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	KETENES - LoveToKnow Article on KETENES
		Two classes may be distinguished: the aldo-ketenes, including ketene itself, together with its mono-alkyl derivatives and carbon suboxide, and the keto-ketenes which.comprise the dialkyl ketenes.
		The ketenes are usually obtained by the action of zinc on ethereal or ethyl acetate solutions of halogen substituted acid chlorides or bromides.
		Diphenyl ketene, (C,H6)2C :CO, obtained by the action of zinc on diphenyl-chloracetyl chloride, is an orangered liquid which boils at 146 C. (12 mm.).
	www.1911encyclopedia.org /K/KE/KETENES.htm (352 words)

	Middle East Institute: Policy Brief
		Ketene then summarized the current situation through an analysis of three major points: the misunderstanding of the American administration of northern Iraq, Kurdish oppression, and the city of Kirkuk.
		Ketene asserts that after the second Gulf War, the Kurds expanded their area of influence because the Americans viewed the Kurds as their strategic ally.
		Ketene avers that Kurds are monopolizing the government offices in Kirkuk, hence, all decisions have been made in favor of the Kurds.
	www.mideasti.org /articles/doc194.html (765 words)

	Sizing method and sizing composition for use therein - Patent 4478682
		Thus, phenyl ketene dimer is: ##STR1## benzyl ketene dimer: ##STR2## and decyl ketene dimer is (C.sub.10 H.sub.21 --CH.dbd.C.dbd.O).sub.2.
		An emulsion of a ketene dimer prepared from a mixture of palmitic and stearic acids was prepared by admixing 880 parts of water, 60 parts of cationic corn starch and 10 parts of sodium lignin sulfonate.
		The use of this nitrogen-containing resin as an accelerator for ketene dimers is disclosed in New Zealand Pat.
	www.freepatentsonline.com /4478682.html (4910 words)

	United States Patent Application: 0040215033
		In JP-A 62-87594, a silyl ketene acetal is obtained in a highly pure form (.gtoreq.95%) by using rhodium trichloride trihydrate as the catalyst and an excess amount of hydrosilane and converting the carbonyl adduct to a high-boiling compound.
		However, by this process, it was difficult to obtain silyl ketene acetals in high yields because of the decreased yields based on the hydrosilane used, and of the increased distillation residue leading to lower isolated yields.
		[0072] In the preparation of disilyl ketene acetals according to the third embodiment of the invention, the compound of formula (6) is reacted with the compound of formula (2) in the presence of a catalytic amount of tris(pentafluorophenyl)borane.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040215033".PGNR.&OS=DN/20040215033&RS=DN/20040215033 (5546 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		The ketene route is based on the catalyzed thermal dehydration of acetic acid to ketene, and the subsequent reaction of the ketene with more acetic acid to form acetic anhydride.
		The ketene process is characterized by high selectivity in the conversion of acetic acid to ketene (90 percent) and in the conversion of ketene to acetic anhydride (100 percent).
		The gaseous ketene is removed from the heavier boiling acetic anhydride, acetic acid, and water in a system of graduated coolers.
	www.chemsystems.com /newsletters/perp/Jun04_N03S1.cfm (1881 words)

	Reaction of ketene and [dimethyl(phenyl)silyl]ketene with the aminoxyl radical TEMPO: Preparative, kinetic, and ... (Site not responding. Last check: 2007-11-04)
		Ketene (1) is found to be much less reactive than the ketenes 15a-d,f,g (Table 2), all of which possess conjugating substituents which are expected to stabilize an intermediate from TEMPO addition to 1-C, which would have radical character on 2-C, as shown for 4 (Scheme 2).
		Ketene is also less reactive by a factor of 39 towards TEMPO than is cyclopentylidenemethanone 16, in which the radical intermediate is stabilized by two alkyl groups.
		In conclusion computational studies predict a strong preference for reactions of aminoxyl radicals with ketene at 1-C as compared to addition to 2-C, a preference that may be explained as due to the formation the stabilized ester function.
	www.arkat-usa.org /ark/journal/2002/I12_Muchowski/JM-597F/597F.asp (2965 words)

	Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs)
		For this draft technical standard, therefore, the respirators have been selected on the basis of the assigned protection factor afforded by each device up to 50 ´ the OSHA PEL of 0.5 ppm (i.e., 25 ppm); only the "most protective" respirators are permitted for use in concentrations exceeding 25 ppm.
		Basis for revised IDLH: The revised IDLH for ketene is 5 ppm based on acute inhalation toxicity data in humans [Stokinger 1960] and animals [Treon et al.
		Physiologic response of animals exposed to airborne ketene.
	www.cdc.gov /niosh/idlh/463514.html (221 words)

	Paperloop.com - leading the pulp, paper, packaging and printing industry (Site not responding. Last check: 2007-11-04)
		A commercial liquid ketene dimer made from a mixture of oleic and linoleic acids was used for the evaluation.2,3 Ketene dimer addition level was varied from 0.100% to 0.175%.
		A cationic starch based emulsion of a ketene dimer made from a mixture of palmitic and stearic acids (AKD) was used for the evaluation.1,5 Addition sequence 3 was chosen as the most difficult test of sizing efficiency (Table 1).
		Both bound and unbound ketene dimer are known to contribute to sizing.7,8 PCC affects sizing by reducing ketene dimer retention.
	www.paperloop.com /db_area/archive/p_p_mag/2001/0006/wet-end.htm (1877 words)

	Abstract of CEH report Ketene/Diketene (Site not responding. Last check: 2007-11-04)
		Ketene and diketene are important industrial intermediates generally used at their production sites.
		Ketene is a colorless, highly reactive gas that is irritating to the lungs.
		The major use for ketene is the manufacture of acetic anhydride and diketene.
	www.sriconsulting.com /CEH/Public/Reports/669.5000/Abstract.html (248 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		Ketene and the ketyl radical have been reported as important intermediates in the oxidation of hydrocarbons and related compounds (1), and specifically in the oxidation of methane (2), acetylene (3), and acetone (4).
		It is difficult to simulate the rapid, autocatalytic overall rate of reaction for ketene autoxidation, without having an unusually fast rate for the addition of hydroperoxyl to ketene.
		This is consistent with recent work (11) on the epoxidation of acrolein by peracetyl radicals, which demonstrated that having a carbonyl group in the vicinity of a C-C double bond greatly increases the rate of addition of peroxyl radicals, when compared with unsubstituted alkenes.
	www.york.ac.uk /res/gkg/ketene_poster/ketene_p (386 words)

	US to Divide Kirkuk Parliament Equally (Site not responding. Last check: 2007-11-04)
		Ketene pointed out that they were aware that the Provincial Election Council was controlled completely by the Kurdish and they would not have the result they desired; however, a boycott would create a less favourable result, expressed Ketene.
		Evaluating the Iraqi election to Zaman Ketene went on to say that nearly 200,000 of 430,000 electors expected to vote in Kerkuk where 860,000 people live consisted of Turkmen.
		Ketene concluded that the US Kerkuk Consul warned them during a visit that they would end up being the loser if theyboycotted the elections.
	www.aina.org /news/20050129151118.htm (199 words)

	Nat' Academies Press, Biographical Memoirs V.54 (1983) (Site not responding. Last check: 2007-11-04)
		I I. McEIvain's interest in ketene acetal was originally aroused by a proposal in the literature that I, I-diethoxyethylene, the diethylacetal of ketene, is an intermediate in the above- mentioned CIaisen self-condensation of ethyl acetate.
		The reaction of ketene diethylacetal with a,,8-unsaturated carbonyl compounds.
		Cyclic trimerization of ketene diethylacetal by hydrogen fluoride: 1,1,3,3,5,5,- hexaethoxycyclohexane.
	www.nap.edu /books/0309033918/html/220.html (3187 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		Such ketene complexes are well known key intermediates in the catalytic conversion to organic molecules.
		Transition metal ketene complexes are important intermediates in catalysis such as the Fischer-Tropsch process, which involves catalytic CO activation and carbon-carbon coupling chemistry.
		The objectives of this original research are; 1) to develop new methods to prepare organic ketenes, 2) to study the ligand effects on the bonding modes of late transition metal ketene complexes.
	www2.semo.edu /ritter/gong/RESPAGE.HTM (1497 words)

	The Gas-Phase Autoxidation of Ketene (Site not responding. Last check: 2007-11-04)
		In the simulations, radical chain branching is by the decomposition of methylhydroperoxide (observed as a product at 603 K), with the methyl radicals formed predominantly by addition of hydroxyl (9) and hydroperoxyl (10) radicals to the alpha-carbon, followed by an internal hydrogen transfer reaction.
		OH + CH It is difficult to simulate the rapid, autocatalytic overall rate of reaction for ketene autoxidation without having an unusually fast rate for the addition of hydroperoxyl to ketene.
		This is consistent with recent work (11) on the epoxidation of acrolein by peracetyl radicals, which demonstrated that having a carbonyl group in the vicinity of a C=C double bond greatly increases the rate of addition of peroxyl radicals, when compared with unsubstituted alkenes.
	www.york.ac.uk /res/gkg/ketene_poster/prel_abs.html (409 words)

	ketene -- Encyclopædia Britannica
		any of a class of organic compounds containing the functional grouping C=C=O; the most important member of the class being ketene itself, CH =C=O, which is used in the manufacture of acetic anhydride and other industrial organic chemicals.
		The name suggests that ketenes are unsaturated ketones, but their chemistry resembles that of carboxylic acid anhydrides.
		"ketene." Encyclopædia Britannica from Encyclopædia Britannica Premium Service.
	www.britannica.com /eb/article-9045195?tocId=9045195 (63 words)

	Code of Federal Regulations: 21 CFR 176 INDIRECT FOOD ADDITIVES: PAPER AND PAPERBOARD COMPONENTS
		Alkyl ketene dimers may be safely used as a component of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food, subject to the provisions of this section.
		(a) The alkyl ketene dimers are manufactured by the dehydrohalogenation of the acyl halides derived from the fatty acids of animal or vegetable fats and oils.
		(b) The alkyl ketene dimers are used as an adjuvant in the manufacture of paper and paperboard under such conditions that the alkyl ketene dimers and their hydrolysis products dialkyl ketones do not exceed 0.4 percent by weight of the paper or paperboard.
	vm.cfsan.fda.gov /~lrd/fcf176.html (9763 words)

	LBL Researchers study Ketene Chemical Transition (Site not responding. Last check: 2007-11-04)
		Using a technique called photofragment spectroscopy, the team was able, for the first time, to directly observe transition state quantum energy levels in a unimolecular reaction -- one involving only one molecule as the reactant -- and deduce the molecular motions associated with them.
		The chemists began their study by cooling a sample of ketene molecules in a supersonic jet expansion to near absolute zero temperatures in order to ensure that all of the molecules started out at the same energy.
		Data from this experiment also verified some, but not all, of the theoretical predictions made for the intermediate structures assumed by ketene in the transition state.
	www.lbl.gov /Science-Articles/Archive/ketene-chemical-transition.html (678 words)

	Transition State Chemistry Discovery at LBL (Site not responding. Last check: 2007-11-04)
		The schematic depicts the dissociation of ketene (CH2CO), showing how the rate of reaction increases in a stepwise manner as the total energy increases through transition state vibrational thresholds (white lines), and how motions (fl arrows) at the transition state carry through to products.
		The tests were conducted on ketene (CH2CO), a reactive gas that absorbs energy from ultraviolet photons and separates into CH2 and CO. A sample of ketene molecules was chilled to nearly absolute zero in order to ensure that all of the molecules started out at the same energy.
		Ultraviolet laser light was then flashed on the molecules to cause the reaction breaking the C-C bond and separating the CH2 and the CO fragments of ketene.
	www.lbl.gov /Science-Articles/Research-Review/Highlights/1993/transition-state-chemistry.html (492 words)

	Pulp & Paper: Studies indicates wet-end additive effects on AKD retention, reaction efficiency
		Outlines of the addition sequences that were used are shown in Table 1.The sizing performance of addition sequence 1-PCC (12.0%), followed by cationic starch (0.5%), ketene dimer, and alum (0.2%)-was chosen as a baseline for determining the effects of moving PCC and ketene dimer addition points.
		Moving the PCC addition point closer to the fan pump, however, had a large, negative effect on ketene dimer efficiency (compare sizing results for sequences I and 3).
		Handsheets for retention testing were made in a dynamic handsheet mold ()HM)4 under high shear conditions over a wide range of ketene dimer (0.075% to 0.150%), PCC (10% to 20%), wet-end cationic starch (0% to 1%), alum (0% to 0.5%), and anionic polyacrylamide retention aid (0.01% to 0.05%,APAM) addition levels.
	www.findarticles.com /p/articles/mi_qa3636/is_200106/ai_n8980306 (1449 words)

	BuzzFlash World Media Watch, February 26, 2003 (Site not responding. Last check: 2007-11-04)
		Speaking at a meeting of the Assembly of Turkish-American Associations on Tuesday, Ketene evaluated history and future of Turkmen living in Northern Iraq.
		Stating that it was planned that Shi'ite Kurdish civilians who had been expelled by Saddam Hussein to Iran would rush to oil cities Kirkuk and Mousul after Saddam regime, Ketene said that this 100 thousand-people group including women and children who were known as ''vagabonds'' was being kept in camps.
		Defending that those cities' demographic structure that was formed mainly by Turkmens was planned to be replaced with people who had fake documents, Ketene said the U.S. army could not stop civilians so Turkish troops should exist in the region.
	www.buzzflash.org /mediawatch/03/02/26.html (1509 words)

	Toxicologic Review of Selected Chemicals
		This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.
		Ketene is highly irritating to the respiratory tract (Mendenhall and Stokinger 1959/Ex.
		The Agency concludes that workers exposed to this highly irritating and toxic gas are at significant risk of developing respiratory irritation, pulmonary edema, and other severe pulmonary effects that constitute material health impairments.
	www.bu.edu /ehs/ih/tox/463-51.htm (325 words)

	Carbonless.org (Site not responding. Last check: 2007-11-04)
		Use of the optional hydrophobic hydrocarbon sizing agents (viz., component (c) above) permits a reduction in the amount of components (a) and (b) employed and a reduction in the total cost of the sizing treatment composition.
		Preferred hydrophobic hydrocarbon sizing agents are cellulose-reactive materials and include (a) alkyl ketene dimers, (b) octadecyl isocyanates, (c) alkenyl succinic anhydrides, and (d) rosin acid anhydrides.
		Alkyl ketene dimers are most preferred for use in the sizing treatment compositions of this invention.
	www.carbonless.org /patents_4426466.htm (1727 words)

	Publisher description for Library of Congress control number 94007884 (Site not responding. Last check: 2007-11-04)
		Before the publication of this book, chemists looking for an introductory survey of ketene chemistry found themselves facing a serious problem: such works were either out-of-date or uneven in their coverage, or both.
		With the publication of Ketenes, Thomas Tidwell has succeeded in producing a truly comprehensive, up-to-date introduction to the entire field of ketene chemistry.
		Not since Hermann Staudinger, the discoverer of ketenes, wrote his 1912 classic, Die Ketene, has there been as thorough a treatment of the field as this.
	www.loc.gov /catdir/description/wiley032/94007884.html (272 words)

	Danheiser Group - Methodology - Ketene [2 + 2] Cycloadditions
		The development of new methods for the generation of ketenes has been a long-standing concern in our laboratory.
		Our recent discovery of a new method for the synthesis of thio-substituted ketenes was highlighted on the cover of the Journal of Organic Chemistry.
		"Generation and [2 +2] Cycloadditions of Thio-Substituted Ketenes: trans-1-(4-Methoxyphenyl)-4-phenyl-3-(phenylthio)azetidin-2-one", R. Danheiser, I. Okamoto, M. Lawlor, and T. Lee, Organic Syntheses, 2003, 80, 160.
	web.mit.edu /chemistry/rld/methods/ketenes.html (242 words)

	5 (Site not responding. Last check: 2007-11-04)
		It could be proven that N,O- and N,S-Ketene acetals with a benzoyl group on the nitrogen are much more stable than the ketene acetals with a benzyl group.
		Due to the high temperatures and long reaction times needed the yields with N,O-ketene acetals are poor and side reactions are observed.
		But the overall yield of the aza-Claisen rearrangement is much higher, especially in the case of ketene acetals with crotyl or cyclohexenyl-groups.
	www.ch.ic.ac.uk /ectoc/echet98/pub/102/102-k5.html (105 words)

	Axel Mellinger: List of publications
		E. Wade, H. Clauberg, S. Kim, A. Mellinger, and C. Moore, The dynamics of rotational energy release for dissociation of singlet ketene and the singlet/triplet branching ratio, J. Phys.
		A. Mellinger, Michael V. Ashikhmin and C. Bradley Moore, "Experimental evidence for K-conservation in the dissociation of singlet ketene", J. Chem.
		M. Ashikhmin, A. Mellinger and C. Moore, The Photodissociation of Singlet Ketene by Two-Step IR+UV Excitation, Proceedings of the SPIE conference on Laser Techniques for State-Selected and State-to-State Chemistry IV, Vol.
	canopus.physik.uni-potsdam.de /~axm/research/axelpubl.html (901 words)

	Acetic acid - Wikipedia, the free encyclopedia
		See Applications below for the industrial application of this reaction.
		When heated above 440 °C, acetic acid decomposes to produce carbon dioxide and methane, or to produce ketene and water.
		Acetic acid can be detected by its characteristic smell.
	en.wikipedia.org /wiki/Acetic_acid (3067 words)

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