Novel Rearrangement During Alkaline Hydrolysis of 1,1,1-Trichloro-2-alken-4-ones

1972 ◽  
Vol 50 (16) ◽  
pp. 2561-2567 ◽  
Author(s):  
Eberhard Kiehlmann ◽  
B. C. Menon ◽  
J. I. Wells
Keyword(s):  
Methyl Ester ◽  
Potassium Hydroxide ◽  
Potassium Salt ◽  
Dienoic Acid ◽  
Equimolar Amount ◽  
Hydrogen Atoms ◽  
Alkaline Methanolysis ◽  
Pentadienoic Acid ◽  
Hydrolysis Of ◽  
Fold Excess

The action of a five-fold excess of potassium hydroxide in methanol on 1,1,1-trichloro-2-penten-4-one (1), 1,1,1-trichloro-6-methyl-2-hepten-4-one (5), and 1,1,1-trichloro-6,6-dimethyl-2-hepten-4-one (9) gives rise to the potassium salt of 5-chloro-2,4-pentadienoic acid (2), the potassium salt and methyl ester of 5-chloro-6-methyl-2,4-heptadienoic acid (7), and the methyl ester of 5-chloro-6,6-dimethyl-2,4-heptadienoic acid (10), respectively.When the same reaction is performed with an equimolar amount of base, 1 is converted into methyl 5-chloro-2,4-pentadienoate (3) as well as 1,1,1-trichloro-2-methoxy-4-pentanone (4); the latter compound (4) is shown to be a true intermediate in the formation of 3.Neither 1,1,1-trichloro-5-methyl-2-hexen-4-one (11) nor 1,1,1-trichloro-5-ethyl-2-hepten-4-one (14) yields the expected dienoic acid or ester when treated with an equimolar amount of potassium hydroxide. Instead, alkaline methanolysis of 11 leads to the formation of a mixture of 1,1,1-trichloro-2-methoxy-5-methyl-4-hexanone (12) and 1,1-dichloro-2,5-dimethoxy-5-methyl-4-hexanone (13), whereas 14 gives predominantly 1,1,1-trichloro-2-methoxy-5-ethyl-4-heptanone (15) and traces of 1,1-dichloro-2,5-dimethoxy-5-ethyl-4-heptanone (16).On the basis of these observations, a mechanism is proposed for the formation of 2, 7, and 10 which requires the presence of two geminal α-hydrogen atoms in the olefinic starting material.

Variation in Quantity of Methanol Recovered from Raisins

1963 ◽  
Vol 46 (2) ◽  
pp. 341-343
Author(s):  
M Alice Brown ◽  
James R Woodward ◽  
Floyd DeEds
Keyword(s):  
Methyl Ester ◽  
Esterase Activity ◽  
Enzymic Hydrolysis ◽  
Methanol Content ◽  
Naturally Occurring ◽  
Pectin Esterase ◽  
Hydrolysis Of

Abstract The amount of naturally occurring methanol in fruit must be known so that the quantity left as fumigation residue can be determined. In a study of methanol content of raisins, which had given inconsistent results, the raisins were subjected to different conditions of treatment immediately prior to methanol determination. Conditions that favored pectin esterase activity gave higher values for methanol content than conditions known to inactivate enzymes. Evidence was also obtained that both chemical and enzymic hydrolysis of methyl ester groups of pectic materials occur during analysis.

Preparation and structural analysis of (±)-threo-ritalinic acid

2013 ◽  
Vol 69 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Sara Wyss ◽  
Irmgard A. Werner ◽  
W. Bernd Schweizer ◽  
Simon M. Ametamey ◽  
Selena Milicevic Sephton
Keyword(s):  
Methyl Ester ◽  
Free Acid ◽  
Nmr Analysis ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ph Values ◽  
Ritalinic Acid ◽  
Methyl Phenidate ◽  
Hydrolysis Of

Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield,viz.(±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to theP21/nspace group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC—)CH—CHpygroup (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negativegauche+–gauche−interactions.

Hidrolisis minyak biji asam jawa (tamarindus indica linn) menjadi asam lemaknya dan uji aktivitas antibakteri

2021 ◽  
Vol 2 (2) ◽  
pp. 100-104
Author(s):  
Arnanda Dhafin Rizky ◽  
Sutrisno Sutrisno ◽  
Parlan Parlan
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Fatty Acid ◽  
Potassium Hydroxide ◽  
Seed Oil ◽  
Acid Number ◽  
Moderate Intensity ◽  
Tamarindus Indica ◽  
Tamarind Seed ◽  
Hydrolysis Of

Saponification tamarind seed oil used potassium hydroxide and acidification with hydrochloric acid is produced fatty acid in the form of soft white solid, has melting point 50-55 degrees celcius. The result of this hydrolysis positive test of unsaturation. It has an acid number of 115.36, saponification number of 114.80, and iodine number of 53.34. The success of hydrolysis of oil into fatty acid is characterized by identification of IR spectra showing O-H vibration with moderate intensity and widening, C=O vibration of carboxylic acid with strong intensity. Fatty acids of tamarind seed have the potential as antibacterial to test bacteria Staphylococcus aureus and Escherichia coli with diameter respectively 7.31 mm and 7.58 mm. Minyak biji asam jawa yang disaponifikasi menggunakan kalium hidroksida dan pengasaman dengan asam klorida dihasilkan asam lemak berupa padatan lunak berwana putih, memiliki titik lebur 50-55 derajat celcius. hasil hidrolisis ini positif uji ketidakjenuhan, bilangan asam 115,36, bilangan penyabunan 114,80, dan bilangan iod 53,34. Keberhasilan hidrolisis minyak menjadi asam lemak ditandai dari identifikasi spektrum IR yang menunjukkan vibrasi ulur O-H dengan intensitas sedang dan melebar serta vibrasi ulur C=O asam karboksilat dengan intensitas kuat. Asam lemak biji asam jawa berpotensi sebagai antibakteri terhadap bakteri uji Staphylococcus aureus dan Escherichia coli dengan zona hambat masing-masing 7,31 mm dan 7,58 mm.

scholarly journals A study of the alkaline hydrolysis of fractionated reticulocyte ribosomal ribonucleic acid and its relevance to secondary structure

1968 ◽  
Vol 106 (3) ◽  
pp. 733-741 ◽  
Author(s):  
R A Cox ◽  
Hannah J. Gould ◽  
K Kanagalingam
Keyword(s):  
Secondary Structure ◽  
Phosphate Buffer ◽  
Potassium Hydroxide ◽  
Chain Scission ◽  
Average Chain Length ◽  
Guanidinium Chloride ◽  
Stable Species ◽  
Hairpin Loops ◽  
Ribosomal Ribonucleic Acid ◽  
Hydrolysis Of

1. RNA isolated from the sub-units of rabbit reticulocyte ribosomes was hydrolysed by 0·4n-potassium hydroxide at 20°. The probability of main-chain scission was calculated from the number-average chain length, which was obtained from S25,w in 0·01m-phosphate buffer. 2. The fraction, f, of the original secondary structure that the fragments re-formed at neutral pH in 4m-guanidinium chloride, as well as in 0·01m- and 0·1m-phosphate buffer, was derived from changes in extinction over the range 220–310mμ on thermal denaturation. 3. The secondary structure of RNA is regarded as an assembly of hairpin loops each of 2N+b residues on average, where N is the number of base-paired residues and b is the number of unpaired residues. 4. If chain scission takes place at random then 2N+b=logf/log(1–p). 5. For RNA from the smaller sub-unit 2N+b was estimated as 25±5 residues, compared with 30±5 residues for the less stable species and 35±5 residues for the more stable species of hairpin loop of RNA from the larger sub-unit.

scholarly journals Kinetics of the hydrolysis of N-benzoyl-l-serine methyl ester catalysed by bromelain and by papain. Analysis of modifier mechanisms by lattice nomography, computational methods of parameter evaluation for substrate-activated catalyses and consequences of postulated non-productive binding in bromelain- and papain-catalysed hydrolyses

1974 ◽  
Vol 141 (2) ◽  
pp. 365-381 ◽  
Author(s):  
Christopher W. Wharton ◽  
Athel Cornish-Bowden ◽  
Keith Brocklehurst ◽  
Eric M. Crook
Keyword(s):  
Methyl Ester ◽  
Dissociation Constant ◽  
Computational Methods ◽  
Rate Constant ◽  
Guanidine Hydrochloride ◽  
Ester Hydrolysis ◽  
Binary Complex ◽  
Substrate Activation ◽  
Hydrolysis Of ◽  
Ester Substrate

1. N-Benzoyl-l-serine methyl ester was synthesized and evaluated as a substrate for bromelain (EC 3.4.22.4) and for papain (EC 3.4.22.2). 2. For the bromelain-catalysed hydrolysis at pH7.0, plots of [S0]/vi (initial substrate concn./initial velocity) versus [S0] are markedly curved, concave downwards. 3. Analysis by lattice nomography of a modifier kinetic mechanism in which the modifier is substrate reveals that concave-down [S0]/vi versus [S0] plots can arise when the ratio of the rate constants that characterize the breakdown of the binary (ES) and ternary (SES) complexes is either less than or greater than 1. In the latter case, there are severe restrictions on the values that may be taken by the ratio of the dissociation constants of the productive and non-productive binary complexes. 4. Concave-down [S0]/vi versus [S0] plots cannot arise from compulsory substrate activation. 5. Computational methods, based on function minimization, for determination of the apparent parameters that characterize a non-compulsory substrate-activated catalysis are described. 6. In an attempt to interpret the catalysis by bromelain of the hydrolysis of N-benzoyl-l-serine methyl ester in terms of substrate activation, the general substrate-activation model was simplified to one in which only one binary ES complex (that which gives rise directly to products) can form. 7. In terms of this model, the bromelain-catalysed hydrolysis of N-benzoyl-l-serine methyl ester at pH7.0, I=0.1 and 25°C is characterized by Km1 (the dissociation constant of ES)=1.22±0.73mm, k (the rate constant for the breakdown of ES to E+products, P)=1.57×10-2±0.32×10-2s-1, Ka2 (the dissociation constant that characterizes the breakdown of SES to ES and S)=0.38±0.06m, and k′ (the rate constant for the breakdown of SES to E+P+S)=0.45±0.04s-1. 8. These parameters are compared with those in the literature that characterize the bromelain-catalysed hydrolysis of α-N-benzoyl-l-arginine ethyl ester and of α-N-benzoyl-l-arginine amide; Km1 and k for the serine ester hydrolysis are somewhat similar to Km and kcat. for the arginine amide hydrolysis and Kas and k′ for the serine ester hydrolysis are somewhat similar to Km and kcat. for the arginine ester hydrolysis. 9. A previous interpretation of the inter-relationships of the values of kcat. and Km for the bromelain-catalysed hydrolysis of the arginine ester and amide substrates is discussed critically and an alternative interpretation involving substantial non-productive binding of the arginine amide substrate to bromelain is suggested. 10. The parameters for the bromelain-catalysed hydrolysis of the serine ester substrate are tentatively interpreted in terms of non-productive binding in the binary complex and a decrease of this type of binding by ternary complex-formation. 11. The Michaelis parameters for the papain-catalysed hydrolysis of the serine ester substrate (Km=52±4mm, kcat.=2.80±0.1s-1 at pH7.0, I=0.1, 25.0°C) are similar to those for the papain-catalysed hydrolysis of methyl hippurate. 12. Urea and guanidine hydrochloride at concentrations of 1m have only small effects on the kinetic parameters for the hydrolysis of the serine ester substrate catalysed by bromelain and by papain.

Spectrophotometric Determination of Carbaryl in Grains

1982 ◽  
Vol 65 (1) ◽  
pp. 32-34
Author(s):  
Kalapanda M Appaiah ◽  
Rasamsetti Ramakrishna ◽  
Kadari R Subbarao ◽  
Omprakash Kapur
Keyword(s):  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Potassium Hydroxide ◽  
Oxidizing Agent ◽  
Spectrophotometric Measurement ◽  
The Relationship ◽  
Hydrolysis Of

Abstract A method has been developed for determining carbaryl (1-naphthyl N-methyl carbamate) in grains, based on hydrolysis of carbaryl with methanolic potassium hydroxide to 1-naphthol, reaction with 4-aminophenazone in the presence of alkaline oxidizing agent, and spectrophotometric measurement at the absorption maximum at 475 nm. The relationship between absorbance and concentration is linear in the range of 0.5-20 μg/mL. The method can be applied to levels as low as 0.3 ppm carbaryl in grains.

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