Antimicrobial activity of hydrophobic cotton coated with N‐halamine

γ‐(β‐Hydroxy‐γ‐5,5‐dimethylhydatoin)‐propyltriethoxysilane, a N‐halamine precursor, was synthesized with 3‐aminopropyltriethoxysilane and 3‐glycidyl‐5,5‐dimethylhydantoin. The N‐halamine precursor was tethered to the cotton fabric through ether linkages. The treated fabrics can be rendered excellent antimicrobial activity through a bleaching process. It can inactivate 100% of the Staphylococcus aureus and Escherichia coli O157:H7 with a contact time of 10 min and 30 min, respectively. Over 30% of the chlorine could be regained after the equivalent of 50 machine washes and rechlorination. The coatings resulted in a significant increase of hydrophobicity of cotton samples. In addition, the wrinkle recovery angle of the treated fabrics increased to some degree. Copyright © 2014 John Wiley & Sons, Ltd.     

Biocompatible antimicrobial cotton modified with tricarbimide‐based N‐halamine

Two N‐halamine precursors, 1‐glycidyl‐s‐triazine‐2,4,6‐trione and 1‐(2,3‐dihydroxypropyl)‐s‐triazine‐2,4,6‐trione, were synthesized and tethered onto cotton fabrics via the crosslinking agent 1,2,3,4‐butanetetracarboxylic acid. The modified samples were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The modified fabrics were rendered biocidal activities upon exposure to dilute hypochlorite solutions. The chlorinated cotton swatches were challenged with Staphylococcus aureus (ATCC 6538) and Escherichia coli O157:H7 (ATCC 43895) and exhibited excellent biocidal efficacy. The stability and rechargeability of the modified samples during washing and ultraviolet irradiation were also investigated. In vitro cell cytocompatibility studies demonstrated that the antibacterial cotton has good biocompatibility. Copyright © 2014 John Wiley & Sons, Ltd.     

Antibacterial poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) fibrous membranes containing quaternary ammonium salts

In this study, antimicrobial membranes based on biodegradable material poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) [P(3HB‐4HB)] and quaternary ammonium salts (QASs) by two methods have been performed. Three QASs with varied alkyl chain lengths have been synthesized successfully and characterized by ¹H nuclear magnetic resonance and Fourier transform infrared. The synthesized QASs were blended with P(3HB‐4HB) and electrospun into composite fibrous membranes or casted into conventional membranes. Electrospun fibrous membranes with large surface areas are a superior type of antimicrobial biomaterials, and they exhibit preferable properties than solution casting membranes. Specifically, electrospun fibrous membranes are tougher and can inactivate both Gram‐positive Staphylococcus aureus and Gram‐negative Escherichia coli O157:H7 in a contact time of 30 min, whereas the solution casting membranes cannot. The length of alkyl chain in the quaternary ammonium groups on the modified P(3HB‐4HB) membranes is able to influence the antimicrobial activity. This type of antimicrobial material may have potential applications in biomaterial field. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and characterization of flame‐retardant lamellar Mg(OH)2 thin films on citric acid‐treated cotton fabrics

Preparation and characterization of lamellar magnesium hydroxide (Mg(OH)₂) thin films on cotton fabrics are reported in this paper. Mercerized cotton fabrics were treated with citric acid, so carboxyl groups were introduced to the surface of the fabrics. Mg(OH)₂ seeds were first adsorbed on the citric acid‐treated cotton fabrics and then Mg(OH)₂ thin films grew on the fabric through secondary growth method. Kinetics and isotherm studies found that the adsorption of Mg(OH)₂ seeds on citric acid‐treated cotton fabrics followed pseudo second‐order kinetic model and Langmuir isotherm. This indicated that Mg(OH)₂ seeds adsorption was monolayer chemical adsorption driven by electric attraction between positively charged Mg(OH)₂ seeds and ? COO^? ions on the cotton fiber surface. The X‐ray diffraction (XRD) and SEM characterizations of the Mg(OH)₂ thin films covered cotton fabrics found that standing flaky Mg(OH)₂ crystals formed a shell of porous but continuous network on cotton fabric surface. Owing to the Mg(OH)₂ thin film covering, the fabric had fireproof property, lower thermal conductivity and higher optical absorbance in the UV, Vis and IR regions. Copyright © 2010 John Wiley & Sons, Ltd.     

Development of an environmentally friendly halogen‐free phosphorus–nitrogen bond flame retardant for cotton fabrics

A novel flame retardant diethyl 4‐methylpiperazin‐1‐ylphosphoramidate (CN‐3) containing phosphorous and nitrogen was prepared. Its chemical structure was confirmed by nuclear magnetic resonance (¹H‐, ¹³C‐, and ³¹P‐NMR), Fourier transform infrared spectroscopy, and elemental analysis. Print cloth and twill fabrics were treated with CN‐3 to achieve different levels of add‐on (7–22 wt% add‐ons for print cloth and 3–18 wt% add‐ons for twill). Thermogravimetric analysis, vertical flame test, and limiting oxygen index (LOI) were performed on the treated cotton fabrics and showed promising results. When the treated print cloth and twill fabric samples were tested using the vertical flame test (ASTM D6413‐08), we observed that the ignited fabrics self‐extinguished and left behind a streak of char. Treated higher add‐ons fabrics were neither consumed by flame nor produced glowing ambers upon self‐extinguishing. LOI (ASTM 2863–09) was used to determine the effectiveness of the flame retardant on the treated fabrics. LOI values increased from 18 vol% oxygen in nitrogen for untreated print cloth and twill fabrics to maximum of 28 and 31 wt% for the highest add‐ons of print cloth and twill, respectively. The results from cotton fabrics treated with CN‐3 demonstrated a higher LOI value as well as a higher char yield because of the effectiveness of phosphorus and nitrogen as a flame retardant for cotton fabrics. Furthermore, FT‐IR and SEM were used to characterize the chemical structure on the treated fabrics as well as the surface morphology of char areas of treated and untreated fabrics. Published 2012. This article is a US Government work and is in the public domain in the USA.     

Phase Behavior and Thermal Properties for Binary Blends of Bacterial Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)s with Narrow‐Comonomer‐Unit Compositional Distribution

The miscibility and the effect of compositional distribution on physical properties were investigated for binary blends of biosynthesized poly(3‐hydroxybutyrate) [P(3HB)] and comonomer compositionally fractionated poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)s [P(3HB‐co‐3HH)] with narrow compositional distribution. Biosynthesized P(3HB‐co‐3HH) samples were compositionally fractionated using solvent (chloroform)/nonsolvent (n‐heptane) mixtures. The binary blends of fractionated P(3HB‐co‐3HH)s with different 3HH unit content were prepared by casting from solution in chloroform. The miscibility and the thermal properties of these blends were analyzed by differential scanning calorimetry (DSC). It was found that the two components are miscible in the amorphous phase when the difference in 3HH unit content between the two component polymers of these blends is less than 20 mol‐%, subsequently they are immiscible when the difference is larger than 30 mol‐%. By comparing the thermal properties of the binary blends of fractions, with those for the fractions themselves, and with those for the bacterially as‐produced unfractionated copolyesters, the effects of compositional distribution on the properties of copolyesters were discussed.

Glass transition temperatures of blends PHB/H10, H10/H20, and PHB/H20 versus total 3HH unit content in the blends. The solid lines are the best fits of the experimental results of the P(3HB‐co‐3HH) fractions with narrow compositional distribution.     

A novel azocompound, 2‐(4‐phenylazoaniline)‐4‐phenylphenol: Spectroscopic and quantum‐chemical approach

A novel azocompound with two nonequivalents azo groups, 2‐(4‐phenylazoaniline)‐4‐phenylphenol, was synthesized and characterized by spectroscopic and computational analysis. An intramolecular hydrogen bonding (HB), ? O₁? H₁ ··· N₁? , involving the ? N₁?N₂? group and the proton in a neighbor hydroxyl moiety, was identified. It was found responsible for a characteristic π‐conjugated H₁? O₁? C₁₈?C₁₃? N₂?N₁? six‐membered cyclic fragment. It is worth noting that this azo group is involved in an azo‐hydrazo equilibrium, being the azo form the most stable one. This resonance‐assisted HB was characterized using the OH‐related infrared bands and the corresponding signals in ¹H NMR. In addition, conformational studies and geometrical and electronic parameter calculations were performed using the density functional theory, at B3LYP/6‐311++G** level. Bond and ring critical points were identified using the atoms in molecules theory, which allowed confirming the intramolecular HB. The second azo‐group cannot be involved in HB, but it also presents two stereoisomerics forms corresponding to cis (Z) and trans (E) configurations, with the later being the one with the lowest energy. © 2013 Wiley Periodicals, Inc.     

Processing of a Strong Biodegradable Poly[(R)‐3‐hydroxybutyrate] Fiber and a New Fiber Structure Revealed by Micro‐Beam X‐Ray Diffraction with Synchrotron Radiation

Summary: Biodegradable poly[(R)‐3‐hydroxybutyrate] (P(3HB)) fibers with high tensile strength of 1.32 GPa were processed from ultra‐high‐molecular‐weight P(3HB) by a method combining cold‐drawing and two‐step‐drawing procedures at room temperature. The distribution of molecular structures in a mono‐filament was analyzed by micro‐beam X‐ray diffraction with synchrotron radiation. It was revealed that the P(3HB) fiber has a new core‐sheath structure consistent with two types of molecular conformations: a 2₁ helix conformation in the sheath region and a planar zigzag conformation in the core region.

P(3HB) fiber processed by cold‐drawing in ice water and two‐step drawing at room temperature, and subsequently annealing at 50 °C.     

Blends of poly(3‐hydroxybutyrate)/4,4′‐thiodiphenol and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/ 4,4′‐thiodiphenol: Specific interaction and properties

The specific interaction between poly(3‐hydroxybutyrate) [P(3HB)] and 4,4′‐thiodiphenol (TDP) and between poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and TDP was investigated by Fourier transform infrared (FTIR) spectroscopy. Interassociated hydrogen bonds were found between the polyester chains and the TDP molecules in the binary blends. The fractions of associated carbonyl groups, F_b 's, in the blends first increased and then decreased as the TDP content increased. The thermal and dynamic mechanical properties of P(3HB)–TDP and PHBV–TDP blends were investigated by differential scanning calorimetry and dynamic mechanical thermal analysis, respectively. Thermal analysis revealed that the P(3HB)–TDP blends possessed eutectic phase behavior. Furthermore, it was found that the thermal and dynamic mechanical properties of P(3HB) and PHBV were greatly modified through blending with TDP. Environmental degradability in river water was evaluated by a biochemical oxygen demand tester, and it was clarified that TDP lowered the degradation rate of P(3HB). The results suggest that TDP is effective in modifying the physical properties as well as the biodegradability of polyesters. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2891–2900, 2000     

Synthesis of (4Z)‐4‐(Arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones by the Reaction of Ethyl (2Z)‐3‐Aryl‐2‐isothiocyanatoprop‐2‐enoates with Organolithium Compounds

A convenient one‐pot method for the preparation of (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones 2 and 3 from ethyl (2Z)‐3‐aryl‐2‐isothiocyanatoprop‐2‐enoates 1 , which can be easily prepared from ethyl 2‐azidoacetate and aromatic aldehydes, has been developed. Thus, these α‐isothiocyanato α,β‐unsaturated esters were treated with organolithium compounds, including lithium enolates of acetates, to provide 5‐substituted (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones, 2 , and 2‐[(4Z)‐(4‐arylmethylidene)‐5‐ethoxy‐2‐thioxo‐1,3‐oxazolidin‐5‐yl]acetates, 3 .     

Lipase‐Catalyzed Transformation of Unnatural‐Type Poly(3‐hydroxybutanoate) into Reactive Cyclic Oligomer

Unnatural‐type syndiotactic and atactic poly[(R,S)‐3‐hydroxybutanoate]s [P(3HB)s] were enzymatically transformed into a reactive cyclic 3HB oligomer of molecular weight ca. 500 in an organic solvent, such as toluene, using immobilized lipase from Candida antarctica at 40°C for 24 h. It was confirmed that similar results were obtained for both syndiotactic and atactic P(3HB)s. On the other hand, the acidic degradation of these polymers using a protonic acid, such as p‐toluenesulfonic acid, exclusively produced the linear 3HB oligomer instead of the cyclic oligomer. The formation of the cyclic oligomer was regarded as the characteristic feature of the lipase‐catalyzed degradation in organic media. The cyclic oligomer obtained readily reacted with alcohol as a nucleophile, and using lipase, to produce the alkyl ester of the 3HB oligomer.     

Studies on Binary Blends of Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) and Natural Polyphenol Catechin: Specific Interactions and Thermal Properties

The existence of a specific intermolecular hydrogen‐bonding interaction between poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) [P(3HB‐co‐3HH)] and (+)‐catechin in their blends was demonstrated by Fourier‐transform infrared spectroscopy (FT‐IR). It was found that the experimentally estimated fraction of hydrogen‐bonded carbonyl groups was much lower than the theoretically predicted maximum fraction. Only one glass transition temperature (T_g) occurred in the blends with the compositions detected by differential scanning calorimetry (DSC), being further confirmed by the results of dynamic mechanical thermal analysis (DMTA). The decrease of the melting point (T_m) and the increase of the glass transition temperature of the blends observed by the DSC measurements also suggested the existence of a strong intermolecular interaction. It was interesting to note that, as a low‐molecular‐weight compound, catechin showed a glass transition, which arises from strong self‐association. As expected, the crystalline structure of P(3HB‐co‐3HH) in the blends showed no change, but the crystallinity of the copolymer component in the blends, calculated by wide‐angle X‐ray diffraction, decreased with the increase of catechin weight content. Investigated by tensile experiments, the maximum strength and modulus decreased sharply with the increase of catechin content; on the contrary, the elongation changed slowly.

The FT‐IR spectra in the wave‐number 1 680–1 780 cm^?1 region for blends of P(3HB‐co‐3HH)/catechin. A: HBH; B: HBHC10; C: HBHC20; D: HBHC30; E: HBHC40; F: HBHC50; and G: catechin.     

Thermal and spectral stability of electroluminescent hyperbranched copolymers containing tetraphenylthiophene‐quinoline‐triphenylamine moieties

Fluorescent hyperbranched copolymers (HB‐x, x = 1–4) with inherent tetraphenylthiophene, triphenylamine (TPA) and quinoline (Qu) moieties were prepared to study the influence of the TPA branching point on the thermal and the spectral stability. All the HB‐x copolymers exhibited high glass transition temperatures (T_gs = 245–315 °C) with the detected values increasing with the increasing branching TPA content in the HB‐x. The solid HB‐x films possess high emission efficiency with the resulting quantum yields (?_Fs) in the ranges of 0.72–0.74. More importantly, the HB‐x copolymers and the derived light‐emitting devices exhibit high photoluminescence (PL) and electroluminescence (EL) stability towards thermal annealing at temperatures higher than 200 °C. After annealing at 200 °C (or 300 °C), no change was observed in the respective PL and EL spectra of HB‐1 (or HB‐4) copolymers. The spectral stability was found to correlate with T_g and with the highest branching density, HB‐4 copolymer possesses the highest thermal stability among all HB‐xs and show no EL spectral change after annealing at 300 °C for 4 h. The results indicate that all the branched HB‐x copolymers are promising candidates for the polymer light‐emitting diodes due to their high quantum yield and spectral stability. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Thermo‐ and pH‐responsive gradient and block copolymers based on 2‐(2‐methoxyethoxy)ethyl methacrylate synthesized via atom transfer radical polymerization and the formation of thermoresponsive surfaces

A series of gradient and block copolymers, based on 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO₂MA) and tert‐butyl acrylate (^tBA), were synthesized by atom transfer radical polymerization (ATRP) in a first step. The MEO₂MA monomer leads to the production of thermosensitive polymers, exhibiting lower critical solution temperature (LCST) at around room temperature, which could be adjusted by changing the proportion of ^tBA in the copolymer. In a second step, the tert‐butyl groups of ^tBA were hydrolyzed with trifluoroacetic acid to form the corresponding block and gradient copolymers of MEO₂MA and acrylic acid (AA), which exhibited both temperature and pH‐responsive behavior. These copolymers showed LCST values strongly dependent on the pH. At acid pH, a slightly decrease of LCST with an increase of AA in the copolymer was observed. However, at neutral or basic conditions, ionization of acid groups increases the hydrophilic balance considerably raising the LCST values, which even become not observable over the temperature range under study. In the last step, these carboxylic functionalized copolymers were covalently bound to biocompatible and biodegradable films of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) [P(HB‐co‐HHx)] obtained by casting and, previously treated with ethylenediamine (ED) to render their surfaces with amino groups. Thereby, thermosensitive surfaces of modified P(HB‐co‐HHx) could be obtained. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Bulk Gas‐Phase Acidity

The capability of a gaseous Brønsted acid HB to deliver protons to a base is usually described by the gas‐phase acidity (GA) value of the acid. However, GA values are standard Gibbs energy differences and refer to individual gas pressures of 1 bar for acid HB, base B^?, and proton H⁺. We show that the GA value is not suited to describe the bulk acidity of a gaseous acid. Here the pressure dependence of the activities of HB, H(HB)_n⁺, and B(HB)_m^? that result from gaseous autoprotolysis have to be considered. In this work, the pressure‐dependent absolute chemical potential of the proton in the representative gaseous proton acids CH₄, NH₃, H₂O, HF, and HCl was worked out and the general theory to describe bulk gas phase acidity—that can directly be compared with solution acidity—was developed.     

The comparison of differences in flammability and thermal degradation between cotton fabrics treated with phosphoramidate derivatives

The effectiveness of a phosphoramidate tetraethyl piperazine‐1,4‐diyldiphosphoramidate (TEPP) as a flame retardant on cotton twill fabrics was compared with that of a previously studied diethyl 4‐methylpiperazin‐1‐ylphosphoramidate (DEPP). TEPP was formed in a reaction between two phosphonates and a piperazine then cotton twill fabrics were treated with TEPP at different levels of add‐on (2–19 wt%) and characterized using vertical flammability, limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis methods. The results showed better flame retardancy and thermal behavior for TEPP fabrics when compared with DEPP fabrics. When the morphological structure of the formed char from the burned areas was examined by scanning electron microscopy, the results revealed a fairly insignificant difference in the mode of action between the two types of fabric. Copyright © 2014 John Wiley & Sons, Ltd.     

LC‐ESI‐MS/MS analysis and pharmacokinetics of heterophyllin B,a cyclic octapeptide from Pseudostellaria heterophylla in rat plasma

Heterophyllin B (HB) is a cyclic octapeptide isolated from Pseudostellaria heterophylla. HB is used as the quality control index for evaluating P. heterophylla in the Chinese Pharmacopoeia. A rapid and sensitive LC‐ESI‐MS/MS method was developed and validated for the analysis of HB in rat plasma. Sample preparation consisted of a solid‐phase extraction step for the removal of interference and preconcentration of the target analyte HB and the internal standard N‐acetylcysteine before chromatographic analysis by MS/MS detection. The separation of HB and N‐acetylcysteine was performed using a Hypersil GOLD^TM C₁₈ column and a mixture of methanol–water (60:40, v/v) containing 10 mmol/L ammonium formate and 0.1% formic acid as the mobile phase. The determination step was optimized in the selected reaction monitoring mode for the highly selective and sensitive quantitation of HB in rat plasma. Intra‐ and inter‐assay precision (as relative standard deviation) was ≤9.1%, and accuracy was between 92.6 and 102.7%. The validated method was successfully applied to quantify HB concentrations up to 7 h after tail intravenous injections of 2.08, 4.16 and 8.32 mg/kg HB in rats. The LC‐MS/MS method identified the relevant pharmacokinetic parameters of HB and its studied analog. Copyright © 2015 John Wiley & Sons, Ltd.     

Influence of multiple processing on selected properties of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)

The effect of multiple (up to 10 times) injection molding of processed poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P(3,4HB)) on its phase transition temperatures, degree of crystallinity, degradation temperature, mass flow rate, mechanical properties, dynamic mechanical properties, and Charpy's impact strength is presented. The studies have shown that the multiple injection lowers the degree of crystallinity and the thermal stability of P(3,4HB). The mass flow rate values increased with increasing the injection number. It was found that the multiple injections had no substantial effect on the tensile strength up to 10 injection cycles and the tensile strength at break, tensile strain at tensile strength, and tensile strain at break up to 6 injection cycles. The maximum value of storage modulus at 30 °C and impact strength were recorded for sample after 4 cycles of injection, while the values of storage modulus at 120 °C increased with increase of the injection cycles. Copyright © 2015 John Wiley & Sons, Ltd.     

Novel refreshable N‐halamine polymeric biocides containing imidazolidin‐4‐one derivatives

A novel cyclic‐amine monomer, 1‐acryloyl‐2,2,5,5‐tetramethylimidazolidin‐4‐one (ACTMIO), was synthesized in a good yield through the reaction of acryloyl chloride with 2,2,5,5‐tetramethylimidazolidin‐4‐one and was fully characterized with Fourier transform infrared and ¹H NMR studies. ACTMIO was copolymerized with several widely used acrylic and vinyl monomers under ordinary conditions. In the presence of triallyl‐1,3,5‐triazine‐2,4,6(1H,3H,5H)‐trione, ACTMIO was easily grafted onto most textile fabrics. After regular chlorine bleach treatment, N‐halamine derivatives of the corresponding polymeric materials exhibited antibacterial properties against Escherichia coli, and these properties were durable and refreshable with chlorine bleaching. The relationship between the structures and antibacterial properties of the samples is further discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3073–3084, 2001     

One‐Pot Syntheses of 2‐(2‐Sulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetic Acid Derivatives via Reactions of 3‐(2‐Isothiocyanatophenyl)prop‐2‐enoic Acid Derivatives with Thiols or Sodium Sulfide

Two efficient methods for the preparation of 2‐(2‐sulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetic acid derivatives 3 under mild conditions have been developed. The first method is based on the reaction of 3‐(2‐isothiocyanatophenyl)prop‐2‐enoates 1a – 1c with thiols in the presence of Et₃N in THF at room temperature, leading to the corresponding dithiocarbamate intermediates 2 , which underwent spontaneous cyclization at the same temperature by an attack of the S‐atom at the prop‐2‐enoyl moiety in a 1,4‐addition manner (Michael addition) to give 2‐(2‐sulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetates in one pot. The second method involves treatment of 3‐(2‐isothiocyanatophenyl)prop‐2‐enoic acid derivatives 1b – 1d with Na₂S leading to the formation of 2‐(2‐sodiosulfanyl‐4H‐3,1‐benzothiazin‐4‐yl)acetic acid intermediates 5 by a similar addition/cyclization sequence, which are then allowed to react with alkyl or aryl halides to afford derivatives 3 . 2‐(2‐Thioxo‐4H‐3,1‐benzothiazin‐4‐yl)acetic acid derivatives 6 can be obtained by omitting the addition of halides.