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Topic: Ketal

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Hemiketal

Hemiacetal

Acetal

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	Ketal - Wikipedia, the free encyclopedia
		A ketal is a functional group or molecule containing the functional group of a carbon bonded to two -OAlkyl groups.
		Ketals and acetals can be used as carbonyl-protecting groups.
		Ketals and acetals can, under acid conditions, be converted back into a hemiacetal and an alcohol, as the entire reaction is an equilibrium.
	en.wikipedia.org /wiki/Ketal (218 words)

	Protection Strategies (Site not responding. Last check: 2007-11-06)
		To solve this problem one reacts the ketoester with a a 1,3-diol which leads to the conversion of the ketone into a cyclic ketal.
		Ketals are not attacked by nucleophiles and will therefore remain unaffected by LAH reduction of the ester.
		The ketone can be regenerated later on by treatment of the ketal with dilute acid.
	www.missouri.edu /~chemrg/bruice3e/chapter29/ketoester_ketal.html (90 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		The mole ratio of ketal or acetal or orthoesters to water may be 1-20:1, preferably 1.05-1.5:1, say 1.1:1.
		This signal turns on pump 18 which pumps the ketal, 2,2-dimethoxy propane from line 19, storage vessel 20, and line 22 through nozzles 23 into the mixing area 24 of sump 13.At this time, the 2,2-dimethoxy propane from nozzles 23 mixes with the liquid, containing water, in area 24.
		A signal is generated in sensor 16 which is passed through line 17; and this signal activates pump 18 which passes dimethoxy ketal through line 22 to nozzles 23.The mixed ketal and water is passed upwardly through acid resin catalyst bed 25 wherein the ketal reacts with the water to produce methanol and acetone.
	lawwww.cwru.edu /faculty/nard/ppl/patent_docs/4390417.doc (2225 words)

	Chem3D03 - Experiment #2
		The most common protecting group for aldehydes and ketones is the ethylene acetal or ketal (1,3-dioxolane derivative), which is easily prepared from the carbonyl compound and ethylene glycol in the presence of an acid catalyst.
		As you know, acetal/ketal formation is fully reversible under acidic conditions; the equilibrium is driven to the desired ketal by offsetting the equilibrium by removal of water using azeotropic distillation.
		The first step is protection of the ketone carbonyl as the ethylene ketal (1); the last step is an acid-catalysed dehydration which occurs during deprotection of the ketone.
	www.chemistry.mcmaster.ca /courses/3d03/old-labmanual/3d3ex2.html (862 words)

	Bio for Ketal
		Biography for Lieutenant JG Ketal, a Male Human/Vulcan aged 32, assigned to the Starbase Geneva
		Ketal is trim though by no means skinny and he has all the physical characteristics of his Vulcan ancestry.
		There is a slight scar on the back of his left hand and a small birthmark on his right shoulder.
	www.startrekfreedom.com /main/bios.php?bios=729 (488 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		Illustrative ketals may include: ##TBL1##Illustrative acetals may include: ##TBL2##Illustrative orthoesters may include: ##TBL3##The ketal, acetal, or orthoester cosolvent may typically be added in cosolvent amount of 10-1000 volumes, preferably 10-100 volumes, say about 55 volumes per 100 volumes of hydrocarbon fuel.
		The acid which catalyses the reaction of water with ketal or acetal or orthoester may be present in the various containers or conduits through which the composition passes or it may be present in water which is absorbed in the mixture as it stands or alternatively the mixtures may be contacted with acid.
		In the case of the solid zeolite or resin acids, it may be desirable to suspend bags or baskets of acid pellets in contact with the composition.
	lawwww.cwru.edu /faculty/nard/ppl/patent_docs/4395267.doc (1834 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		Ketals are often used as protecting groups in organic reactions.
		Ethyl acetoacetate reacts with ethylene glycol in the presence of acid to produce a ketal.
		The ketal can then be removed by acid catalysis hydrolysis, reversing the reaction that was used to form the ketal.
	people.uis.edu /gtram1/organic/carbonyl/additionofalcohols.htm (332 words)

	A formal synthesis of perhydrohistrionicotoxin
		The formation of the ketal 6 was regioselective due to the amide character of the dihydropyridone carbonyl, which disfavours the ketal formation.
		This result suggests that the vinyl triflate moiety of isomer 22 is hindered by the nearby ketal group and the tert-butyl group.
		On removing the BOC group, it is supposed that the conformational strain was released and the bulky groups moved away from the vinyl triflate so that the hydrogenation could occur.
	www.ch.ic.ac.uk /ectoc/echet96/papers/114/index.htm (1606 words)

	R. B. Woodward's Total Synthesis of Lysergic Acid - [www.rhodium.ws]
		Reaction of the epoxyalcohol 64 with methylaminoacetone ethylene ketal 15 gave, although poor yield, the desired amino glycol 67, which was very smoothly oxidized to the ketone 16 by slightly more than one mole of periodate in acid solution.
		The chloroform was distilled, and the epoxy ester was crystallized from an ethyl acetate-pet.
		A mix of 0.88g, (0.002mol) of 1-benzoyl-5-hydroxy-5-hydroxymethyl-4-[N-methyl-N-acetonylamino]-1,2,2a,3,4,5- hexahydrobenz-[cd]-indole ethylene ketal and 0.44g (0.0022mol) of sodium periodate in 10ml of water was treated with 0.2ml of concentrated sulfuric acid.
	www.erowid.org /archive/rhodium/chemistry/lysergic.acid.woodward.html (17875 words)

	Cyanohydrin process - Patent 4585590
		A mixture of 17.beta.-cyano-17.alpha.-hydroxyandrost-5-en-3-ethylidine ketal (IAb, Example 3, 3.57 g) in methylene chloride (10 ml) containing ethyl vinyl ether (2 ml) and pyridine hydrochloride (100 mg) is heated in a sealed bottle at 40.degree.
		Pyridinium hydrobromide perbromide (0.29 g) is added to 17.alpha.-(.alpha.-ethoxy ethyl)-ether-20-acetylaminopregna-5,20-dien-3-ethylidine ketal (VAb, Example 6, 411 mg) in a mixture of methylene chloride (3 ml), methanol (0.75 ml), water (0.12 ml) and triethylamine (0.26 ml) at 0.degree..
		A 2:1 mixture of 17.alpha.-(.alpha.-ethoxyethyl)-ether-20-trimethylacetylaminopregna-5,20-d iene 3-ethylidine ketal (VAb) and 17.alpha.-(.alpha.-ethoxyethyl)-ether-20-trimethylacetyl-aminopregn-5-ene 3-ethylidine ketal (IIIAb) is dissolved in toluene (5 ml) and THF (1 ml) and stirred with several mg of magnesium bromide under nitrogen at 20.degree.-25.degree..
	www.freepatentsonline.com /4585590.html (10129 words)

	JCE 2005 (82) 1057 [Jul] The Ethylene Ketal Protecting Group Revisited: The Synthesis of ...
		The multistep synthesis of 4-hydroxy-4,4-diphenyl-2-butanone from ethyl acetoacetate illustrates the use of a ketal protecting group.
		Reaction of ethyl acetoacetate with ethylene glycol with p-TsOH in toluene produced the ketal ester.
		Reaction of the crude ketal ester with two equivalents of phenyl magnesium bromide followed by an aqueous acid workup generated the tertiary alcohol and simultaneously removed the ketal protecting group to produce the hydroxyketone.
	jchemed.chem.wisc.edu:8000 /Journal/issues/2005/Jul/abs1057.html (380 words)

	The Daily Star Web Edition Vol. 5 Num 449 (Site not responding. Last check: 2007-11-06)
		Jamaatul Mujahidin (JMB) raised its armed outfit in the name of "Ketal Bahini" in border areas of Satkhira district, recruited youths and trained them to fight to establish Islamic rule in the country.
		This was gathered by this correspondent during a visit to Banshdah and Satani border villages on Saturday.
		They said the Ketal Bahini was raised to fight to establish Islamic rule.
	www.thedailystar.net /2005/08/30/d50830070169.htm (722 words)

	Ciba Specialty, Dorf Ketal sign distribution pact
		Mumbai, Feb 11: CIBA Specialty Chemicals (India) and Dorf Ketal Chemicals India have signed a co-operation agreement, wherein the latter will become an exclusive distributor for Ciba Additives to the process chemicals industry.
		Ciba (India) vice-president GS Kohli said, "The co-operation in distribution will combine Dorf Ketal Chemicals' marketing know-how and Ciba's technology expertise to provide the process chemical industry with integrated solutions, high performance products and technical support".
		Dorf Ketal, which has several single source supply contracts or alliances with its customers, has a manufacturing and research facility at Taloja.
	www.expressindia.com /fe/daily/19990212/fco12004.html (267 words)

	Zercher group web page (Site not responding. Last check: 2007-11-06)
		We are particularly interested in substrates in which an a-diazo-b-keto ester or an a-diazo ketone functionality is tethered to a functionalized ketal.
		A variety of rearrangement pathways are available to the ylide, although the substitution pattern of the ketal is the major determining feature.
		Rearrangement of the bicyclic ketal skeleton into a spirolactone provides an attractive entry into the hyperolactone family of natural products.
	www.unh.edu /chemistry/ckz/index.htm (735 words)

	Recent progress in electron-beam resists for advanced mask-making
		These ketal resist systems, or KRSs, have undergone a series of optimization and evaluation cycles in order to fine-tune their performance for advanced mask-fabrication applications using the 75-kV IBM EL4+ vector scan e-beam exposure system.
		The ketal protecting group is derived from a carefully selected enol ether to which the phenolic hydroxyl is added under acidic conditions (Scheme VI).
		This germanium-containing polymer, containing ~5 wt% Ge, was then successfully protected with a ketal protecting group to afford an imageable CA polymer matrix.
	www.research.ibm.com /journal/rd/455/medeiros.html (3991 words)

	Diversified Industries Ships First U.S. Order of DVS 6000 to Dorf Ketal : ArriveNet Press Releases : Industry (Site not responding. Last check: 2007-11-06)
		Houston-based Dorf Ketal has ordered 13, 45-gallon drums of DVS 6000 after putting it through a series of lab and field tests.
		A proprietary product developed by Diversified Industries, DVS 6000 is a proven non-toxic hydrogen sulphide (H2S) scavenger that has a variety of applications for the oil and gas industry and related industrial sectors.
		The first U.S. order follows the recent completion of a field trial by Dorf Ketal in which DVS 6000 effectively eliminated odours associated with light-end mercaptans contaminating a gasoline/diesel fuel mixture in a tanker truck.
	press.arrivenet.com /industry/article.php/410576.html (578 words)

	BENZILDIMETHYL KETAL (2,2-DIETHOXY-2-PHENYLACETOPHENONE)
		Photoinitiators are compounds that break down into free radicals upon exposure to ultraviolet radiation.
		Photoinitiators undergo a unimolecular bond cleavage upon irradiation to yield free radicals (benzoin esters; benzil ketals; alpha-dialkoxy acetophenones; alpha-hydroxy-alkylphenones; alpha-amino alkyl- phosphine; acylphosphine oxides).
		Another type of photoinitiators undergo a bimolecular reaction where the excited state of the photoinitiator interacts with a second molecule (a coinitiator) to generate free radicals(benzo phenones,amines; thioxanthones,amines; titanocenes).
	www.chemicalland21.com /specialtychem/finechem/BDK.htm (192 words)

	Formal Synthesis of (+)- and (-)-Perhydrohistrionicotoxin: A "Double Henry"/Enzymatic Desymmetrization Route to the ... (Site not responding. Last check: 2007-11-06)
		Deoxygenation of 12 using a Barton protocol, followed by Zemplén deacylation and Swern oxidation, gave the (-)-antipode of the Kishi lactam (3).
		Moffatt oxidation of hydroxyacetate 12 followed by ketal protection and Zemplén deacylation gave ketalalcohol 19.
		Barton deoxygenation of 19 followed by ketal hydrolysis gave (+)-3.
	pubs.acs.org /cgi-bin/jtext?joceah/64/i15/abs/jo990293i (203 words)

	C251.03 Lab -- Frontalin Project (Site not responding. Last check: 2007-11-06)
		Notice that you are using a Dean-Stark trap again, this time the Dean-Stark trap is used to remove water from the reaction as it proceeds, thus driving the equilibrium toward the desired ketal.
		In another system, containing both ketal and TBDMS protecting groups, I was able to remove them both by heating at 60 °C for 5 hours in 80% acetic acid/water.
		Under these conditions the ketal protecting group was removed quickly (in about an hour) but the TBDMS group (in the case I was looking at it was a secondary alcohol) took longer.
	www.ups.edu /faculty/hanson/c251lab.03/frontalin/frontalin.htm (4052 words)

	Index-Dorf Ketal
		Dorf Ketal offers Chemtreat's advanced patented polymer technology, which works under stressed conditions in cooling water and boiler water systems.
		Dorf Ketal has an advanced laboratory at Taloja manned by a group of technical and analytical personnel who can provide support for your routine as well as non routine activities.
		Dorf Ketal specialty chemicals and services relate to all phases of internal treatment for re-circulating, cooling, closed and once through systems.
	www.dorfketal.com /wtcdivision.htm (349 words)

	houston ketal ultrasound pictures ► Ultrasound: Parts, Service, Training (via CobWeb/3.1 planetlab1.isi.jhu.edu) (Site not responding. Last check: 2007-11-06)
		houston ketal ultrasound pictures is celebrated and abored on this website and throughout the known world.
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	www.yltrasound.ultasound.net.cob-web.org:8888 /houstonketalultrasoundpictures.html (323 words)

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	www.ketal.ru (102 words)

	PLCS.net - Interactive Q & A - RTU´s
		I guess Ketal asked the question in the correct manner, because both of those answers were excellent.
		I wish I could remember this stuff that well.
		Seriously, Ketal, the objective is to have a new generation coming up to carry us old farts when we start to fall down!
	www.plctalk.net /qanda/showthread.php?t=1553 (1015 words)

	Tri-Iso, Inc. - UOP (Site not responding. Last check: 2007-11-06)
		Dorf Ketal recently acquired UOP's interest in the Unilink® and Clearlink® diamine product lines.
		Many of the technical papers listed below were originally issued by UOP.
		Slide Presentation: "Evaluating a Secondary Aliphatic Diamine Curative"
	www.tri-iso.com /products/dorf_ketal.html (154 words)

	houston 3d ketal ultrasound ► Ultrasound:75% off OEM pricing. Free tech support. Call Now. (via CobWeb/3.1 ... (Site not responding. Last check: 2007-11-06)
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	www.ultraoundmachines.ultfasound.us.cob-web.org:8888 /houston3dketalultrasound.html (138 words)

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	community.webshots.com /album/402091135hzHxuG (292 words)

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	www.linkedin.com /pub/0/621/a88 (31 words)

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