THEORY OF THE EXPERIMENT In this experiment change in the volume of reagents by diluting with water is used as change in the concentration and reciprocal of the time taken for the appearance of blue black colour as the reaction rate. Equation of reaction H2O2 (aq) + 2H+ (aq) +2I- (aq) I2 + 2H2O Hypothesis Hypothesis 1: Decrease in concentration of hydrogen peroxide (H2O2) decreases the rate of reaction (that is, increases the time for reaction to come to completion). In the reaction between potassium iodide (KI), hydrogen peroxide, Sodium thiosulfate (Na2S2O4) under acidic condition. Hypothesis 2: Decrease in the concentration of potassium iodide decreases the rate of reaction (that is increases the time for the reaction to come to completion). In the reaction between potassium iodide (KI), hydrogen peroxide, sodium thiosulfate (Na2S2O3) under acidic condition.
Because it is a tertiary benzylic halide, the reaction is considered an SN1 type. To test the purity, the class then uses a TLC. When one places,” a spot of the substance on the absorbent surface of the TLC plate, the solvent (or solvents) run up through the absorbent,” (Zubrick223). The initial mass of the reactant, triphenylmethyl chloride was 2.006 grams. The experiment yield is 1.589g, which is a 80.3% yield.
If carbocations rearrange during the intermediate phase, the product obtained will be a partial racemic mixture, where the maximum amount of product reflects the most stable carbocation intermediate thru rearrangement. Due to the relative stability of the carbocation, only tertiary alkyl halides can perform SN1 reactions, as shown below. Primary, secondary, and tertiary alcohols can react through substitution but only with hydrobromic acid (HBr), hydrochloric acid (HCl) and hydroiodic acid (HI) because they are good nucleophiles (electron rich atoms). Based on the experiment’s chemical equation: 2-methylcyclohexanol 1-bromo-1-methylcyclohexanol 1-bromo-2-methylcyclohexanol (3o alkyl halide) (2o alkyl halide) The goal of the experiment was to alter a secondary alcohol to isomeric alkyl halides through SN1 dehydration synthesis with hydrobromic acid. Based on the chemical equation, products obtained were 1-bromo-1-methylcyclohexanol (thru 1,2-hydride shift rearrangement) and 1-bromo-2-methylcyclohexanol (no rearrangement).
Bromination is a type of electrophilic aromatic substitution reaction where one hydrogen atom of benzene or benzene derivative is replaced by bromine due to an electrophilic attack on the benzene ring. The purpose of this experiment is to undergo bromination reaction of acetanilide and aniline to form 4-bromoacetanilide and 2,4,6-tribromoaniline respectively. Since -NHCOCH3 of acetanilide and -NH2 of aniline are electron donating groups, they are ortho/para directors due to resonance stabilized structure. Even though the electron donating groups activate the benzene ring, their reactivities are different and result in the formation of different products during bromination. In acetanilide, the lone pair of the nitrogen is delocalized into the
In addition, phenolphthalein was added as an indicator. The aliquots were titrated against sodium hydroxide (NaOH) solution until end point was reached, after which volume of NaOH consumed was recorded. The value of the rate constant, k, obtained was 0.0002 s-1. The experiment was then repeated with 40/60 V/V isopropanol/water mixture and a larger value of k = 0.0007 s-1 was obtained. We concluded that the rate of hydrolysis of (CH3)3CCl is directly proportional to water content in the solvent mixture.
ABSTRACT To catalyze a reaction, an enzyme will grab on (bind) to one or more reactant molecules. In this experiment we examined how increasing the volume of the extract added to the reaction would affect the rate of the reaction. The enzyme used was horseradish peroxidase which helps catalyze hydrogen peroxide. Using different pH levels, the absorbance rate of the reaction was measured to see at which condition the enzyme worked best. The rates of absorption were calculated using a spectrophotometer in 20 second intervals up to 120 seconds.
In this lab, 3-chloro-3,7-dimethyloctane, obtained during a pervious lab, was used to understand the E2 dehydrohalogenation reaction of an alkyl halide. This reaction is possible because 3-chloro-3,7-dimethyloctane contains a carbon-halogen bond, and the chlorine attached to the molecule is a good leaving group. In the dehydrohalogenation of 3-chloro-3,7-dimethyloctane, 1.320g of the starting compound was obtained. This was then added to a mixture of boiling 6mL ethanol and1mL potassium hydroxide. This solution was then heated for 15 minutes until a precipitant formed.
The N‟-2- (bromophenyl)-N,N-dimethylurea 16 underwent lithiation on the nitrogen to form a monolithio intermediate using MeLi, followed by bromine-lithium exchange using t-BuLi to give the dilithio species 17. 14 The intermediate 17 was then exposed to carbon monoxide to give 18, which after cyclization forms the intermediate 19, followed by loss of LiNMe2 to give 20, and finally after work up with dilute acid yielded the isatin product 1. 1 13 14 15 6 N O O 1) MeLi, 0 C CO Br N H O NMe2 2) t-BuLi, 0 C Li N O NMe2 Li C N Li O Li O NMe2 N O NMe2 O Li Li -LiNMe2 N H O O Li H3O + X X X X X X A rather versatile and novel two step synthesis of isatins was presented by Mironov in 2001 and allowed for the preparation of isatins containing electron withdrawing groups such as - CF3, -NO2, and -Cl. The method is based on the reaction between aromatic isocyanides and tertiary amines,15 where in the first step, 2-triethylammonio-3-arylaminoindolates 23 were obtained from the corresponding aromatic formamides 21 without isolation of the intermediate isocyanides 22. 16 Heating the 2-triethylammonio-3-arylaminoindolates 23 in excess thionyl chloride followed by hydrolysis led to the target
The goal of this lab was to prepare methyl m-nitrobenzoate using electrophilic aromatic substitution using nitration. The reaction used methyl benzoate with the acid catalyst as sulfuric acid. The mechanism for the nitration using methyl benzoate is presented in Figure 1. Figure 1: Benzene can only undergo substitution reactions that are called electrophilic aromatic substitution reactions. Given that benzene rings are used commonly in the production of many organic compounds, the capability to make substitutions to benzene is critical.
Introduction:- In organic chemistry the substitution reactions is the most important reactions, especially Nucleophilic aromatic substitution reactions where nucleophile attacks positive charge or partially positive charge As it does so, it replaces a weaker nucleophile which then becomes a leaving group. The remaining positive or partially positive atom becomes an electrophile. The general form of the reaction is: Nuc: + R-LG → R-Nuc + LG: The electron pair (:) from the nucleophile (Nuc :) attacks the substrate (R-LG) forming a new covalent bond Nuc-R-LG. The prior state of charge is restored when the leaving group (LG) departs with an electron pair. The principal product in this case is R-Nuc.