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Topic: Hemiketal

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	Recovery of cyclohexanone from cyclohexylbenzene hydroperoxide acid cleavage product - Patent 4328372
		Apparently, at least one of a ketal and a hemiketal of cyclohexanone is formed by reaction of the alcohol during the acid catalyzed cleavage operation.
		It is a further object of the invention to generate cyclohexanone and alcohol from at least one of a ketal and a hemiketal which are present in the reaction mass obtained upon the acid catalyzed cleavage of cyclohexylbenzene hydroperoxide.
		In the presence of the acid catalyst, cyclohexanone (III) reacts with methanol to yield the dimethyl ketal of cyclohexanone (IV) and the methyl hemiketal of cyclohexanone (V).
	www.freepatentsonline.com /4328372.html (3216 words)

	Synthesis of Hemiacetals
		A hemiketal is an alcohol and ether attached to the same carbon, along with two other carbons.
		The ring structure is written with the orientation depicted on the left for the monosaccharide and is consistent with the way the glucose is depicted.
		The anomeric carbon is the center of a hemiketal functional group.
	www.elmhurst.edu /~chm/vchembook/704synhemiacetal.html (572 words)

	additionto CO (Site not responding. Last check: 2007-11-04)
		Hemiketal is the product of addition of alcohol to a ketone.
		A hemiacetal or a hemiketal can be further reacted with alcohols to convert them to acetals and ketals.
		The net structural change that occurs during this reaction is theat the OH group in a hemiacetal or a hemiketal is now replaced with a OR group.
	www.wiu.edu /users/mftkv/Chemistry102/addtocarbonyl.html (535 words)

	Rottnestol, a new hemiketal from the sponge Haliclona sp. (Site not responding. Last check: 2007-11-04)
		Rottnestol, a new hemiketal from the sponge Haliclona sp.
		Rottnestol, a new hemiketal, was isolated from an Australian collection of the marine sponge Haliclona sp.
		Hemiketal 3 was readily converted to its epimer, 4, and the methyl ketal of 4.
	home.ncifcrf.gov /mtdp/Catalog/abstract/abs273.html (78 words)

	BVDA America Inc.: Product information methylthioninhydrin
		We found that the hemiketal of 5-MTN with ethanol (see this pop-up window to see the chemical structure and the interrelation between the triketone, hydrate and hemiketal of 5-MTN) dissolves much faster than 5-MTN (ninhydrin) itself.
		The hemiketal, when applied to paper, will quickly react to the hydrate (the common form of a "ninhydrin") due to water present in the paper and in the atmosphere.
		The reaction between the amino acids in the fingerprint is therefore not adversely affected by using the hemiketal instead of the ninhydrin.
	usa.bvda.com /productinfo.php?file=methylthioninhydrin (1954 words)

	Learning Objectives for Chapter 6 (Site not responding. Last check: 2007-11-04)
		Recognize aldehydes, ketones, hemiacetals, acetals, hemiketals and ketals.
		Given a hemiacetal, acetal, hemiketal or ketal, show the aldehyde/ketone and alcohol from which it was formed.
		Given an bifunctional aldehyde or ketone, where alcohol is the second functional group, show the cyclic hemiacetal or cyclic hemiketal that would form.
	www.cord.edu /faculty/pmork/chem142/LearningChapter6.htm (174 words)

	Pressure Stabilization and Solvation Thermodynamics of a Hemiketal Reaction Intermediate
		This work reports the first pressure stabilization of a hemiketal intermediate, 2-methoxy-2 propanol, formed in the reaction of acetone and methanol, observed using Raman spectroscopy.
		Acetone dissolved in methanol is found to undergo a two-step reaction, with the ketal 2,2-dimethoxy-propane as the final product and the hemiketal observed as an intermediate.
		Comparisons with quantum calculations for the isolated reactant and product species are used to completely quantitate the effects of solvation on the hemiketal formation reaction.
	pubs.acs.org /cgi-bin/jtext?jpcafh/104/i49/abs/jp0028352 (182 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		It is assumed that C-2 "used to be" a D-hydroxyl before becoming a KETO group.
		The alpha anomer of a D-sugar is D (or down in Haworth projection) and the beta anomer of a D-sugar is L (or up in Haworth).
		a hemiacetal or hemiketal, is a "reducing" sugar.
	www.rci.rutgers.edu /~molbio/stryer/sugaruls.txt (280 words)

	HEMIACETAL
		Hemiacetals (and hemiketals) are addition products of alcohols to aldehydes and ketone respectively.
		The circled portion in the structures of hemiacetals and hemiketals are "essential structural features" that allows one to identify as well as distinguish a hemiacetal from a hemiketal.
		In fact, open chain hemiacetals and hemiketals are unstable and any attempts to isolate the will result in the decomposition of these compounds to give back the original carbonyl compound and the alcohol.
	www.wiu.edu /users/mftkv/Chem332/HEMIACETAL.html (468 words)

	Chapter 14
		With ketones, a hemiketal intermediate compound is produced which is then changed to a ketal (see Reaction 4.15).
		Cyclic hemiacetals and hemiketals are more stable than open-chain compounds and are important in sugar chemistry.
		Identify each of the following as a hemiacetal, hemiketal, acetal, ketal, or none of the above.
	www.earlycollegeadvantage.com /Tutor/chapter_14.htm (904 words)

	15 (Site not responding. Last check: 2007-11-04)
		If glucose forms a hemiacetal, it is called a pyranose because it has five carbons in the ring with oxygen.
		If fructose forms a hemiketal, a ring with four carbons results, which is called a furanose.
		If the reaction is, for example, between glucose and methanol, the product is one of two anomeric forms of glucoside acetals (Fig.
	nsm1.utdallas.edu /bio/DGray/Syllabi/Fall_03/3361GG07.htm (975 words)

	chap17 (Site not responding. Last check: 2007-11-04)
		Addition of one alcohol molecule to the carbonyl group of a ketone results in the formation of a hemiketal.
		The reaction of two alcohol groups with the Carbon of the carbonyl group in a ketone results in a ketal.
		If a ketone, it is either a hemiketal or a ketal.
	newark.osu.edu /jcabral/chem102/chap17.html (345 words)

	CM 123 March 9, 1998 Problem Set and Study Guide (Site not responding. Last check: 2007-11-04)
		Outline all the steps and discuss the driving force for the formation of the hemiketal of acetone and phenol from the rearrangement of the cumene hydroperoxide.
		Ketones in general form both hemiketals and ketals.
		Show all the steps in the acid catalyzed formation of the hemiketal from acetone and methanol.
	pages.poly.edu /~mgreen/march91.html (447 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		Like the addition of water, the carbonyl compounds are usually much more stable than the hemiacetals or hemiketals.
		The exception to this generalization occurs when the carbonyl and alcohol groups are in the same carbon chain and can react intramolecularly to form a 5 or 6 membered ring.
		The importance of this reaction is in the stability of the cyclic hemiacetal and hemiketal forms of carbohydrates.
	people.uis.edu /gtram1/organic/carbonyl/additionofalcohols.htm (332 words)

	Method for introduction of reporter groups into bacterial lipopolysaccharide-derived carbohydrates and the subsequent ...
		The method according to claim 1 or 2, wherein the keto-carboxy group of the polysaccharide is a part of a KDO (2-keto-3-deoxy-D-manno-octonic acid) monosaccharide unit of the polysaccharide.
		The method according to claim 26, wherein the presence of the antibody in the sample is diagnostic of the presence of Gram-negative bacteria in an animal from which the sample is derived.
		By using the hydrazide derivative of biotin, it was possible to react the PS directly with biotin-hydrazide without a prior oxidation step; the hydrazide was shown to react with the hemiketal of the reducing end KDO of the PS.
	www.freepatentsonline.com /6881549.html (17154 words)

	Carbohydrates - Cyclization of Monosaccarides (Site not responding. Last check: 2007-11-04)
		When a ketose cyclizes, the hydroxyl group on the second to last carbon undergoes an intramolecular reaction with the carbonyl group.
		The cyclization of fructose is shown below with the group characteristic of a hemiketal shown in red.
		See some additional detail on the cyclization reactions of carbohydrates or on hemiacetals and hemiketals.
	www.harpercollege.edu /tm-ps/chm/100/dgodambe/thedisk/carbo/yback3.htm (137 words)

	dec2.html (Site not responding. Last check: 2007-11-04)
		One of the reactions we left out the other day was the one between an hemiacetal or hemiketal with an alcohol.
		When we combine two sugars, the anomeric center of one of them will be blocked by formation of the glycosidic bond.
		Unless we used the hydroxyl from the hemiacetal or hemiketal of the other sugar (that is, the OH in C1') to form the glycosidic bond, the other sugar still has the possibility of opening into its linear form (hydrolysis of the hemiacetal/hemiketal):
	tonga.usip.edu /gmoyna/biochem341/lecture34.html (2729 words)

	Carbohydrate (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-11-04)
		A heterocyclic form of [[ribose (Haworth projection) ]] The straight-chain Structure described here is only one of the forms a monosaccharide may take.
		The aldehyde or ketone group may react with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, in which case there is an oxygen bridge between the two carbon atoms, forming a heterocyclic ring.
		Rings with five and six atoms are called furanose and pyranose forms, and exist in equilibrium with the straight-chain form.
	carbohydrate.iqnaut.net.cob-web.org:8888 (765 words)

	15N and 1H NMR Spectroscopy of the Catalytic Histidine in Chloromethyl Ketone-Inhibited Complexes of Serine Proteases
		The hemiketal hydroxyl groups in chloromethyl ketone (cmk) complexes of trypsin and chymotrypsin have been reported to ionize to the oxyanion with pK
		of ~7.5 must therefore be the hemiketal hydroxyl.
		We have used the behavior of this signal to directly confirm that His57 does not titrate in the trypsin and chymotrypsin complexes that were the subjects of the original
	pubs.acs.org /cgi-bin/abstract.cgi/bichaw/1996/35/i07/abs/bi9513968.html (280 words)

	Supplementary Carbohydrate Problems (Site not responding. Last check: 2007-11-04)
		Identify the structures in Questions 2 a,b and 3 a,b as a hemiacetal or hemiketal.
		Identify the conformational position of each OH and CH OH group as axial or equatorial.
		Identify the structures in Questions 7 a,b and 8 a,b as a hemiacetal or hemiketal.
	www.chem.csus.edu /jr/chem20/carbprob.html (152 words)

	Anomer - Wikipedia, the free encyclopedia
		In sugar chemistry, an anomer is a special type of epimer.
		It is a stereoisomer (diastereomer, more exactly) of a saccharide (in the cyclic form) that differs only in its configuration at the hemiacetal or hemiketal carbon, also called the anomeric carbon.
		If the anomeric carbon's hydroxy group is trans to the CH2OH group, then the sugar is an alpha anomer.
	en.wikipedia.org /wiki/Anomer (207 words)

	Carbohydrates
		Anomers are special types of epimers that occur after cyclization and reflect a change in configuration at the hemiacetal or hemiketal carbon.
		This carbon is also called the anomeric carbon, and the two variants are identified with an
		This creates a hemiacetal (from aldehydes) or a hemiketal (from ketones), resulting in an oxygen bridge between the two carbon atoms
	www.mcatpearls.com /master/node317.html (246 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations (Site not responding. Last check: 2007-11-04)
		Energy Citations Database (ECD) Document #5713015 - Evidence of hemiketals incorporated in the structure of fullerols derived from aqueous acid chemistry
		Availability information may be found in the Availability, Publisher, Research Organization, Resource Relation and/or Author (affiliation information) fields and/or via the "Full-text Availability" link.
		Evidence of hemiketals incorporated in the structure of fullerols derived from aqueous acid chemistry
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=5713015 (165 words)

	[No title]
		For this quiz, you must be able to do the following:
		CLASSIFY a given structure as a(n): aldehyde, ketone, hemiacetal, hemiketal, acetal, ketal
		], aldehyde, alkyl, alkene, alkyne, aromatic, carboxylic acid, cycloalkyl, disulfide, ether, halo [specific], hemiacetal, hemiketal, heterocyclic, ketal, ketone, thiol.
	www.mpcfaculty.net /ron_rinehart/30B/qz4guide.htm (223 words)

	Hemiketal RPG: Table of Contents (Site not responding. Last check: 2007-11-04)
		Table of Contents for the Hemiketal Weiss RPG
		Intro: Hemiketal is set immediately after the events of Kapital (first Weiss T.V. series), directly after the fall of the temple and the defeat of Estet.
		Weiss and Schwarz both survive--but they find them selves in an alien and baffling prison, where the rules don't seem to make sense, and there doesn't seem to be way out.
	home.earthlink.net /~hopeofdawn/tableofcontents.html (719 words)

	Model of Acetone Hemiketal and Ketal with methanol (via CobWeb/3.1 planetlab1.netlab.uky.edu) (Site not responding. Last check: 2007-11-04)
		Model of Acetone Hemiketal and Ketal with methanol (via CobWeb/3.1 planetlab1.netlab.uky.edu)
		In a similar fashion, alcohols will react in two steps with ketones, in the presence of an acid catalyst, to give a hemiketal (left) and a ketal (right).
		To rotate: press left mouse button on molecule and drag
	wps.prenhall.com.cob-web.org:8888 /wps/media/objects/725/743227/reacto5.html (68 words)

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