aluminum filings react at room temperature in the presence of mercuric chloride (20, 21). In an autoclave, metallic aluminum and ethyl alcohol react without a catalyst at 120 • C (22). The reaction can also be promoted by the addition of sodium ethoxide (23). Aluminum should be avoided as a material of construction for ethanol service.Other reactions involving the hydrogen atom of the hydroxyl group in ethyl alcohol include the opening of epoxide rings to form hydroxy ethers, and the addition to acetylene [74-86-2] to form ethyl vinyl ether [104-92-2].These reactions are carried out in the presence of acidic and basic catalysts. The acid-catalyzed addition of ethyl alcohol to acetylene or to a vinyl ether produces acetals (diethers of 1,1-dihydroxyethane). The acid-catalyzed reaction of ethyl alcohol with an aldehyde or ketone also gives acetals.The hydroxyl group can be replaced by halogens from inorganic acid halides or phosphorus halides to give two different products, ethyl esters of the...

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“…and assume the first two reactions to be almost completed, only the third reaction is in progress after a sufficient period of time In Figure 2, the straight-line portion represents eq. (14). As before, the faster reactions are to be disregarded.…”

Section: Development Of the Methodsmentioning

confidence: 99%