Gas-phase reaction of ozone with trans-2-hexenal,trans-2-hexenyl acetate,ethylvinyl ketone,and 6-methyl-5-hepten-2-one

The gas-phase reaction of ozone with the unsaturated oxygenates trans-2-hexenal, trans-2-hexenyl acetate, ethylvinyl ketone, and 6-methyl-5-hepten-2-one, which are components of biogenic emissions and/or close structural homologues thereof, has been investigated at atmospheric pressure and ambient temperature (286–291 K) and humidity (RH = 55 ± 10%). Reaction rate constants, in units of 10⁻¹⁸ cm³ molecule⁻¹ s⁻¹, are 1.28 ± 0.28 for trans-2-hexenal, 21.8 ± 2.8 for trans-2-hexenyl acetate, and 394 ± 40 for 6-methyl-5-hepten-2-one. Carbonyl product formation yields, measured with sufficient cyclohexane added to scavenge the hydroxyl radical, are 0.53 ± 0.06 for n-butanal and 0.56 ± 0.04 for glyoxal from trans-2-hexenal, 0.47 ± 0.02 for n-butanal and 0.58 ± 0.14 for 1-oxoethyl acetate from trans-2-hexenyl acetate, 0.55 ± 0.07 for formaldehyde and 0.44 ± 0.03 for 2-oxobutanal from ethylvinyl ketone, and 0.28 ± 0.02 for acetone from 6-methyl-5-hepten-2-one. Reaction mechanisms are outlined and the atmospheric persistence of the compounds studied is briefly discussed. © 1996 John Wiley & Sons, Inc.     

Kinetics of the reactions of O3 and OH radicals with a series of dialkenes and trialkenes at 294 ± 2 K

Rate constants for the gas phase reactions of O₃ and OH radicals with 1,3-cycloheptadiene, 1,3,5-cycloheptatriene, and cis- and trans-1,3,5-hexatriene and also of O₃ with cis-2,trans-4-hexadiene and trans -2,trans -4-hexadiene have been determined at 294 ± 2 K. The rate constants determined for reaction with O₃ were (in cm³ molecule^-1s^?1 units): 1,3-cycloheptadiene, (1.56 ± 0.21) × 10^-16; 1,3,5-cycloheptatriene, (5.39 ± 0.78) × 10^?17; 1,3,5-hexatriene, (2.62 ± 0.34) × 10^?17; cis?2,trans-4-hexadiene, (3.14 ± 0.34) × 10^?16; and trans ?2, trans -4-hexadiene, (3.74 ± 0.61) × 10^?16; with the cis- and trans-1,3,5-hexatriene isomers reacting with essentially identical rate constants. The rate constants determined for reaction with OH radicals were (in cm³ molecule^?1 s^?1 units): 1,3-cycloheptadiene, (1.31 ± 0.04) × 10^?10; 1,3,5-cycloheptatriene, (9.12 × 0.23) × 10^?11; cis-1,3,5-hexatriene, (1.04 ± 0.07) × 10^?10; and trans 1,3,5-hexatriene, (1.04 ± 0.17) × 10^?10. These data, which are the first reported values for these di- and tri-alkenes, are discussed in the context of previously determined O₃ and OH radical rate constants for alkenes and cycloalkenes.     

Rate constants for the gas-phase reactions of cis-3-Hexen-1-ol,cis-3-Hexenylacetate,trans-2-Hexenal,and Linalool with OH and NO3 radicals and O3 at 296 ± 2 K,and OH radical formation yields from the O3 reactions

Rate constants for the gas-phase reactions of the four oxygenated biogenic organic compounds cis-3-hexen-1-ol, cis-3-hexenylacetate, trans-2-hexenal, and linalool with OH radicals, NO₃ radicals, and O₃ have been determined at 296 ± 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained were (in cm³ molecule^?1 s^?1 units): cis-3-hexen-1-ol: (1.08 ± 0.22) × 10^?10 for reaction with the OH radical; (2.72 ± 0.83) × 10^?13 for reaction with the NO₃ radical; and (6.4 ± 1.7) × 10^?17 for reaction with O₃; cis-3-hexenylacetate: (7.84 ± 1.64) × 10^?11 for reaction with the OH radical; (2.46 ± 0.75) × 10^?13 for reaction with the NO₃ radical; and (5.4 ± 1.4) × 10^?17 for reaction with O₃; trans-2-hexenal: (4.41 ± 0.94) × 10^?11 for reaction with the OH radical; (1.21 ± 0.44) × 10^?14 for reaction with the NO₃ radical; and (2.0 ± 1.0) × 10^?18 for reaction with O₃; and linalool: (1.59 ± 0.40) × 10^?10 for reaction with the OH radical; (1.12 ± 0.40) × 10^?11 for reaction with the NO₃ radical; and (4.3 ± 1.6) × 10^?16 for reaction with O₃. Combining these rate constants with estimated ambient tropospheric concentrations of OH radicals, NO₃ radicals, and O₃ results in calculated tropospheric lifetimes of these oxygenated organic compounds of a few hours. © 1995 John Wiley & Sons, Inc.     

Study of thermal decomposition of poly-(vinyl chloride)-type polymers with the use of model substances-V: Pyrolysis of cis-5-chloro-3-heptene and cis- and trans-5-acetoxy-3-heptene in the phase

The gas phase pyrolyses of cis-5-chloro-3-heptene (in the range 267–337°) and cis- and trans-5-acetoxy-3-heptene (300–378°) are homogeneous unimolecular first-order reactions with rate constants given respectively by: log k = (12·03 = 0·13) - (36·2 ± 0·4)/2·303 RT and (12·80 ± 0·11) - (43·0 ± 0·3)/2·303 RT. (Frequency factors in sec^?1 units, activation energies in kcal mol^?1.) No significant differences were found between the rates of decomposition of cis and trans isomers of 5-acetoxy-3-heptene. From the decomposition of these models of poly(vinyl chloride) and poly(vinyl acetate), some conclusions about the role of internal unsaturated groups in the thermal decomposition of both polymers were drawn. The possibility that groups with cis internal double bonds are the most labile structures in a poly(vinyl) chloride macromolecule is discussed.     

Electrocyclic reactions of tetraenes: Influence of terminal substituents

Conjugated tetraenes with both central double bonds of cis configuration undergo a series of thermal reactions, the observable products being markedly dependent on the nature of the terminal substituents. Dimethyl 2E,4Z,6Z,8E-decatetraene-1,10-dioate (16) was prepared and found to cyclize readily at 50° to trans dimethyl 2,4-bicyclo[4.2.0)octadiene-6,7-dicarboxylate (18). This reaction proceeds to equilibrium, and the rates and equilibrium constants at the indicated temperatures are: 3.0 × 10^-5 sec^-1 ?40°; 8.2 × 10^-5 sec^-1, 16.0,50°; ?10.0,75°; ?7.47,100° with the equilibrium favoring (18). A sample of 1,8-diphenyl-1E,3Z,5Z;7E-octatetraene (1) showed no reaction below 120°, and at 175° all trans 1,8-diphenyl-octatetraene, cis and trans stilbenes, trans-5-phenyl-6(cis-styryl)-1,3-cyclohexadiene cis-5-phenyl-6-(trans-styryl)-1,3-cyclohexadiene, and cis and trans 6,8-diphenyl-tricyclo[3.2.1.0^2.7]oct-3-enes were formed. At 100° in the presence of excess dimethyl acetylenedicarboxylate 1 gave dimethyl trans-3,4-diphenyltricyclo[4.2.2.0^2.5]deca-6,9-dien-6,7-dicarboxylate. Finally 1,4-di(1-cyclohexen-1-yl)-1,3-batadiyne, hydrogenated over a Lindlar catalyst, gave only tricyclo[10.4.0.0^6,11]hexadeca-1,3,5-triene.     

Kinetics of the gas-phase reactions of Cl atoms with chloroethenes at 298 ± 2 K and atmospheric pressure

Using a relative rate technique, rate constants have been determined for the gas-phase reactions of Cl atoms with the cholorethenes and ethane at 298 ± 2 K and 735 torr total pressure of air. Using a rate constant of 1.97 × 10^?10 cm³ molecule^?1 s^?1 for the reaction of Cl atoms with n-butane, the following rate constants (in units of 10^?11 cm³ molecule^?1 s^?1) were obtained: vinyl chloride, 12.7 ± 0.2; 1,1-dichloroethene, 14.0 ± 0.2; cis-1,2-dichloroethene, 9.65 ± 0.10; trans-1,2-dichloroethene, 9.58 ± 0.18; trichloroethene, 8.08 ± 0.10; tetrachloroethene, 4.13 ± 0.23; and ethane, 6.17 ± 0.08 (where the indicated error limits do not include the uncertainties in the rate constant for n-butane). A small amount of cis-trans isomerization was observed for the reactions involving the cis- and trans-1,2-dichloroethenes. These data are compared and discussed with the available literature data.     

Cis–trans isomerization and spin multiplicity dependences on the static first hyperpolarizability for the two-alkali-metal-doped saddle[4]pyrrole compounds

Doping two alkali-metal atoms (Li and Na) into the saddle-shaped saddle[4]pyrrole forms four new two-alkali-metal-doped compounds with alkalide or electride characteristic. They are cis-LiNa(saddle[4]pyrrole) isomers 1(singlet) and 2(triplet), and trans-Li(saddle[4]pyrrole)Na isomers 3(singlet) and 4(triplet). The four structures with all-real frequencies are obtained at the density functional theory (DFT) B3LYP/6-311+G(d) level. All calculations of electric properties have been carried out at the second order Møller–Plesset perturbation theory (MP2) level. The order of the β ₀ values is 3.54 × 10³ for trans-4(triplet) <1.51 × 10⁴ for cis-1(singlet) <3.57 × 10⁴ for cis-2(triplet) <2.34 × 10⁵ a.u. for trans-3(singlet). The static first hyperpolarizability (β ₀) depends on the cis–trans isomerization and spin multiplicity. The result demonstrates that the cis–trans isomerization and spin multiplicity controls of the second-order NLO response are possible.     

Reactivity of the 5-hexenyl radical toward the anion of 2-nitropropane and borohydride anion

The 5-hexenyl radical adds to the anion of 2-nitropropane with a rate constant of ≈ × 10⁶ L/mol-s at 40°. Hydrogen atom abstraction from BH₄^? occurs more slowly than abstraction from CH₃O^? and with a rate constant less than 1 × 10⁴ L/mol-s at 30°. The reaction of Δ⁵- hexenylmercury chloride with sodium borohydride in MeOH/NaOH proceeds via hydrogen abstraction by the hexenyl radical from RHgH and not from NaBH₄.     

Quenching of biacetyl (3Au) molecules by near-resonant and off-resonant collisional partners

Laser-induced time-resolved phosphorescence has been used to evaluate the quenching of gaseous biacetyl (³A_u) molecules by various molecules at 25°C. The quenching of biacetyl (³A_u) molecules by biacetyl itself was not detectable under our experimental conditions, and a pressure-independent lifetime of 1.70 ± 0.08 msec was found. The bimolecular rate constants (units of l/mol·sec) for quenching of the ³A_u molecules by cis-2-pentene, trans-2-pentene, cis-1,3-pentadiene, trans-1,3-pentadiene, and oxygen were found to be (3.3 ± 1.9) × 10³, (4.0 ± 0.2) × 10⁴, (3.9 ± 0.1) × 10⁸, (1.3 ± 0.1) × 10⁸, and (5.2 ± 0.4) × 10⁸, respectively.     

Fast Analysis of Synthetic Pyrethroid Metabolites in Water Samples Using In-Syringe Derivatization Coupled Hollow Fiber Mediated Liquid Phase Microextraction with GC-ECD

A fast and efficient method has been demonstrated for the trace determination of six important metabolites of synthetic pyrethroids including cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis- and trans-Cl₂CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Br₂CA), 4-fluoro-3-phenoxybenzoic acid (4-F-3-PBA), 3-phenoxybenzoic acid (3-PBA), and 2-phenoxybenzoic acid (2-PBA) in environmental water samples using hollow fiber (HF)-mediated liquid-phase microextraction (LPME) coupled with in-syringe derivatization (ISD) followed by gas chromatography (GC) with electron capture detector (ECD) analysis. This method utilizes a HF membrane segment impregnated with extraction solvent as the LPME sampling probe, which was connected to a microsyringe pre-filled with derivatizing agents, and it was immersed into sample solution for extraction. After extraction, the extracting solution was subjected to derivatization reaction that was performed inside the syringe barrel followed by GC-ECD analysis. Under optimal conditions, the best extraction efficiency was obtained using sampling probe (2.0 cm hollow fiber) impregnated with 1-octanol immersed into water sample (5.0 mL, adjusted pH below 1.0) and stirring (1,250 rpm) for 10 min at 70 °C and diisopropylcarbodiimide (2 μL) and 1,1,1,3,3,3-hexafluoro-2-propanol (1 μL) were the derivatizing agents used. The detection limits of 3 ng mL^?1 for cis- and trans-Cl₂CA, 2 ng mL^?1 for cis-Br₂CA, 6 ng mL^?1 for 4-F-3-PBA, and 0.6 ng mL^?1 for 3-PBA and 2-PBA. The method showed good linearity (R ² = 0.973?0.998), repeatability from 4.0 to 13 % (n = 5), recovery from 79.2 to 95.7 %, and enrichment factors ranged between 109 and 159 for target analytes spiked in water samples. The proposed method and conventional methods were compared. Results suggested that the proposed HF-LPME-ISD/GC-ECD method was a rapid, simple, inexpensive, and eco-friendly technique for the analysis of metabolites of pyrethroids.     

Kinetics of the gas-phase reactions of NO3 radicals with a series of alkynes,haloalkenes, and α,β-unsaturated aldehydes

Rate constants for the gas-phase reactions of NO₃ radicals with a series of alkynes, haloalkenes, and α,β-unsaturated aldehydes have been determined at 298 ± 2 K using a relative rate technique. Using rate constants for the reactions of NO₃ radicals with ethene and propene of (1.1 ± 0.5) × 10^?16 cm³ molecule^?1 s^?1 and (7.5 ± 1.6) × 10^?15 cm³ molecule^?1 s^?1, respectively, the following rate constants (in units of 10^?16 cm³ molecule^?1 s^?1) were obtained: acetylene, ≤0.23; propyne, 0.94 ± 0.44; vinyl chloride, 2.3 ± 1.1; 1,1-dichloroethene, 6.6 ± 3.1; cis-1,2-dichloroethene, 0.75 ± 0.35; trans-1,2-dichloroethene, 0.57 ± 0.27; trichloroethene, 1.5 ± 0.7; tetrachloroethene, <0.4; allyl chloride, 2.9 ± 1.3; acrolein, 5.9 ± 2.8; and crotonaldehyde, 41 ± 9. The atmospheric implications of these data are discussed.     

The SO2(3B1) photosensitized isomerization of cis- and trans-1,2-dichloroethylene

The photolysis of SO₂ at 3712 Å in the presence of the 1,2-dichloroethylenes has been investigated at 22deg;C. The data are consistent with the SO₂(³B₁) photosensitized isomerization of the 1,2-dichloroethylene isomer. A kinetic treatment of the initial quantum yield data was consistent with the formation of a polarized charge-transfer intermediate whenever SO₂(³B₁) molecules and one of the 1,2-dichloroethylene isomers collide which ultimately decays unimolecularly to the cis-isomer with a probability of 0.70 ± 0.26 and to the trans-isomer with a 0.37 ± 0.16 probability. Quenching rate constants for removal of SO₂(³B₁) molecules by cis- and trans-1,2-dichloroethylene have been estimated from quantum yield data and from laser excited phosphorescence lifetimes using an excitation wavelength of 3130 Å. Estimates of the quenching rate constant (units of 1./mole ± sec) are for the cis-isomer, (1.63 ± 0.71) × 10¹⁰, quantum yield data, and (2.44 ± 0.11) × 10¹⁰, lifetime data; and for the trans-isomer,(2.59 ± 0.09)×10¹⁰, lifetime data, and (2.35 ±0.89) × 10¹⁰, quantum yield data. An experimentally determined photostationary composition,[cis-C₂Cl₂H₂]/[trans-C₂Cl₂H₂] = 1.8 - 0.1, was in good agreement with a value of 2.00 - 1.15 which was predicted from rate constants derived in this study.     

Halide‐Anion Binding by Singly and Doubly N‐Confused Porphyrins

The halide‐binding properties of N‐confused porphyrin (NCP, 1 ) and doubly N‐confused porphyrins (trans‐N₂CP ( 2 ), cis‐N₂CP ( 3 )) were examined in CH₂Cl₂. In the free‐base forms, cis‐N₂CP ( 3 ) showed the highest affinity to each anion (Cl^?, Br^?, I^?) with association constants K_a=7.8×10³, 1.9×10³, and 5.8×10² M ^?1, respectively. As metal complexes, on the other hand, trans‐N₂CP 2–Cu exhibited the highest affinity to Cl^?, Br^?, and I^? with K_a=9.0×10⁴, 2.7×10⁴, and 1.9×10³ M ^?1, respectively. The corresponding K_a values for cis‐N₂CP 3–Cu and NCP 1–Cu were about 1/10 and 1/2, respectively, of those of 2–Cu . With the help of density functional theory (DFT) calculations and complementary affinity measurements of a series of trisubstituted N‐confused porphyrins, the efficient anion binding of NCPs was attributed to strong hydrogen bonding at the highly polarized NH moieties owing to the electron‐deficient C₆F₅ groups at meso positions as well as the ideally oriented dipole moments and large molecular polarizability. The orientation and magnitude of the dipole moments in NCPs were suggested to be important factors in the differentiation of the affinity for anions.     

Secondary reactions in controlled potential coulometry: Part V. Reversal coulometric study of the reduction of cis- and trans-thioindigo in the presence of carbon dioxide,cinnamonitrile and acrylonitrile

Controlled potential reversal coulometry was applied to the following systems: (I) C+neR; R+C → RC; RC+ne → products. (II) as in (I) except RC not electroactive. (III) C+neR; R+X → RX; RX+ne → products. Equations for these e.c.e. and e.c. mechanisms were obtained and solved numerically. Working curves are presented for the calculation of the rate constants of the homogeneous reactions. This treatment was applied to studies of the reduction of thioindigo (TI) alone and in the presence of several reactants. For TI alone the reaction mechanism involves reaction of the radical anion (TI^?_·) with parent molecule followed by a second electron transfer. In the presence of excess dissolved CO₂, acrylonitrile (AN), or cinnamonitrile (CN), reaction of TI^?_· with these followed by a second electron transfer was proposed. Rate constants for the TI?TI^?_· coupling reaction were 82 (cis-thioindigo), and 323 (trans-thioindigo) l mol^?1 s^?1; pseudo-first-order reactions of TI^?_· were 0.016 (trans-) and 0.047 (cis-) s^?1 with CO₂; 0.023 (trans-) and 0.033 (cis-) s^?1 with CN; 0.022 (trans-) and 0.032 (cis-) s^?1 with AN.     

The synthesis and photochemical properties of amphiphilic phenylazonaphthalenes

Three novel amphiphilic phenylazonaphthalenes, namely, 6-(4-(4-octylphenylazo)naphthoxy)hexanoic acid, 6-(4-(4-dodecylphenylazo)naphthoxy)hexanoic acid, 6-(4-(4-hexadecylphenylazo)naphthoxy)hexanoic acid, were synthesized by diazo coupling, etherification and hydrolysis reactions successively. The kinetic studies of the trans–cis isomerization indicated that about 95% of the trans isomers of these compounds in chloroform solutions were transformed to cis isomers under the irradiation of near-ultraviolet light (380±30 nm) observed from UV–Vis spectra. In the dark condition, the cis isomers could reversibly convert to trans isomers following the first-order kinetics at the rates of 4.9×10^-4, 5.7×10^-4, 7.7×10^-4 S^-1, respectively.     

Electronic spectra of the isomeric 4-benzylidene-2-phenyl-Δ2-oxazolin-5-ones and the products of their reaction with nucleophiles including α-chymotrypsin : Kinetics of the hydrolysis of the isomeric enzyme derivatives

The 4-cis- and trans-benzylidene-2-phenyl-Δ²oxazolin-5-ones have been prepared and evaluated as chromophoric reagents for the investigation of the active site of α-chymotrypsin. The UV spectra of the isomeric oxazolinones are discussed and compared with those of similar compounds, notably the 1,4-diphenyl-1,3-butadienes, A novel spectroscopic consequence of geometrical isomerism in conjugated chromophores is reported. The facile isomerization of the cis-oxazolinone has been investigated by spectrophotometry and product isolation. Both oxazolinones react rapidly with the enzyme to provide products whose UV spectra are consistent with their assignment as α-benzamido- cinnamoyl-enzymes. The uncertainties in these assignments resulting from the presence in the oxazolinones of multiple electrophilic centres are discussed. The pseudo first-order rate constants for the hydrolysis of the products of interaction of α-chymotrypsin with the isomeric oxazolinones were determined at 25·0°, I = 00·1 in the pH range 7–10–5. The pH-rate profile for the hydrolysis of the product formed by reaction of the trans-oxazolinone is consistent with this reaction being deacylation of α-benzamido-trans-cinnamoyl-α-chymotrypsin catalysed by the enzyme's electron relay system (pKa 7·8, ks= 0·159s^?1). The pH rate profile for the hydrolysis of the product formed by reaction of the cis-oxazolinone is more complex. The profile could include a component catalysed by the relay system (pKa approx 8, $\text{k}$, = 10^?3 s^?1) but the predominating reaction appears to be an unusually rapid reaction of the derivatized enzyme with hydroxide ion (k = 233 ± 10 M^?1s^?1). Possible interpretations of these pH-rate profiles are discussed.     

A relative rate study of the reaction of bromine atoms with a variety of organic compounds at 295 K

The relative rate technique has been used to determine rate constants for the reaction of bromine atoms with a variety of organic compounds. Decay rates of the organic species were measured relative to i-butane or acetaldehyde or both. Using rate constants of 1.74 × 10^?15 and 3.5 × 10^?12 cm³ molecule^?1 s^?1 for the reaction of Br with i?butane and acetaldehyde respectively, the following rate constants were derived, in units of cm³ molecule^?1 s^?1: 2, 3?dimethylbutane, (6.40 ± 0.77) × 10^?15; cyclopentane, (1.16 ± 0.18) × 10^?15, ethene, (≤2.3 × 10^?13); propene, (3.85 ± 0.41) × 10^?12; trans-2-butene, (9.50 ± 0.76) × 10^?12, acetylene, (5.15 ± 0.19) × 10^?15; and propionaldehyde, (9.73 ± 0.91) × 10^?12. Quoted errors represent 2σ and do not include possible systematic errors due to errors in the reference rate constants. Experiments were performed at 295 ± 2 K and atmospheric pressure of synthetic air or nitrogen. The results are discussed with respect to the mechanisms of these reactions and their utility in serving as a laboratory source of alkyl and alkyl peroxy radicals.     

Long branching in poly(vinyl acetate) and poly(vinyl alcohol). III. Kinetic study of the branching reaction in the radical polymerization of vinyl acetate

The branching reaction in the radical polymerization of vinyl acetate was studied kinetically. Branching occurs by polymer transfer as well as terminal double-bond copolymerization. The chain-transfer constants to the main chain (C_p,2) and to the acetoxy methyl group (C_p,1) on the polymer were calculated on the basis of the experimental data described in the preceding paper giving C_p,2 = 3.03 × 10^?4, C_p,1 = 1.27 × 10^?4 at 60°C, and C_p,2 = 2.48 × 10^?4, C_p,1 = 0.52 × 10^?4 at 0°C. Chain transfer to monomer is important with respect to the formation of the terminal double bond. The total values of transfer constants to the α- or β-position in the vinyl group and the acetoxymethyl group in vinyl acetate was determined to be 2.15 × 10^?4 at 60°C. The transfer constant to the acetyl group in the monomer (C_m,1) was also evaluated to be 2.26 × 10^?4 at 60°C from the quantitative determination of the carboxyl terminals in PVA. These facts suggest that the chain-transfer constant to the α- or β-position in the monomer (C_m,2) is nearly equal to zero within experimental error. Copolymerization reactivity parameters of the terminal double bond were also estimated. In conclusion, it has become clear that the formation of nonhydrolyzable branching by the terminal double-bond reaction can be almost neglected, and hence that the long branching in PVA is formed only by the polymer transfer mechanism. On the other hand, a large number of hydrolyzable branches in PVAc are prepared by the terminal double-bond reaction rather than by polymer transfer.     

Starch cellulose acetate co-acrylate (SCAA) polymer as a drug carrier

The present study aims to create a controlled-release system through the preparation and characterization of starch cellulose acetate co-acrylate (SCAA) polymer for application as a carrier for cancer drugs. SCA was prepared from maize starch and different ratios of cellulose acetate. The obtained product SCA was reacted with acrylic acid monomer to give cellulose acetate co-acrylate. The best ratio of starch to cellulose acetate was found to be 90:10, giving a stable product with acrylic acid. The cancer drug 8-(2-methoxyphenyl)-3,4-dioxo-6-thioxo-3,4,6,7-tetrahydro-2h-pyrimido[6,1-c]-[1,2,4]triazine-9-carbonitrile was dissolved in dimethylformamide then added gradually at the end of the previous reaction under stirring for 15 min. The prepared polymers with and without the drug were characterized by Fourier-transform infrared spectroscopy. Cuboids discs of the prepared polymer/drug were subjected to drug release in aqueous media at different pH values. The release was measured spectrophotometrically. It was found that the release rate depends on the pH of the aqueous medium as well as on the concentration of the drug loaded onto the polymer carrier. Above pH 12, the polymer containing the drug degraded completely within 1 h after being subjected to alkaline media. Sustained release of drug extended to about 20 days. The amount released depended on the pH of the media in the following order: basic media > acidic media > neutral. According to Higuch’s equation, the diffusion coefficient was found to be 4.2 × 10^?8 and 5.5 × 10^?8 cm s^?1 for the two evaluated concentrations (1.5 and 2 %) of active organic compound (drug).