DOCSLIB.ORG

An Insight Into Hexamethylenetetramine: a Versatile Reagent in Organic Synthesis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Insight Into Hexamethylenetetramine: a Versatile Reagent in Organic Synthesis J IRAN CHEM SOC DOI 10.1007/s13738-013-0260-2 ORIGINAL PAPER An insight into hexamethylenetetramine: a versatile reagent in organic synthesis Navjeet Kaur • Dharma Kishore Received: 12 December 2012 / Accepted: 3 April 2013 Ó Iranian Chemical Society 2013 Abstract Hexamethylenetetramine is a versatile reagent Duff [2] and Sommelet [3] reactions hexamethylenetetra- in organic synthesis. It plays a major role in modern mine acts as the formyl carbon source, while in the Dele- organic synthesis. This review focuses on hexamine pine [4] reaction it provides the primary amino groups. reagent for its significant role in organic synthesis during Blazevic et al. [5] in 1979 listed all the experiments carried the past decades and is able to provide a valuable per- out with HMTA in the first 80 years of the last century. The spective from synthetic point of view. structure of HMTA is particularly stable, in contrast to the very reactive behavior shown by its di-hetero-substituted Keywords Hexamethylenetetramine Á Organic synthesis Á methylene groups. In addition, nitrated derivatives of Reagent HMTA were used as explosive bombs during the World War II. It is the starting material for two classic secondary explosives, RDX and HMX. Introduction Hexamethylenetetramine (HMTA) (1,3,5,7-tetraazatricy- Adamantane synthesis clo[3.3.1]decane, C6H12N4) is a fourth-cycled molecule. Hexamethylenetetramine is known by several other names, Daigle et al. [6–8] prepared a monophosphorus analog of including methenamine, urotropine, and hexamine. Hexa- hexamine, from hexamine and tris[hydroxymethyl]phos- methylenetetramine is an organic, heterocyclic chemical phine or tetrakis[hydroxymethyl]phosphonium chloride, compound, more commonly known as hexamine, is whose oxidation with hydrogen peroxide at room temper- obtained by the reaction of formaldehyde and excess of ature gave phosphoadamantane-7-oxide (Scheme 2)[5]. ammonia, either in a aqueous medium or in the vapor phase Daigle et al. [9] prepared a sulfur and phosphorus con- (Scheme 1)[1]. taining derivative of hexamine 2-thia-1,3,5-triaza-7-phos- In most areas of application, hexamine can be regarded phaadamantane-2,2-dioxide, from tris[hydroxymethy] as a special form of formaldehyde. It has the advantage that phosphine, sulphamide and hexamine in excess of form- no water is released during conversion and hydrolyzes in aldehyde (Scheme 3)[5]. acid media and slowly releases formaldehyde. It has a very low toxicity and diluted solutions can be broken down biologically. Aminoacetone semicarbazone hydrochloride synthesis Hexamine is a synthetically versatile reagent used in organic synthesis during the last years. In particular, in the Aminoacetone is a versatile starting material for many syntheses, particularly for the preparation of heterocycles. The present procedure describes a convenient method for & N. Kaur ( ) Á D. Kishore its preparation in a form which is suitable for storage. The Department of Chemistry, Banasthali University, Banasthali, Jaipur 304022, Rajasthan, India aminoacetone can be generated from aminoacetone semi- e-mail: [email protected] carbazone hydrochloride in situ. This preparation is based 123 J IRAN CHEM SOC Scheme 1 Synthesis of N hexamine H+ 6 H2C O 6 NH3 N N 6 H2O 2 NH3 N Scheme 2 Synthesis of O phosphoadamantane-7-oxide N P P H O P(CH2OH)3 2 2 H2CO N N or N N N P+(CH OH) Cl= N N 2 4 N N Scheme 3 Synthesis of O hexamine 2-thia-1,3,5-triaza-7- phosphaadamantane-2,2- P dioxide [0] N N P N N O2S H2CO N PH(CH2OH)3 H2NSO2NH2 CH3 N N - N N J H3C-I P N O2S N N N O2S - O - O Cl NNHCONH2 O Cl NH CONHNH 2Ac O H HCl 2 2 2 H C N H N 3 H3N 3 H2N CH CH pyridine, 3 H2O CH3 3 OH heat O Scheme 4 Synthesis of aminoacetone semicarbazone hydrochloride on the procedure used to synthesize 3-acetamido-2-buta- aldimine, which on hydrolysis gives the aldehyde. This none. Aminoacetone hydrochloride has been prepared from reaction is generally possible with active halides such as isopropylamine via the N,N-dichloroisopropylamine, from benzylic halides, allylic halides, a-halo ketones and pri- hexamethylenetetramine and chloroacetone (Scheme 4), by mary iodides. In this reaction, benzyl halides are refluxed reduction of nitroacetone or isonitrosoacetone, and from in DMSO along with sodium bicarbonate to give the cor- phthalimidoacetone by acid hydrolysis [10]. responding aldehydes. The reaction has recently been attempted under microwave irradiation [11]. Benzaldehyde synthesis The preparation of aromatic aldehydes from benzylic halides is an attractive route to synthesize aromatic alde- hydes (Scheme 5). One of such reaction is the Sommelet [3] reaction using hexamine as a reagent. In this process, CHO X HMTA/DMSO the first step is the reaction of hexamine with the alkyl R halide to form a quaternary salt, which on hydrolysis gives heat a primary amine, formaldehyde and ammonia. The primary R X = NO , OMe amine on reaction with the aldimine, derived from form- 2 aldehyde and ammonia, forms the corresponding aromatic Scheme 5 Synthesis of benzaldehydes 123 J IRAN CHEM SOC N N N Br r N NC6H12N3B NCl NH2 NaOH H C HCl, , 2 H2C H2C H2C heat aq. EtOH H2O Br Br Br Br Scheme 6 Synthesis of 2-bromoallylamine 2-Bromoallylamine synthesis Condensation This method gives better yields than other methods of Benzylamine and hexamine condense at 190 °C. The preparation of 2-bromoallylamine (Scheme 6), and it is the condensation product of benzylamine and hexamine poly- most convenient method for the preparation of large merizes when heated for an extended period (Scheme 8). quantities of the compound. The procedure illustrates a Depending on both temperature and time, different mix- reaction, the so-called Delepine [4] reaction, that has been tures of products are formed [5, 14]. used for the preparation of many primary aliphatic amines. The mixture of products formed from the condensation It is especially useful in the preparation of derivatives of of hexamine and benzylamine was identified and converted phenacylamine. A number of primary aliphatic amines into the open-chain isomeric products as shown in have been prepared by this method without isolation of the Scheme 9 [5, 15]. intermediate hexaminium salt [12]. In another process, the first step yielded triaza com- pound on heating the reactants for 0.5 h at 190 °C, whose further reaction at 180–200 °C produced mixture of three Cleavage of epoxides (synthesis of vicinal haloalcohols) products (Scheme 10). This mixture protects metals against corrosion under acidic conditions [5, 16, 17]. The highly regioselective cleavage of epoxides into cor- responding vicinal haloalcohols with elemental halogen has been catalyzed by hexamethylenetetramine Crown ether synthesis (Scheme 7). This method occurred under neutral and mild conditions with high yields and short reaction times in Bichromophoric compound benzophenone-{crown ether}- various aprotic solvents even when sensitive functional naphthalene (Bp-C-Np) was synthesized. 2,3,11,12-Bis(40- groups were present. The preparation of haloalcohols and formylbenzo)-18-crown-6 (BFBC) compound was pre- the complex formation of heterocyclic compounds con- pared according to the literature (Scheme 11). A mixture of taining donor nitrogen atoms, with neutral molecules such dibenzo-18-crown-6 (DBC), trifluoroacetic acid and hexa- as iodine and bromine, the HMTA compound can be methylenetetramine was stirred at 90 °C under nitrogen for reactive as a new catalyst in the addition of elemental 12 h. After the mixture was cooled, 50 ml of concentrated halogen to epoxides under mild reaction conditions with KOH and 200 ml of water were successively added. The high regioselectivity. As for the regioselectivity, attack of product was precipitated as a brown solid. The crude the nucleophile preferentially occurs at the less substituted product was collected by suction filtration and washed with epoxide carbon. This regioselectivity appears to be the acetone several times [18]. opposite of that observed in ring opening of the same epoxides with hydrohalogenic acids under classic acidic conditions [13]. Delepine reaction The Delepine reaction allows the synthesis of primary amines from alkyl halides by the reaction with hexameth- ylenetetramine and subsequent acidic hydrolysis of the resulting quaternary ammonium salt (Scheme 12). An SN2 O HO HMTA reaction leads to the hexamethylenetetramine salt. In X 2 rt, CH Cl chloroform, the starting materials are soluble whereas the 2 2 R X R products crystallize out. It is usually not possible to purify Scheme 7 Synthesis of vicinal haloalcohols the salt [2]. 123 J IRAN CHEM SOC Scheme 8 Condensation of N o hexamine and benzylamine 190 C H2 N 6 C6H5CH2NH2 6 C6H5 C N CH2 - 4 NH N 3 N H2 N C N C N CH H 3 CH2 CH2 CH2 H2C C6H5 N C6H5 C6H5 C6H5 H2 HMTA 3 C H C N CH 6 5 2 H H 190oC 2 2 NN N C N C N CH3 C6H5 C C C6H5 H2 H2 CH CH2 CH2 C6H5 C6H5 C6H5 Scheme 9 Condensation of hexamine and benzylamine Scheme 10 Condensation of H2C C6H5 hexamine and benzylamine N cooling H2 HMTA 6 C6H5 C NH2 NN C6H5 C C C6H5 H2 H2 C6H5 H2 H2 N C N CH C H C H C N CH C6H5 C N C C6H5 H 2 6 5 6 5 2 H H3C Reaction of hexamine with substituted oxiranes is a dioxane (Scheme 15) or dioxane–xylene (91 % yield) fol- modification of the Delepine reaction. On reaction with lowed by hydrolysis [20]. hexamine 1-amino-2-hydroxy alcohols are only obtained whereas reactions with primary, secondary, and tertiary amines gives rise to a mixture of 1-amino-2-hydroxy 5-Fluorovanillin synthesis alcohol and isomeric 2-amino-1-hydroxy alcohol (Scheme 13)[5].
Load more

Recommended publications
  • Thesis of a Hollow Fibre Boronic Acid Fixed Carrier Membrane System for Saccharide Separation
    University of Bath PHD Chemical modification of polysulfone Cox, Owen Award date: 2013 Awarding institution: University of Bath Link to publication Alternative formats If you require this document in an alternative format, please contact: [email protected] General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Download date: 07. Oct. 2021 Acknowledgements First and foremost I would like to thank my supervisors, Dr Semali Perera and Professor Tony James for their guidance and funding throughout my project. A big thanks to all the past and present members of the James group for generally being a friendly helpful bunch of lads. Special thanks goes to those who helped me out in my first year; Kit, Francois, Axe, Kelly, Maggy, Wenbo, Sabrina etc. for making me feel at home and welcome. An extra special thanks to Flower for constantly listening to my never ending stream of questions and not once seeming annoyed by it.
    [Show full text]
  • Review Article 51
    Review article Egypt. J. Chem. Vol. 60, No.5, pp. 723 - 751 (2017) 51 1H-Indole-3-carboxaldehyde: Synthesis and Reactions Eslam R. El-Sawy*, Heba M. Abo-Salem and Adel H. Mandour Chemistry of Natural Compounds Department, National Research Centre, P.O. Box 12622 Dokki, Giza, Egypt . 1H-Indole-3-carboxaldehyde and its derivatives have represented the key intermediates for the preparation of biologically active compounds as well indole alkaloids. Also, they are important precursors for the synthesis of divers heterocyclic derivatives because their carbonyl groups facilely undergo C–C and C–N coupling reactions and reductions. This review highlights the recent advances in 1H-indole-3-carboxaldhyde chemistry via discussing different synthetic procedures developed for the preparation of its derivatives, as well sheds the light on the most common reactions of 1H-indole-3-carboxaldhyde derivatives and exploitation of these derivatives as the blocks of many biologically active compounds. Keywords: 1H-Indole-3-carboxaldehyde, Synthesis, Reactions, Heterocycles. Introduction depressant (α-methyl-tryptamine)[4], antimicrobial (phytoalexins brassinin and cyclobrassinin) 1H-Indole-3-carboxaldhyde (I3C, 1) is a [5,6], antiviral (chondramide A) [7], anthelmintic natural compound found in tomato seedling, pea (chondriamide C) [8], monoamine oxidase inhibitor seedling, barley, lupine, cabbage and cotton [1]. (aplysinopin) [9], anti-plasmodial (isocryptolepine) 1H-Indole-3-carboxaldehyde (1) represents an [10], antifungal (phytoalexine caulilexins A-C) important starting and intermediate compound [11], inhibit DNA replication and transcription for building many various synthetic and natural (cryptosanginolentine 1) [12] and muscle relaxant biologically active compounds especially with (α,β-cyclopiazonic acid)[13] activities (Fig. 1).
    [Show full text]
  • [Cu2(Mand)2(Hmt)]–MOF: a Synergetic Effect Between Cu(II)
    Article 3 1 [Cu2(mand)2(hmt)]–MOF: A Synergetic Effect between Cu(II) and Hexamethylenetetramine in the Henry Reaction 1 1 1 2 2, Horat, iu Szalad , Natalia Candu , Bogdan Cojocaru , Traian D. Păsătoiu , Marius Andruh * and Vasile I. Pârvulescu 1,* 1 Department of Organic Chemistry, Biochemistry and Catalysis, Catalysis and Catalytic Processes Research Centre, Faculty of Chemistry, University of Bucharest, Bd. Regina Elisabeta nr. 4-12, 020462 Bucharest, Romania; [email protected] (H.S.); [email protected] (N.C.); [email protected] (B.C.) 2 Faculty of Chemistry, University of Bucharest, Department of Inorganic Chemistry, 23 Dumbrava Ro¸sie Street, sector 2, 020462 Bucharest, Romania; [email protected] * Correspondence: [email protected] (M.A.); [email protected] (V.I.P.) Received: 9 January 2020; Accepted: 12 February 2020; Published: 13 February 2020 3 Abstract: [Cu2(mand)2(hmt)] H2O (where mand is totally deprotonated mandelic acid (racemic 1 · mixture) and hmt is hexamethylenetetramine) proved to be a stable metal–organic framework (MOF) structure under thermal activation and catalytic conditions, as confirmed by both the in situ PXRD (Powder X-ray diffraction) and ATR–FTIR (Attenuated total reflection-Fourier-transform infrared spectroscopy) haracterization. The non-activated MOF was completely inert as catalyst for the Henry reaction, as the accessibility of the substrates to the channels was completely blocked by H-bonded water to the mand entities and CO2 adsorbed on the Lewis basic sites of the hmt. Heating at 140 ◦C removed these molecules. Only an insignificant change in the relative ratios of the XRD facets due to the capillary forces associated to the removal of the guest molecules from the network has been observed.
    [Show full text]
  • 0996 Date: February 2009 Revision: June 2016 DOT Number: UN 1328
    Right to Know Hazardous Substance Fact Sheet Common Name: HEXAMINE Synonyms: Hexamethylenetetramine; Methenamine CAS Number: 100-97-0 Chemical Name: 1,3,5,7-Tetraazatricyclo[3.3.1.13,7]Decane RTK Substance Number: 0996 Date: February 2009 Revision: June 2016 DOT Number: UN 1328 Description and Use EMERGENCY RESPONDERS >>>> SEE LAST PAGE Hexamine is a colorless to white, odorless, crystalline (sand- Hazard Summary like) powder. It is used in adhesives, coatings, and sealing Hazard Rating NJDHSS NFPA compounds, and as a medication. HEALTH 2 - FLAMMABILITY 1 - REACTIVITY 0 - COMBUSTIBLE POISONOUS GASES ARE PRODUCED IN FIRE Reasons for Citation Hazard Rating Key: 0=minimal; 1=slight; 2=moderate; 3=serious; Hexamine is on the Right to Know Hazardous Substance 4=severe List because it is cited by DOT. Hexamine can affect you when inhaled. Contact can irritate the skin and eyes. Inhaling Hexamine can irritate the nose, throat and lungs. Hexamine can cause nausea, vomiting, diarrhea and abdominal pain. Hexamine may cause a skin allergy and an asthma-like allergy. SEE GLOSSARY ON PAGE 5. Finely dispersed Hexamine particulate or powdered dust is an explosion hazard. FIRST AID Eye Contact Immediately flush with large amounts of water for at least 15 minutes, lifting upper and lower lids. Remove contact Workplace Exposure Limits lenses, if worn, while rinsing. No occupational exposure limits have been established for Skin Contact Hexamine. However, it may pose a health risk. Always follow Quickly remove contaminated clothing. Immediately wash safe work practices. contaminated skin with large amounts of water. Inhalation Remove the person from exposure. Begin rescue breathing (using universal precautions) if breathing has stopped and CPR if heart action has stopped.
    [Show full text]
  • (12) United States Patent (10) Patent No.: US 8,269,044 B2 Takano Et Al
    USOO826904.4B2 (12) United States Patent (10) Patent No.: US 8,269,044 B2 Takano et al. (45) Date of Patent: *Sep. 18, 2012 (54) METHOD FOR SELECTIVELY PRODUCING OTHER PUBLICATIONS PRIMARY AMINE COMPOUND M. S. Gibson, et al. The Gabriel Synthesis of Primary Amines, Angew. Chem. Internat. Edit., vol.7. (1968), pp. 919-930. (75) Inventors: Naoyuki Takano, Ibaraki (JP); HanYinglin, et al., A Convenient Synthesis of Primary Amines Using Kazuyuki Tanaka, Oita (JP); Shinzo Sodium Diformylamide as a Modified Gabriel Reagent, Synthesis, Seko, Toyonaka (JP) 1990, pp. 122-124. Nikola Blazevic, et al., Hexamethylenetetramine, A Versatile (73) Assignee: Sumitomo Chemical Company, Reagent in Organic Synthesis, Synthesis, 1979, pp. 161-176. Limited, Tokyo (JP) Chrisey et al., “Tris-N,N',N" (3', 4', 5'-Trimethoxyphenethyl)-1, 3, 5-Hexahydrotriazine, a Methylenemescaline Trimer: Characteriza (*) Notice: Subject to any disclaimer, the term of this tion and Selective Cyclization to Anhalinine Under Non-Aqueous patent is extended or adjusted under 35 Conditions.” Heterocycles, vol. 29, No. 6, 1989, pp. 1179-1183. Chinese Office Action issued in the corresponding Chinese Patent U.S.C. 154(b) by 1046 days. Application No. 200680052617.1 on Aug. 18, 2011 (with English This patent is Subject to a terminal dis translation). claimer. Japanese Office Action for Application No. 2006-336654 datedMar. 13, 2012 (with English translation). (21) Appl. No.: 12/097,234 * cited by examiner Primary Examiner — Venkataraman Balasubramanian (22) PCT Filed: Dec. 14, 2006 (74) Attorney, Agent, or Firm — Birch, Stewart, Kolasch & Birch, LLP (86). PCT No.: PCT/UP2OO6/324938 (57) ABSTRACT S371 (c)(1), Disclosed is a method for producing a primary amine com (2), (4) Date: Jun.
    [Show full text]
  • United States Patent Office Patented Oct
    3,004,026 United States Patent Office Patented Oct. 10, 1961 1. 3,004,026 septic. Thus, it has been recommended that a salt ex-. HEXAMETHYLENETETRAMINE HIPPURATE hibiting an acid reaction, such as ammonium chloride, Alexander Galat, 126 Buckingham Road, Yonkers, NY. ammonium nitrate, sodium acid phosphate or the like, No Drawing. Filed Aug. 28, 1959, Ser. No. 836,618 be administered together with Methenamine. However, 1. Claim. C. 260-248.5) 5 impractically and/or dangerously high dosages of such salts must be given in order to make the urine acidic and This invention relates to a new and useful organic com even so acidification of the urine does not occur with all pound. More particularly, this invention relates to a new patients. - . organic compound useful as a urinary tract antiseptic. In Another approach that has been employed in an at an even more specific aspect thereof, this invention relates O tempt to solve the difficulty involves administering to hexamethylenetetramine hippurate. Methenamine in the form of a salt with an organic acid. The principal object of this invention is to provide It is postulated that decomposition of such a salt in the hexamethylenetetramine hippurate, a new organic com urine will result in the production of the acid medium re pound of high utility. quired for manifestation of the antiseptic action of Corollary objects of this invention will become appar 15 Methenamine. ent as the description thereof proceeds. Salts of Methenamine with such acids as anhydro For the better understanding of this invention, the methylenecitric, acetylsalicylic, borocitric, citrosulfuric, following example is a complete description of a pre mandelic, phenoxyacetic, salicyclic, sulfosalicylic, salicyl ferred procedure for the preparation of the new and use oxyacetic, sulfoxylic, and the like have been prepared ful compound of this invention.
    [Show full text]
  • Vilsmeier-Haack Reactions in Synthesis of Heterocycles: an Overview
    Chapter 2 Vilsmeier-Haack reactions in Synthesis of Heterocycles: An Overview 2.1 Introduction In 1927 Vilsmeier and Haack observed that N-methylformanilide 1 can formylate aniline derivatives in the presence of POCl3. Later the reaction was extended using simple formamide derivatives like N,N- dimethylformamide, N-formylpiperidine, N-formylmorpholine etc. to formylate electron rich aromatic and aliphatic substrates, and these types of reactions are known as Vilsmeier-Haack reactions.2 A Vilsmeier- Haack reagent 3 is produced when a disubstituted formamide or amide, typically N,N-dimethylformamide (DMF) 1 is treated with an acid halide, frequently phosphorous oxychloride, though to a lesser extent, oxalyl chloride (Scheme 2.1). O OPOCl 2 Cl POCl H N 3 H N H N Cl OPOCl 2 1 2 3 Scheme 2.1 A large number of aromatic and aliphatic substrates, particularly the carbonyl compounds containing methyl or methylene groups adjacent to the carbonyl groups undergo iminoalkylation by the Vilsmeier-Haack reagent.2 Hydrolysis of iminium salts formed in this reaction afford aldehyde derivatives. Usually the reactions of active methylene compounds with reagents of the Vilsmeier type afford -chloromethyleneiminium salts or -chlorovinylaldehydes, which have been recognized as useful intermediates 13 in heterocyclic synthesis. An overview of important Vilsmeier-Haack formylation reactions and Vilsmeier-Haack reactions leading to heterocycles is included in this chapter. 2.2 The Vilsmeier-Haack reactions of aromatic compounds The Vilsmeier-Haack reactions of electron rich aromatic compounds, generally, afford aldehyde derivatives in good yields. For example, N,N- dimethylaniline 4 afford p-N,N-dimethylaminobenzaldehyde 6 (Scheme 2.2).2a Anthracenes, naphthalenes and other polycyclic aromatic compounds also undergo facile formylation.
    [Show full text]
  • Formylation of Electron-Rich Aromatic Rings Mediated by Dichloromethyl Methyl Ether and Ticl4: Scope and Limitations
    Molecules 2015, 20, 5409-5422; doi:10.3390/molecules20045409 OPEN ACCESS molecules ISSN 1420-3049 www.mdpi.com/journal/molecules Article Formylation of Electron-Rich Aromatic Rings Mediated by Dichloromethyl Methyl Ether and TiCl4: Scope and Limitations Iván Ramos-Tomillero 1,2, Marta Paradís-Bas 1,2, Ibério de Pinho Ribeiro Moreira 3,4, Josep María Bofill 2,4, Ernesto Nicolás 2,5,* and Fernando Albericio 1,2,6,7,8,* 1 Institute for Research in Biomedicine (IRB Barcelona), Barcelona 08028, Spain; E-Mails: [email protected] (I.R.-T.); [email protected] (M.P.-B.) 2 Deparment of Organic Chemistry, University of Barcelona, Barcelona 08028, Spain; E-Mail: [email protected] 3 Department of Physical Chemistry, University of Barcelona, Barcelona 08028, Spain; E-Mail: [email protected] 4 Institut de Química Teòrica i Computacional (IQTCUB), University of Barcelona, Barcelona 08028, Spain 5 Institut de Biomedicina (IBUB), University of Barcelona, Barcelona 08028, Spain 6 CIBER-BBN, Barcelona 08028, Spain 7 School of Chemistry, University of KwaZulu-Natal, Durban 4000, South Africa 8 School of Chemistry, Yachay Tech, Yachay City of Knowledge, Urcuqui 100119, Ecuador * Authors to whom correspondence should be addressed; E-Mails: [email protected] (E.N.); [email protected] or [email protected] (F.A.); Tel.: +34-93-403-7088 (F.A.). Academic Editor: Jean Jacques Vanden Eynde Received: 27 January 2015 / Accepted: 12 March 2015 / Published: 26 March 2015 Abstract: Here the aromatic formylation mediated by TiCl4 and dichloromethyl methyl ether previously described by our group has been explored for a wide range of aromatic rings, including phenols, methoxy- and methylbenzenes, as an excellent way to produce aromatic aldehydes.
    [Show full text]
  • F1y3x CHAPTER 29 ORGANIC CHEMICALS VI 29-1 Notes 1
    )&f1y3X CHAPTER 29 ORGANIC CHEMICALS VI 29-1 Notes 1. Except where the context otherwise requires, the headings of this chapter apply only to: (a) Separate chemically defined organic compounds, whether or not containing impurities; (b) Mixtures of two or more isomers of the same organic compound (whether or not containing impurities), except mixtures of acyclic hydrocarbon isomers (other than stereoisomers), whether or not saturated (chapter 27); (c) The products of headings 2936 to 2939 or the sugar ethers and sugar esters, and their salts, of heading 2940, or the products of heading 2941, whether or not chemically defined; (d) Products mentioned in (a), (b) or (c) above dissolved in water; (e) Products mentioned in (a), (b) or (c) above dissolved in other solvents provided that the solution constitutes a normal and necessary method of putting up these products adopted solely for reasons of safety or for transport and that the solvent does not render the product particularly suitable for specific use rather than for general use; (f) The products mentioned in (a), (b), (c), (d) or (e) above with an added stabilizer necessary for their preservation or transport; (g) The products mentioned in (a), (b), (c), (d), (e) or (f) above with an added antidusting agent or a coloring or odoriferous substance added to facilitate their identification or for safety reasons, provided that the additions do not render the product particularly suitable for specific use rather than for general use; (h) The following products, diluted to standard strengths, for the production of azo dyes: diazonium salts, couplers used for these salts and diazotizable amines and their salts.
    [Show full text]
  • Modification of Chitosan for Simultaneous Antioxidant
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ScholarBank@NUS MODIFICATION OF CHITOSAN FOR SIMULTANEOUS ANTIOXIDANT AND ANTIBACTERIAL FUNCTIONS CHEN FEI NATIONAL UNIVERSITY OF SINGAPORE 2009 MODIFICATION OF CHITOSAN FOR SIMULTANEOUS ANTIOXIDANT AND ANTIBACTERIAL FUNCTIONS CHEN FEI (B. ENG ECUST) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING DEPARTMENT OF CHEMICAL AND BIOMOLECULAR ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2009 ACKNOWLEDGEMENT Studying for a degree is a huge process that evolves over time and involves many role players, some of whom do not even realize the part they have played. I owe a huge debt to my supervisor Prof. Neoh Koon Gee, who gave me confidence and guidance to persist in my research works. I also want to express my thanks to my colleagues, Dr. Shi Zhilong, Chua Poh Hui, Tan Lihan, Zhang Fan and Lim Siew Lay. Discussing and talking with them have always inspired me on my research work. Finally, I would like to appreciate the financial support from the National University of Singapore. i TABLE OF CONTENTS ACKNOWLEDGEMENT i TABLE OF CONTENTS ii SUMMARY vi NOMENCLATURE viii LIST OF FIGURES ix LIST OF SCHEMES x LIST OF TABLES xi 1 Introduction 1 2 Literature review 5 2.1 Chitosan 5 2.1.1 Sources of chitosan 5 2.1.2 Chemistry of chitosan 7 2.1.3 Biological properties of chitosan 9 2.1.4 Applications of chitosan 11 2.2 Ascorbic acid 14 2.3 Essential oils 15 2.3.1 Major components of essential oils 15 2.3.2 Antibacterial activity of essential oils 16 2.3.3
    [Show full text]
  • Zinc Oxide—From Synthesis to Application: a Review
    Materials 2014, 7, 2833-2881; doi:10.3390/ma7042833 OPEN ACCESS materials ISSN 1996-1944 www.mdpi.com/journal/materials Review Zinc Oxide—From Synthesis to Application: A Review Agnieszka Kołodziejczak-Radzimska * and Teofil Jesionowski Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, M. Sklodowskiej-Curie 2, PL-60965 Poznan, Poland; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +48-61-665-3626; Fax: +48-61-665-3649. Received: 17 December 2013; in revised form; 25 March 2014 / Accepted: 27 March 2014 / Published: 9 April 2014 Abstract: Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The first part of this paper presents the most important methods of preparation of ZnO divided into metallurgical and chemical methods. The mechanochemical process, controlled precipitation, sol-gel method, solvothermal and hydrothermal method, method using emulsion and microemulsion enviroment and other methods of obtaining zinc oxide were classified as chemical methods. In the next part of this review, the modification methods of ZnO were characterized. The modification with organic (carboxylic acid, silanes) and inroganic (metal oxides) compounds, and polymer matrices were mainly described. Finally, we present possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced. This review provides useful information for specialist dealings with zinc oxide. Keywords: zinc oxide; synthesis; modification; application 1. Introduction Zinc oxide, with its unique physical and chemical properties, such as high chemical stability, high electrochemical coupling coefficient, broad range of radiation absorption and high photostability, is a multifunctional material [1,2].
    [Show full text]
  • Vilsmeier-Haack Reagent
    Current Chemistry Letters 2 (2013) 187–196 Contents lists available at Growing Science Current Chemistry Letters homepage: www.GrowingScience.com/ccl Vilsmeier-Haack reagent: A facile synthesis of 2-(4-chloro-3,3-dimethyl-7- phenoxyindolin-2-ylidene)malonaldehyde and transformation into different heterocyclic compounds Laya Roohia, Arash Afghanb* and Mehdi M. Baradarania aDepartment of Chemistry, Faculty of Science, University of Urmia, Urmia 57153-165, Iran bDepartment of Chemical Engineering, Urmia University of Technology, Urmia 57155-419, Iran C H R O N I C L E A B S T R A C T Article history: 2-(5-Chloro-2-phenoxyphenyl)hydrazine was converted to corresponding 3H-indole by Fischer Received March 20, 2013 method utilizing the isopropyl methyl ketone in acetic acid. The reaction of 3H-indole with Received in Revised form Vilsmeier-Haack reagent furnished aminomethylene malonaldehyde in excellent yield while the July 7, 2013 reactions of malonaldehyde with hydrazine, arylhydrazines, amines, cyanoacetamide and Accepted 28 July 2013 hydroxylamine hydrochloride, led to the corresponding pyrazole derivatives, enamines, Available online cyanopyridone, and cyanoacetamide derivatives respectively. 30 July 2013 Keywords: Vilsmeier-Haack reagent Fischer indole synthesis malonaldehydes pyrazoles enamines cyanoacetamide cyanopyridone © 2013 Growing Science Ltd. All rights reserved. 1. Introduction Chloromethyleneiminium salts, commonly known as highly versatile Vilsmeier-Haack reagent,1 usually generated in situ by the treatment of POCl3 with an N,N-disubstituted formamides (e.g., DMF), is very useful in the synthetic transformations. Selected applications of this reagent include: formylation,2,3 cyclohaloaddition,4 cyclization5 and ring annulations.6 A wide variety of alkene derivatives,7 carbonyl compounds,8 activated methyl and methylene groups bearing chemicals,9 and oxygen10 as well as nitrogen nucleophiles11 undergo the reactions with Vilsmeier reagent to yield the corresponding iminium salts.
    [Show full text]