DOCSLIB.ORG

Basicity-Aromatic Amines

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Organic Lecture Series AminesAmines Epinephrine (adrenaline) Chapter 23 1 Organic Lecture Series Structure & Classification • Amines are classified as – 1°, 2°, or , 3° amines: amines in which 1, 2, or 3 hydrogens of NH3 are replaced by alkyl or aryl groups 2 o o 2 Structure & ClassificationOrganic Lecture Series • Amines are further divided into aliphatic, aromatic, and heterocyclic amines: – aliphatic amine: an amine in which nitrogen is bonded only to alkyl groups – aromatic amine: an amine in which nitrogen is bonded to one or more aryl groups CH CH : 3 3 NH 2 N-H: CH2 -N-CH: 3 Aniline N-Methylaniline Benzyldimethylamine (a 1° aromatic amine) (a 2° aromatic amine) (a 3° aliphatic amine) 3 Organic Lecture Series Structure & Classification – heterocyclic amine: an amine in which nitrogen is one of the atoms of a ring N N N N H H H PyrrolidinePiperidine Pyrrole Pyridine (heterocyclic aliphatic amines) (heterocyclic aromatic amines) 4 Organic Lecture Series Structure & Classification CH3 N H H COOCH3 (a) (b) N (c) N CH OCH H N 3 6 5 (S)-Coniine (S)-Nicotine Co cain e O Coniine is a poisonous alkaloid found in poison hemlock and the Yellow Pitcher Plant, and contributes to hemlock's fetid smell. It is a neurotoxin which disrupts the peripheral nervous system. Caffeine 5 Organic Lecture Series Nomenclature • Aliphatic amines: replace the suffix -eofe the parent alkane by -amine NH2 NH2 H2 N NH2 2-Propanamine (S)-1-Phenyl- 1,6-Hexanediamine ethanamine 6 Organic Lecture Series Nomenclature • The IUPAC system retains the name aniline: NH2 NH2 NH2 NH2 OCH3 NO2 CH3 Aniline 4-Nitroaniline 4-Methylaniline 3-Methoxyaniline (p-Nitroaniline) (p-Toluidine) (m-Anisidine) 7 Organic Lecture Series Nomenclature • Among the various functional groups discussed in the text, -NH2 is one of the lowest in order of precedence OH OH H2 N H2 N COOH NH2 2-Aminoethanol (S)-2-Amino-3-methyl- 4-Aminobenzoic acid 1-butanol 8 Organic Lecture Series Nomenclature • Common names for most aliphatic amines are derived by listing the alkyl groups bonded to nitrogen in one word ending with the suffix -amine H CH NH 3 2 NH2 N Et 3 N Methylamine tert-Butylamine Dicyclopentylamine Triethylamine 9 Organic Lecture Series Nomenclature • When four groups are bonded to nitrogen, the compound is named as a salt of the corresponding amine - Cl + - + Me 4 N Cl NCH2 (CH2 )12CH3 - Ph CH2 NMe3 OH Tetramethy Tetradecylpyridinium chloride Benzyltrimethyl- ammonium (Cetylp yridin ium chloride) ammonium chloride hydroxide 10 Organic Lecture Series Physical Properties • Amines are polar compounds, and both 1° and 2° amines form intermolecular hydrogen bonds – N-H- - -N hydrogen bonds are weaker than O- H- - -O hydrogen bonds because the difference in electronegativity between N and H (3.0 - 2.1 =0.9) is less than that between O and H (3.5 - 2.1 = 1.4) CH 3 CH 3 CH 3 NH 2 CH 3 OH MW (g/mol) 30.1 31.1 32.0 bp (°C)-88.6 -6.3 65.0 11 Organic Lecture Series Basicity • All amines are weak bases, and aqueous solutions of amines are basic H H + - CH 3 -N + H- O- H CH 3 -N-H O-H H H Methylamine Methylammonium hydroxide 12 Organic Lecture Series Basicity – it is common to discuss their basicity by reference to the acid ionization constant of the conjugate acid: + + CH 3 NH3 + H2 O CH3 NH2 + H3 O + [CH NH ][H O ] 3 2 3 -1 1 Ka = + = 2.29 x 10 pKa = 10.64 [CH3 NH3 ] 13 Organic Lecture Series Basicity – using values of pKa, comparisons of the acidities of amine conjugate acids with other acids can be made: + - CH 3 NH2 + CH3 COOH CH3 NH3 + CH 3 COO pKeq = -5.88 5 pKa 4.76 pKa 10.64 Keq = 7.6 x 10 (stronger (weaker acid) acid) : + + R—NH2 + H RNH3 conjugate acid 14 Basicity-Aliphatic Amines Organic Lecture Series Amine Structure pKa pKb Ammonia NH3 9.26 4.74 Primary Amines methylamine CH3 NH2 10.64 3.36 ethylamine CH3 CH2 NH2 10.81 3.19 cyclohexy lam ine C6 H11NH2 10.66 3.34 Secondary A min es dimethylamine (CH3 ) 2 NH 10.73 3.27 diethylamine (CH3 CH2 )2 NH 10.98 3.02 Tertiary Amines trimethylamine (CH3 ) 3 N 9.81 4.19 triethylamine (CH3 CH2 )3 N 10.75 3.25 : + + R—NH2 + H RNH3 conjugate acid 15 Organic Lecture Series Basicity-Aromatic Amines Amine Structure pKa of Conjugate Acid Aromatic Amines Aniline NH2 4.63 4-Methylaniline Note the effect of CH NH 5.08 3 2 Ar-X on the acidity: 4-Chloroaniline Cl NH2 4.15 The stronger the - 4-Nitroaniline O2 N NH2 1.0 e withdrawing effect, the weaker Heterocyclic Aromatic Amines the base & Pyrid ine N 5.25 stronger the conj N acid. Im idazo le 6.95 N H 16 Organic Lecture Series Basicity-Aromatic Amines – aromatic amines are considerably weaker bases than aliphatic amines + - NH2 + H2 O NH3 OH pKa = 10.66 Cyclohexylamine Cyclohexylammonium hydroxide + - NH2 + H2 O NH3 OH pKa = 4.63 Aniline Anilinium hydroxide 17 Organic Lecture Series Basicity-Aromatic Amines • Aromatic amines are weaker bases than aliphatic amines because of two factors – resonance stabilization of the free base, which is lost on protonation H HH+ H + H H + H NNNHN . H . H unhybridized 2p orbital of N . .. H H . N H nitrogen is sp2 hybridized H H 18 Organic Lecture Series Basicity-Aromatic Amines – the greater electron-withdrawing inductive effect of the sp2-hybridized carbon of an aromatic amine compared with the sp3- hybridized carbon of an aliphatic amine also decreases basicity • Electron-releasing, such as alkyl groups, increase the basicity of aromatic amines • Electron-withdrawing groups, such as halogens, the nitro group, and a carbonyl group decrease the basicity of aromatic amines by a combination of resonance and inductive effects 19 Organic Lecture Series Basicity-Aromatic Amines 4-nitroaniline is a weaker base than 3-nitroaniline O2 N NH2 O2 N NH2 3-Nitroaniline 4-Nitroaniline pKa 2.47 pKa 1.0 delocalization of the nitrogen lone pair onto the oxygen atoms of the nitro group - O O + + NNH2 + N NH2 O - - O 20 Organic Lecture Series Basicity-Aromatic Amines • Heterocyclic aromatic amines are weaker bases than heterocyclic aliphatic amines N N N N H H PiperidinePyridine Imidazole pK 6.95 pKa 10.75 pKa 5.25 a 21 Basicity-Aromatic Amines Organic Lecture Series – in pyridine, the unshared pair of electrons on N is not part of the aromatic sextet . an sp2 hybrid orbital; the electron H H . pair in this orbital is not a part of the aromatic sextet H . N : 2 H H nitrogen is sp hybridized – pyridine is a weaker base than heterocyclic aliphatic amines because the free electron pair on N lies in an sp2 hybrid orbital (33% s character) and is held more tightly to the nucleus than the free electron pair on N in an sp3 hybrid orbital (25% s character) 22 Organic Lecture Series Reaction with Acids • All amines, whether soluble or insoluble in water, react quantitatively with strong acids to form water-soluble salts OH OH HO NH HO NH + Cl- 2 H O 3 + HCl 2 HO HO (R)-Norepinephrine (R)-Norepinephrine hydrochloride (only slightly soluble in water) (a water-soluble salt) 23 Organic Lecture Series Preparation • A summary of synthetic methods: – nucleophilic ring opening of epoxides by ammonia and amines (11.9B) – addition of nitrogen nucleophiles to aldehydes and ketones to form imines (Section 16.8) – reduction of imines to amines (16.8A) – reduction of amides by LiAlH4 (18.10B) – reduction of nitriles to a 1° amine (18.10C) – nitration of arenes followed by reduction of the NO2 group to 1° amines (22.1B) 24 Preparation Organic Lecture Series • Alkylation of ammonia and amines by SN2 SN2 + - CH3 Br + NH3 CH3 NH3 Br Methylammonium bromide – unfortunately, such alkylations give mixtures of products through a series of proton transfer and nucleophilic substitution reactions CH3 Br+ NH3 + - + - + - + - CH 3 NH3 Br +++(CH3 ) 2 NH2 Br (CH3 ) 3 NH Br (CH3 ) 4 N Br These arise from N-polyalkylation 25 Organic Lecture Series Preparation via Azides - • Alkylation of azide ion, N3 : : - - : ++: - - N 3 ::NNNN: RN 3 R NN Azide ion An alkyl azide (a good nucleophile) + - K N3 1. LiAlH4 Ph CH 2 Cl Ph CH2 N3 Ph CH2 NH2 2. H O Benzyl ch loride Ben zyl azid e2 Benzylamin e 26 Organic Lecture Series Preparation via Azides – alkylation of azide ion + ArCO H 1. K N - 3 O 3 2. H2 O Cy clo hexen e 1,2-Epoxy- cyclohexane (chiral) OH OH 1. LiAlH4 2. H2 O N3 NH2 trans-2-Azido- trans-2-Amino- cyclohexan ol cyclohexanol (racemic) (racemic) 27 Organic Lecture Series Reaction with HNO2 • Nitrous acid, a weak acid, is most commonly prepared by treating NaNO2 with aqueous H2SO4 or HCl HNO + H OHO+ - 2 2 3 + NO2 pKa = 3.37 • In its reactions with amines, nitrous acid – participates in proton-transfer reactions – is a source of the nitrosyl cation, NO+, a weak electrophile 28 Organic Lecture Series Reaction with HNO2 • NO+ is formed in the following way: (1) + (2) H OON + H+ HNOO H + + H O + NO NO H The nitrosyl cation – Focus upon reactions of HNO2 with 1° aliphatic and aromatic amines 29 Organic Lecture Series RNH2 with HNO2 • 1° aliphatic amines give a mixture of unrearranged and rearranged substitution and elimination products, all of which are produced by way of a diazonium ion and its loss of N2 to give a carbocation. + + • Diazonium ion: an RN2 or ArN2 ion 30 Organic Lecture Series 1° RNH2 with HNO2 • Formation of a diazonium ion Step 1: reaction of a 1° amine with the nitrosyl cation keto-enol H : : : : + : : : tautomerism : : : : : R-NH2 + NR-N-N=OO R-N=N-O-H A 1° aliphatic An N-nitrosamine A diazotic acid amine Step 2: protonation followed by loss of water H + : : : H •• •• + -H2 O R-N=N-O-H: R-N N O- H •• A diazotic acid + • • + • • • R NN R + NN A diazonium ion A carbo- cation 31 NOT responsible for mechanism Organic Lecture Series 1° RNH2 with HNO2 • Aliphatic diazonium ions are unstable and lose N2 to give a carbocation which may 1.
Recommended publications
  • P-Chloro-O-Toluidine and Its Hydrochloride Al

    P-Chloro-O-Toluidine and Its Hydrochloride Al

    Report on Carcinogens, Fourteenth Edition For Table of Contents, see home page: http://ntp.niehs.nih.gov/go/roc p-Chloro-o-toluidine and Its Hydrochloride al. 1979, Bentley et al. 1986, IARC 2000). In organs from animals ex- posed to p-chloro-o-toluidine, DNA breakage was detected by single- CAS Nos. 95-69-2 and 3165-93-3 cell gel electrophoresis (comet assay) in mouse liver, urinary bladder, lung, and brain and in rat liver and kidney (Sekihashi et al. 2002). Reasonably anticipated to be human carcinogens First listed in the Eighth Report on Carcinogens (1998) Properties Also known as 4-chloro-o-toluidine or 4-chloro-2-methylaniline p-Chloro-o-toluidine is a chlorinated aromatic amine that exists as a grayish-white crystalline solid or leaflet, andp -chloro-o-toluidine hy- CH3 drochloride is a buff-colored or light-pink powder at room tempera- ture. The base compound is practically insoluble in water or carbon NH2 tetrachloride but is soluble in ethanol or dilute acid solutions. It is stable under normal temperatures and pressures (Akron 2009). Phys- Cl ical and chemical properties of p-chloro-o-toluidine are listed in the following table. No physical and chemical properties for the hydro- Carcinogenicity chloride were found except its molecular weight of 178.1 and melt- p-Chloro-o-toluidine and its hydrochloride salt are reasonably antic‑ ing range of 265°C to 270°C (IARC 2000, Weisburger 1978). ipated to be human carcinogens based on limited evidence of carci- Property Information nogenicity from studies in humans and evidence of carcinogenicity Molecular weight 141.6a from studies in experimental animals.
  • Mdi), 1,6 Hexamethylene Diisocyanate (Hdi

    Mdi), 1,6 Hexamethylene Diisocyanate (Hdi

    4.03.11. PRODUCTION OF ISOCYANATES FOR POLYURETHANE PRO- DUCTION CHEMICALS AND ALLIED APPLICATION NOTE 4.03.11 PRODUCTION OF ISOCYANATES FOR POLYURETHANE PRODUCTION METHYLENE DIPHENYL DIISOCYANATE (MDI), 1,6 HEXAMETHYLENE DIISOCYANATE (HDI) Typical end products Polyurethane foam for different applications, for example, bedding, of materials can be produced to meet the needs for furniture, packaging, coatings and elastomers. specific applications. Chemical curve: R.I. for MDI at Ref. Temp. of 25˚C Application The most commonly used isocyanates for the production of PU are methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI). If color and transparency are important, an aliphatic diisocyanate such as hexamethylene diisocyanate (HDI) is used. The first step in the production of polyurethane is the synthesis of the raw materials. The diisocyanate is typically produced from basic raw materials via nitration, hydrogenation and phosgenation. The feedstock and initial processing steps depend on the Introduction desired isocyanate, but all go through a phosgenation step. Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications. For instance, for the production of MDI, benzene and They are used in the manufacture of many different nitric acid are reacted to produce nitrobenzene. After items, such as paints, liquid coatings, elastomers, a hydrogeneration step, the nitrobenzene is converted insulators, elastics, foams and integral skins. to aniline. It is then condensed with formaldehyde to produce methylene diphenyl diamine (MDA), the Polyurethanes are produced by polymerization of precursor for MDI. The MDA is fed to a phosgenation a diisocyanate with a polyol. Because a variety of reactor where it reacts with phosgene to produce the diisocyanates and a wide range of polyols can be end-product MDI.
  • PDMS-Based Antimicrobial Surfaces for Healthcare Applications

    PDMS-Based Antimicrobial Surfaces for Healthcare Applications

    PDMS-based Antimicrobial Surfaces for Healthcare Applications This thesis is presented to UCL in partial fulfilment of the requirements for the Degree of Doctor of Philosophy Ekrem Ozkan Supervised by Professor Ivan P. Parkin Materials Chemistry Research Centre Dr Elaine Allan Division of Microbial Diseases 2017 1 DECLARATION I, Ekrem Ozkan confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 2 ABSTRACT This thesis describes two types of approaches for reducing the incidence of hospital- acquired infections (HAIs), which are chemical approaches that inactivate bacteria that adhere to the surface i.e. bactericidal activity and physical approaches that inhibit initial bacterial attachment to the surface i.e. anti-biofouling activity. Specifically, the antimicrobial polydimethylsiloxane (PDMS)-based systems detailed in this thesis are: (i) photosensitizer, crystal violet (CV),-coated PDMS for both medical device and hospital touch surface applications, (ii) crystal violet-coated, zinc oxide nanoparticle-encapsulated PDMS for hospital touch surface applications, (iii) superhydrophobic antibacterial copper coated PDMS films via aerosol assisted chemical vapour deposition (AACVD) for hospital touch surface applications and (iv) slippery copper-coated PDMS films to prevent biofilm formation on medical devices. The materials were characterized using techniques including: X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis absorbance spectroscopy, water-contact angle measurement and microbiology tests. Functional testing indicated that CV-coated samples were suitable for targeted applications and showed potent light-activated antimicrobial activity when tested against model Gram-positive bacteria, Staphylococcus aureus, and Gram-negative bacteria, Escherichia coli, associated with hospital-acquired infections, with > 4 log reduction in viable bacterial numbers observed.
  • Ortho-TOLUIDINE

    Ortho-TOLUIDINE

    ortho-TOLUIDINE 1. Exposure Data 1.1 Chemical and physical data 1.1.1 Nomenclature Chem. Abstr. Serv. Reg. No.: 95–53–4 CAS Name: 2-Methylbenzenamine Synonyms: 1-Amino-2-methylbenzene; 2-amino-1-methylbenzene; 2-aminotoluene; ortho-aminotoluene; 2-methyl-1-aminobenzene; 2-methylaniline; ortho-methylaniline; ortho-methylbenzenamine; 2-methylphenylamine; 2- tolylamine; ortho-tolylamine 1.1.2 Structural formula, molecular formula, and relative molecular mass NH2 CH3 C7H9N Rel. mol. mass: 107.15 1.1.3 Chemical and physical properties of the pure substance Description: Light yellow liquid becoming reddish brown on exposure to air and light (O’Neil, 2006) Boiling-point: 200–201 °C (O’Neil, 2006) Melting-point: −14.41 °C (Lide, 2008) Solubility: Slightly soluble in water; soluble in diethyl ether, ethanol and dilute acids (O’Neil, 2006) Octanol/water partition coefficient: log P, 1.29–1.32 (Verschueren, 2001) –407– 408 IARC MONOGRAPHS VOLUME 99 1.1.4 Technical products and impurities No information was available to the Working Group. 1.1.5 Analysis ortho-Toluidine is the most widely studied of the aromatic amines reviewed in this Volume. Waste-water, air and urine samples have been analysed. The use of LC/MS and LC with electrochemical detection provides detection limits down to the nanomol level. ortho-Toluidine is one of the amines detected as a reduction product of azo dyes used as toy colourants. Table 1.1 presents selected methods of detection and quantification of ortho-toluidine in various matrices. Table 1.1. Selected methods of analysis of ortho-toluidine in various matrices Sample Sample preparation Assay method Detection limit Reference matrix Toys Sodium dithionite HPLC/UV 0.2 μg/g Garrigós et al.
  • Chemical Resistance List

    Chemical Resistance List

    Chemical Resistance List Resistance Substance Permeation Time/Level to Degradation Fluoro- natural chloro- nitrile/ nitrile carbon butyl latex prene chloroprene rubber NR CR CR NBR FKM IIR NR NR CR CR NBR NBR NBR NBR NBR FKM IIR IIR NBR NBR 395 450, 451 720, 722 717 727 730, 732 740, 741 743 754 764 890 897 898 chemical physical 403 706 723, 725 733, 836 742, 757 state 708 726 736 - 739 759 - 0 - 0 0 + 1-methoxy-2-propanol paste 4 2 2 3 4 4 B 1 3 4 6 6 - 0 - 0 0 + 1-methoxy-2-propyl acetate liquid 3 1 1 3 3 A B 2 3 6 6 - 0 0 - 0 + 1-methyl-2-pyrrolidone liquid 5 2 3 3 3 2 A B 1 3 3 6 6 - 0 + + + - 1,1,2-trichlorotrifluoroethane liquid 1 0 5 4 6 6 1 1 2 1 6 1 2 - - - - - - 1.2-epoxy ethane (ethylene oxide) liquid B A A A A 0 0 0 B 1 2 - - - - - - 1.2-epoxy propane (propylene oxide) liquid B A A A 1 A 0 0 0 B 1 2 + + + + + + 1.2-propanediol liquid 6 6 6 6 6 6 6 6 6 6 6 6 6 - + - + + 0 2-ethyl hexyl acrylate liquid 2 1 1 5 6 1 1 2 6 2 3 - 0 0 0 + + 2-mercaptoethanol liquid 3 2 4 4 4 4 1 1 3 6 6 6 - - - 0 0 - 2-methoxy-2-methyl propane liquid 1 B B 2 4 A 1 4 1 3 2 2 - - - - - 0 3-hexanone liquid 1 B 1 1 1 0 0 0 0 0 3 3 - - - - - 0 4-heptanone liquid 1 A 1 1 1 A 0 0 0 B 3 3 - - - - - + acetaldehyde liquid 1 1 1 1 B 0 0 0 A 0 6 6 0 0 0 - - + acetic acid anhydride liquid 6 3 3 3 3 2 A B 1 B 2 6 6 + + + + + + acetic acid, 10 % liquid 6 6 6 6 6 6 6 6 6 6 6 6 6 0 + + + + + acetic acid, 50 % liquid 5 4 6 6 6 2 4 6 6 6 6 - - - - 0 + acetic acid, conc.
  • Synthetic Turf Scientific Advisory Panel Meeting Materials

    Synthetic Turf Scientific Advisory Panel Meeting Materials

    California Environmental Protection Agency Office of Environmental Health Hazard Assessment Synthetic Turf Study Synthetic Turf Scientific Advisory Panel Meeting May 31, 2019 MEETING MATERIALS THIS PAGE LEFT BLANK INTENTIONALLY Office of Environmental Health Hazard Assessment California Environmental Protection Agency Agenda Synthetic Turf Scientific Advisory Panel Meeting May 31, 2019, 9:30 a.m. – 4:00 p.m. 1001 I Street, CalEPA Headquarters Building, Sacramento Byron Sher Auditorium The agenda for this meeting is given below. The order of items on the agenda is provided for general reference only. The order in which items are taken up by the Panel is subject to change. 1. Welcome and Opening Remarks 2. Synthetic Turf and Playground Studies Overview 4. Synthetic Turf Field Exposure Model Exposure Equations Exposure Parameters 3. Non-Targeted Chemical Analysis Volatile Organics on Synthetic Turf Fields Non-Polar Organics Constituents in Crumb Rubber Polar Organic Constituents in Crumb Rubber 5. Public Comments: For members of the public attending in-person: Comments will be limited to three minutes per commenter. For members of the public attending via the internet: Comments may be sent via email to [email protected]. Email comments will be read aloud, up to three minutes each, by staff of OEHHA during the public comment period, as time allows. 6. Further Panel Discussion and Closing Remarks 7. Wrap Up and Adjournment Agenda Synthetic Turf Advisory Panel Meeting May 31, 2019 THIS PAGE LEFT BLANK INTENTIONALLY Office of Environmental Health Hazard Assessment California Environmental Protection Agency DRAFT for Discussion at May 2019 SAP Meeting. Table of Contents Synthetic Turf and Playground Studies Overview May 2019 Update .....
  • EXPERIMENT 2 SEPARATION of a MIXTURE of P-TOLUIDINE AND

    EXPERIMENT 2 SEPARATION of a MIXTURE of P-TOLUIDINE AND

    EXPERIMENT 2 1:: SEPARATION OF A MIXTURE OF p-TOLUIDINE AND NAPHTHALENE BY SOLVENT EXTRACTION AND IDENTI- FICATION OF THEIR FUNCTIONAL GROUPS 4: 2.1 Introduction Objectives - 2.2 Principle 2.3 Requirements Identification of functional.groups 2.5 Result 2.1 INTROD-UCTION In the previous experiment you have separated a mixture containing two acidic and one neutral compound. The extracting solutions were aqueous bases. In this experiment you will be seperating a mixture of a basic and a neutral compound. As you will recall from sec. 1.2 of experiment 1 that this will require an aqueous'acidic solution. The basic compound after separation is recovered by re extraction. Objeetives After srudying and performing this experiment you should be able to : . separate a mixture of a neutral and a basic organic compound by solvent extraction technique, identify the functional group of the separated compounds, and describe the theory behind the above. 2.2 PRINCIPLE This mixture contains a basic compound, p-toluidine, and a neutral compound viz., naphthalene. Their separation is quite straight forward. You will recall from above that a basic compound can be extracted by an aqueous solution of an acid. As this mixture contains only one basic compound (as against two acidic compounds in the previous experiment), you don't need to bother about which acid to use for extraction. A strong acid like HCI is definitely a good choice and will afford an effective separation. The hydrochloric acid will convertp-toluidine into its hydrochloride salt which on extraction will moFVeinto aqueous layer. Separation of a Mixture of p-Toluidine and Naphthakne by Solvent Extraction and IdenH- Ucatkm dthelr FuaEtiooal C~P Q NII: HCI NI I,C'I- - + NH2 @-toluidine) @-tohidine hydrochldride) p-Toluidine Freep-toluidine can be recovered by hydrolping this salt with an aqueous base.
  • Synthesis of Densely Substituted Pyridine Derivatives from Nitriles by a Non-Classical [4+2] Cycloaddition/1,5-Hydrogen Shift Strategy

    Synthesis of Densely Substituted Pyridine Derivatives from Nitriles by a Non-Classical [4+2] Cycloaddition/1,5-Hydrogen Shift Strategy

    Synthesis of densely substituted pyridine derivatives from nitriles by a non-classical [4+2] cycloaddition/1,5-hydrogen shift strategy Wanqing Wu ( [email protected] ) South China University of Technology https://orcid.org/0000-0001-5151-7788 Dandan He South China University of Technology Kanghui Duan South China University of Technology Yang Zhou South China University of Technology Meng Li South China University of Technology Huanfeng Jiang South China University of Technology Article Keywords: pyridine derivatives, organic synthesis, medicinal chemistry. Posted Date: March 3rd, 2021 DOI: https://doi.org/10.21203/rs.3.rs-258126/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 1/18 Abstract A novel strategy has been established to assemble an array of densely substituted pyridine derivatives from nitriles and o-substituted aryl alkynes or 1-methyl-1,3-enynes via a non-classical [4 + 2] cycloaddition along with 1,5-hydrogen shift process. The well-balanced anities of two different alkali metal salts enable the C(sp3)-H bond activation as well as the excellent chemo- and regioselectivities. This protocol offers a new guide to construct pyridine frameworks from nitriles with sp3-carbon pronucleophiles, and shows potential applications in organic synthesis and medicinal chemistry. Introduction Compounds containing pyridine core structures, not only widely exist in natural products, pharmaceuticals, and functional materials,1–7 but also serve as useful and valuable building blocks for metal ligands.8,9 For instance, pyridine derivative Actos I10 is a famous drug for the treatment of type 2 diabetes; Bi-(or tri-)pyridines II11–15 are often used as ligands in metal-catalyzed reactions; Kv1.5 antagonist III16 and alkaloid papaverine IV17 are two representative isoquinolines as a promising atrial- selective agent and a smooth muscle relaxant, respectively (Fig.
  • 23.5 Basicity and Acidity of Amines

    23.5 Basicity and Acidity of Amines

    23_BRCLoudon_pgs5-0.qxd 12/8/08 1:22 PM Page 1122 1122 CHAPTER 23 • THE CHEMISTRY OF AMINES alkylamines, this resonance occurs at rather small chemical shift—typically around d 1. In aromatic amines, this resonance is at greater chemical shift, as in the second of the preceding examples. Like the OH protons of alcohols, phenols, and carboxylic acids, the NH protons of amines under most conditions undergo rapid exchange (Secs. 13.6 and 13.7D). For this reason, split- ting between the amine N H and adjacent C H groups is usually not observed. Thus, in the NMR spectrum of diethylamine,L the N H resonanceL is a singlet rather than the triplet ex- pected from splitting by the adjacent CHL2 protons. In some amine samples, the N H resonance is broadened and, like the OL H protonL of alcohols, it can be obliterated fromL the spectrum by exchange with D2O (the “DL2O shake,” p. 611). The characteristic 13C NMR absorptions of amines are those of the a-carbons—the carbons attached directly to the nitrogen. These absorptions occur in the d 30–50 chemical-shift range. As expected from the relative electronegativities of oxygen and nitrogen, these shifts are somewhat less than the a-carbon shifts of ethers. PROBLEMS 23.4 Identify the compound that has an M 1 ion at mÜz 136 in its CI mass spectrum, an IR 1 + = absorption at 3279 cm_ , and the following NMR spectrum: d 0.91 (1H, s), d 1.07 (3H, t, J 7Hz), d 2.60 (2H, q, J 7Hz), d 3.70 (2H, s), d 7.18 (5H, apparent s).
  • TR-470: Pyridine (CASRN 110-86-1) in F344/N Rats, Wistar Rats, And

    TR-470: Pyridine (CASRN 110-86-1) in F344/N Rats, Wistar Rats, And

    NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF PYRIDINE (CAS NO. 110-86-1) IN F344/N RATS, WISTAR RATS, AND B6C3F1 MICE (DRINKING WATER STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 March 2000 NTP TR 470 NIH Publication No. 00-3960 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health FOREWORD The National Toxicology Program (NTP) is made up of four charter agencies of the U.S. Department of Health and Human Services (DHHS): the National Cancer Institute (NCI), National Institutes of Health; the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health; the National Center for Toxicological Research (NCTR), Food and Drug Administration; and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention. In July 1981, the Carcinogenesis Bioassay Testing Program, NCI, was transferred to the NIEHS. The NTP coordinates the relevant programs, staff, and resources from these Public Health Service agencies relating to basic and applied research and to biological assay development and validation. The NTP develops, evaluates, and disseminates scientific information about potentially toxic and hazardous chemicals. This knowledge is used for protecting the health of the American people and for the primary prevention of disease. The studies described in this Technical Report were performed under the direction of the NIEHS and were conducted in compliance with NTP laboratory health and safety requirements and must meet or exceed all applicable federal, state, and local health and safety regulations. Animal care and use were in accordance with the Public Health Service Policy on Humane Care and Use of Animals.
  • Gasket Chemical Services Guide

    Gasket Chemical Services Guide

    Gasket Chemical Services Guide Revision: GSG-100 6490 Rev.(AA) • The information contained herein is general in nature and recommendations are valid only for Victaulic compounds. • Gasket compatibility is dependent upon a number of factors. Suitability for a particular application must be determined by a competent individual familiar with system-specific conditions. • Victaulic offers no warranties, expressed or implied, of a product in any application. Contact your Victaulic sales representative to ensure the best gasket is selected for a particular service. Failure to follow these instructions could cause system failure, resulting in serious personal injury and property damage. Rating Code Key 1 Most Applications 2 Limited Applications 3 Restricted Applications (Nitrile) (EPDM) Grade E (Silicone) GRADE L GRADE T GRADE A GRADE V GRADE O GRADE M (Neoprene) GRADE M2 --- Insufficient Data (White Nitrile) GRADE CHP-2 (Epichlorohydrin) (Fluoroelastomer) (Fluoroelastomer) (Halogenated Butyl) (Hydrogenated Nitrile) Chemical GRADE ST / H Abietic Acid --- --- --- --- --- --- --- --- --- --- Acetaldehyde 2 3 3 3 3 --- --- 2 --- 3 Acetamide 1 1 1 1 2 --- --- 2 --- 3 Acetanilide 1 3 3 3 1 --- --- 2 --- 3 Acetic Acid, 30% 1 2 2 2 1 --- 2 1 2 3 Acetic Acid, 5% 1 2 2 2 1 --- 2 1 1 3 Acetic Acid, Glacial 1 3 3 3 3 --- 3 2 3 3 Acetic Acid, Hot, High Pressure 3 3 3 3 3 --- 3 3 3 3 Acetic Anhydride 2 3 3 3 2 --- 3 3 --- 3 Acetoacetic Acid 1 3 3 3 1 --- --- 2 --- 3 Acetone 1 3 3 3 3 --- 3 3 3 3 Acetone Cyanohydrin 1 3 3 3 1 --- --- 2 --- 3 Acetonitrile 1 3 3 3 1 --- --- --- --- 3 Acetophenetidine 3 2 2 2 3 --- --- --- --- 1 Acetophenone 1 3 3 3 3 --- 3 3 --- 3 Acetotoluidide 3 2 2 2 3 --- --- --- --- 1 Acetyl Acetone 1 3 3 3 3 --- 3 3 --- 3 The data and recommendations presented are based upon the best information available resulting from a combination of Victaulic's field experience, laboratory testing and recommendations supplied by prime producers of basic copolymer materials.
  • MDI Process Update Process Economics Program Review 2016-13

    MDI Process Update Process Economics Program Review 2016-13

    ` IHS CHEMICAL MDI Process Update Process Economics Program Review 2016-13 March 2017 ihs.com PEP Review 2016-13 MDI Process Update Ron Smith Senior Principal Analyst Downloaded 20 March 2017 08:28 AM UTC by Anandpadman Vijayakumar, IHS ([email protected]) IHS Chemical | PEP Review 2016-13 MDI Process Update PEP Review 2016-13 MDI Process Update Ron Smith, Senior Principal Analyst Abstract Isocyanates are a major ingredient for the production of polyurethane products that are formed by the reactive polymerization of isocyanates with polyols. A long and difficult search for a reasonable economic pathway to produce isocyanates by vapor-phase phosgenation of diphenylmethane diamine (MDA) in place of liquid-phase phosgenation of MDA has been developed and commercialized since our last report on isocyanates (PEP Report 1E) was published in August 1992. In this review, we investigate large-scale, single-train integrated technology and economics for the production of methylene diphenyl diisocyanate (MDI), including condensation of aniline with formaldehyde to produce MDA, production of phosgene from carbon monoxide and chlorine, gas-phase phosgenation of MDA to produce crude MDI, and separation/recovery of MDI products. The key gas-phase phosgenation step produces isocyanates from MDA at high pressure and temperature, enabling a significant shortening of residence time in the reactor. The rate determining step is the dissociation of the polymeric MDA–carbonyl chloride intermediate into polymeric MDI and HCl followed by HCl removal. A summary of the process economics for the production of 373 million lbs/yr of crude MDI and 336 million lbs/yr of polymeric MDI (PMDI) and 37 million lbs/yr of pure MDI for continuous vapor-phase isocyanate production shows that on a US Gulf Coast basis, the world-scale, single-train, integrated vapor-phase technology–based plant will meet plant gate costs.