Organic Chemistry Laboratory

The objective of this experiment was to produce triphenylmethyl methyl ether (TPMME) via an S n 1 substitution reaction. The " reflux " method was applied to run the reaction. Methanol was mixed with triphenylmethyl chloride (TPMCl) and then added to a round-bottom flask to be heated and boiled for fifteen minutes. During the fifteen minutes of boiling, the vapors travelled through a simple distillation apparatus, leaving TPMME in the flask to be crystallized. The TPMME was recrystallized using vacuum filtration and tested for purity using a TLC test. The theoretical yield of the TPMME (2.000g) was used to calculate the % yield (50.45%) based on the mass of the recovered TPMME (1.009g). The results of the TLC tests between the product, starting material and a sample of the two combined, concluded that the TPMME was pure. This was determined because the R f value of the product (0.568) was very similar to the R f value of the pure TPMME (0.523) that was separated from the combined sample. Even though the % yield was on the lower side, the sample produced showed to be very pure.

Abstract
Bixin (1) was extracted from Bixa Orellana (annatto) seeds3 and was isolated via column chromatography. Fractions were tested for the presence of (1) and characterized by thin-layer chromatography (TLC) to evaluate the purity of (1) in the experimental extract. The final developed TLC plate resulted in an Rf value of 0.22 for the experimental extract, which is 54.1% of the bixin standard’s Rf value of 0.48. The percent recovery was 19.04%.

The main objective of this experiment was to perform a microscale preparation of benzoic acid via the Grignard reaction. Once the benzoic acid was prepared, it was recrystallized and the purity of the product was assessed by measuring the melting point. Lastly, the % yield was measured to determine how much product was created. To a reaction tube containing 52mg of magnesium, 0.5mL of dry, anhydrous ether was added along with 1mL of bromobenzene through a syringe. A reaction occurred and the phenyl-magnesium bromide (product) was poured over dry ice (CO 2). The ice melted and the ether evaporated, leaving a glassy substance behind (magnesium bromide salt of benzoic acid). The addition of hydrochloric acid dissolved the remaining metal and pure benzoic acid was crystallized via vacuum filtration and purity was assessed by measuring the melting point. When the experiment was completed, the % yield was measured (5.29%), showing some inefficiencies. The melting point was then measured and since the product MP range(87-89ºC) was so much lower than the literature MP (122ºC), the product was not pure.

Despite the fact that Chemistry is the gatekeeper and backbone of other science subjects, the general performance in Chemistry among secondary school students countrywide remains poor. Research evidence shows that poor performance in Chemistry not only results from intrinsic conceptual difficulties in the subject but also springs from poor Chemistry Laboratory work. However, Chemistry educationists seem to be in disagreement with respect to the relationship between Chemistry Laboratory work and students’ academic performance in Chemistry. This study, therefore, sought to find out the relationship between Chemistry Laboratory work and students’ academic performance in Chemistry. The study was guided by John Dewey’s Constructivist Learning theory. The study was conducted in Kilifi North Constituency. The research design was correlation, simple random sampling was used to select one girl school, six mixed schools, and Purposive sampling was used to select one boys’ school. Stratified random sampling and simple random sampling were used to select 80 students. Data was collected by use of Student Questionnaire (SQ) and through analysis of documents and mark sheet form. Statistical package for social sciences (SPSS) was used to facilitate data analysis. Descriptive statistics and inferential statistics were used. The level of significant used in the study was 0.05. The findings revealed, 27.5% of schools utilize the expected 11-13 lessons per term, 33.75% utilizes 7-10 lessons and 38.75% utilizes 3-6 lessons. The findings emerging from this study also revealed that there was a significant positive relationship between; the use of chemistry laboratory and student’s academic performance in chemistry. In conclusion, students whose teachers always take them to the laboratory during practical lessons performed better in practical examinations.

In this experiment, un unknown solid was identified by using a Thomas Hoover Apparatus to determine the mixture melting point. The melting point (mp) range for Unknown #3 was 109.5C-112.7C. The mp range was compared to the known mp for a set of solids provided in a data table. The closest matches to Unknown #3 (acetanilide, 113-115C; fluorene, 114-116C) were mixed with the unknown substance to find mixture mp. The results concluded that the unknown was acetanilide because the melting point measured was within the literature mp range.

The purpose of this experiment was to identify two unknowns by separating a mixture using fractional distillation. The process of fractional distillation was used to separate two components of a mixture based on the differences in boiling points of the two. The mixture was heated and the unknowns separated, lower boiling point first, through the process of evaporation and condensation into marked test tubes. Once the unknowns were separated, a refractive index was measured using a refractometer to further confirm the identity of the two compounds. The unknown mixture used in this experiment was unknown #6, which was a mixture of methanol (lower BP) and 2-methyl-1-propanol (higher BP). Methanol has a boiling point of 64.7C and a refractive index of 1.3292, while unknown A had an average boiling point of 70.1C and a refractive index of 1.3341. Unknown A's BP and RI came the closest to methanol's BP and RI, confirming that it was methanol. 2-methyl-1-propanol has a boiling point of 108C and a refractive index of 1.3960, while unknown B had an average boiling point of 106.1C. These similar values confirmed the identity of unknown B as 2-methyl-1-propanol. Boiling points and refractive indices were used to match the unknowns with a known compound.

The chemistry of salt is of great importance due to its immense potential from the daily life use to the synthetic chemistry like as workup material, as reagents, as phase transfer catalyst, as acid, as base, as catalyst, as agents for asymmetric synthesis, for some specific reaction transformation, to increase yield, decrease reaction time, ecofriendly synthesis, handling easiness and many more. This review summarizes the overall basic background of salts like how it is formed, nature of salt, generalized application of salts in daily life to synthetic chemistry, its application on other diverse fields, and list of individual categories of major commercially available salts with some structure. Besides having a lot of information on the internet about salts, this review tries to focus on a generalized overview that could be helpful for all to understand salt chemistry.

In the Extraction experiment, liquid-liquid extraction was used to separate and purify naphthalene and benzoic acid from a mixture of the two through a separatory funnel. This process works by dissolving the naphthalene/benzoic acid mixture into two different solvents, one aqueous and one organic (ether) solution. Naphthalene was combined with the organic solvent, tert-butyl methyl ether (TBME) and the benzoic acid was combined with the aqueous solvent, sodium hydroxide (NaOH). These two solutions did not mix due to differences in polarity, making it possible to separate the two through the funnel. Once the extraction was finished, the recrystallization process was used to remove the pure compounds from their respective solvents and the percent recoveries of naphthalene (49.0%) and benzoic acid (71.4%) were calculated. To confirm the purity of the recrystallized naphthalene and benzoic acid, a thin layer chromatography (TLC) experiment was performed comparing the two pure compounds to the original mixture of the two. The R f values were then calculated for the pure naphthalene (0.224), benzoic acid (0.830), and the two parts of the original mixture (naphthalene: 0.269, benzoic acid: 0.810). The similarities of the R f values concluded that the " pure " naphthalene and benzoic acid were, indeed, pure. Melting points would have further-supported the purity of the isolated substances, but they were not measured in this experiment due to time constraints.

In the Thin Layer Chromatography (TLC) experiment, food dyes, analgestic tablets, and three different solvents were used to identify and determine polarity of known and unknown compounds. In the food dye experiment, the developing solvent used was composed of 1-butanol, ethyl acetate, ethanol, water and glacial acetic acid. In the two analgestic experiments, the two solvents used were ethyl acetate and acetic acid, and ethyl acetate and hexanes. Once the TLC plates developed, they were viewed by both the naked eye, and under ultra violet light. R f values were calculated using the equation, R f =distance from baseline traveled by solute/distance from baseline traveled by solvent. The higher the Rf value, the less polar the compound was. Rf values did not exceed 1.0.

Preparation of 0.1 M Na2CO3 solution in 250 ml D.W
part per million (PPm  )
Buffer solution
Preparation of 1%  w/v Na2CO3 solution
Concentration units
g(sample)=M.wt(sample)*Molarity*Volume
M1×V1=M2×V2
mass percent solution=(gram(solute))/(100 grams(soluion))%
D=mass/volume≫≫mass=Denstiy ×Volume

In the Crystallization experiment, glass wool, a Hirsch funnel, and a hot plate were key pieces of equipment used to purify a naphthalene compound through the process of recrystallization. Impure naphthalene crystals were heated and dissolved in a methanol solute, then cooled and filtered through the Hirsch funnel using vacuum filtration. The pure recrystallized naphthalene crystals were weighed to find the percent error. The purity of the recrystallized naphthalene was proven by using a Thomas Hoover Apparatus to find the observed melting point (79.5C) that could then be compared to the, nearly identical, literature melting point (80.26C). Of the initial 1.014g of impure naphthalene collected, 0.764g of pure naphthalene were recovered after the recrystallization, demonstrating a 75.3% recovery. Purpose/Theory

The intention of this lab was to learn how to isolate caffeine from tea leaves using the method of extraction. Six teabags were steeped for 2 minutes before sodium carbonate was added. In a separatory funnel, the cooled tea/sodium carbonate mixture was added, followed by 3 rounds of 20mL of ethyl acetate. The mixture separated into an aqueous layer (tea and water) and an organic layer (caffeine and ethyl acetate). The aqueous layer was discarded and the organic layer was drained into a clean flask. The caffeine was recrystallized using a RotoVap. Once isolated and recrystallized, the purity of the caffeine was to be determined via melting points and thin layer chromatography. The end-goal of the experiment was to determine the percent recovery of caffeine extracted from the tea bag with a 2% mass assumption and the % recovery by mass. The extracted caffeine was compared to pure caffeine in a TLC test and the Rf values were compared to assess the purity of the extracted sample. The calculated Rf value for the pure caffeine was 0.625 and the Rf value for the extracted caffeine was 0.596. The similar Rf values concluded that the extracted caffeine was mostly pure. The % recovery based on the 2% mass assumption was 59.6%. The % recovered based on the mass of the teabags as a whole was 1.17%, which means 59.6% of the 2% mass of caffeine in the teabags was recovered. Melting points were not measured due to time constraints.

The objectives of this experiment were to study the optical rotation of enantiomers using polarimetry and to understand how concentration, cell length, observed rotation (α obs), and specific rotation [α] are related. Measurements of specific rotation and enantiomeric excess were calculated and chirality centers were identified. Another objective was to learn and identify the relationship between stereoisomers. The enantiomers used in this experiment were: (R)-(-)-Carvone, (S)-(+)-Carvone, (S)-(-)-Limonene, (R)-(+)-Limonene, unknown substance A, and sucrose solution B. The unknown was identified ((S)-(-)-Limonene) by comparing the observed rotations. Once all rotation values were calculated, % error was found for R-(-)-carvone (4.26%) and R-(+)-limonene (28.27%) in part A, % ee was found for (S)-(+)-Carvone (69.5%) and (S)-(-)-Limonene (56.4%) in part B, % difference for [α] of unknown A/(S)-(-)-Limonene and known [α] (4.26%) was found in part C, and the concentration of the sucrose solution (0.221 g/cm 3) was calculated.

Se presentan resultados de la investigación sobre el estado físico que guardan los laboratorios de ciencia de 479 escuelas secundarias generales del Distrito Federal, México.  Se expone el estado que guarda el conocimiento sobre el tema, a partir del análisis de bibliografía especializada, publicada a nivel mundial entre 1970 y 1994.  A la luz del estudio, fue diseñado el método específico de recolección,  procesamiento y análisis de información de campo.  Se centró en las condiciones del equipo y de las instalaciones (eléctrica, hidráulica y de gas) que en 1994 tenían los laboratorios de las escuelas secundarias generales, así como las de los locales (espacios físicos) que los albergan.  Las condiciones infraestructurales, se presentan de manera interrelacionadas con dos categorías:  i)la asignatura (Biología, Física y Química) que atiende el laboratorio; ii)ubicación geográfico-política de las escuelas en que están los laboratorios (es decir, ubicación de las escuelas, en las delegaciones políticas que conforman al Distrito Federal).  El documento incluye también una propuesta de líneas de investigación que quedan abiertas para ser abordadas en el futuro inmediato.

Anthracyclines are effective drugs in the treatment of various cancers, but their use comes with severe side effects. The archetypal anthracycline drug, doxorubicin, displays two molecular modes of action: DNA double-strand break formation (through topoisomerase IIα poisoning) and chromatin damage (via eviction of histones). These biological activities can be modulated and toxic side effects can be reduced by separating these two modes of action through alteration of the aminoglycoside moiety of doxorubicin. We herein report on the design, synthesis, and evaluation of a coherent set of configurational doxorubicin analogues featuring all possible stereoisomers of the 1,2-amino-alcohol characteristic for the doxorubicin 3-amino-2,3-dideoxyfucoside, each in nonsubstituted and N,N-dimethylated forms. The set of doxorubicin analogues was synthesized using appropriately protected 2,3,6-dideoxy-3-amino glycosyl donors, equipped with an alkynylbenzoate anomeric leaving group, and the doxorubicin aglycon acceptor. The majority of these glycosylations proceeded in a highly stereoselective manner to provide the desired axial α-linkage. We show that both stereochemistry of the 3-amine carbon and N-substitution state are critical for anthracycline cytotoxicity and generally improve cellular uptake. N,N-Dimethylepirubicin is identified as the most potent anthracycline that does not induce DNA damage while remaining cytotoxic.

The chemistry of salt is of great importance due to its immense potential from the daily life use to the synthetic chemistry like as workup material, as reagents, as phase transfer catalyst, as acid, as base, as catalyst, as agents for asymmetric synthesis, for some specific reaction transformation, to increase yield, decrease reaction time, ecofriendly synthesis, handling easiness and many more. This review summarizes the overall basic background of salts like how it is formed, nature of salt, generalized application of salts in daily life to synthetic chemistry, its application on other diverse fields, and list of individual categories of major commercially available salts with some structure. Besides having a lot of information on the internet about salts, this review tries to focus on a generalized overview that could be helpful for all to understand salt chemistry.

A set of model nucleophiles of gradually changing nucleophilicity is used to probe the glycosylation reaction mechanism. Glycosylations of ethanol-based acceptors, bearing varying amounts of fluorine atoms, report on the dependency of the stereochemistry in condensation reactions on the nucleophilicity of the acceptor. Three different glycosylation systems were scrutinized, that differ in the reaction mechanism, that – putatively – prevails during the coupling reaction. It is revealed that the stereoselectivity in glycosylations of benzylidene protected glucose donors are very susceptible to acceptor nucleophilicity whereas condensations of benzylidene mannose and mannuronic acid donors represent more robust glycosylation systems in terms of diastereoselectivity. The change in stereoselectivity with decreasing acceptor nucleophilicity is related to a change in reaction mechanism shifting from the SN2 side to the SN1 side of the reactivity spectrum. Carbohydrate acceptors are examined and the reactivity–selectivity profile of these nucleophiles mirrored those of the model acceptors studied. The set of model ethanol acceptors thus provides a simple and effective “toolbox” to investigate glycosylation reaction mechanisms and report on the robustness of glycosylation protocols.

The mechanism of the Lewis base F– catalyzed 1,3-dipolar cycloaddition between CO2 and nitrilimines is interrogated using DFT calculations. F– activates the nitrilimine, not CO2 as proposed in the literature, and imparts a significant rate enhancement for the cycloaddition. The origin of this catalysis is in the strength of the primary orbital interactions between the reactants. The Lewis base activated nitrilimine–F– has high-lying filled FMOs. The smaller FMO-LUMO gap promotes a rapid nucleophilic attack and overall cycloaddition with CO2.

The existence of large aromatic monocycles has been proved impossible based on interaction of three-electron bonds through the cycle at distances between the bonds (through the cycle) greater than 3.5 Å due to the lack of energy interaction (the length of chemical bonds is in the range of distances 0.74 Å – 3.5 Å). The chemical bond (two-electron and three-electron) is considered on the assumption that the electrons in a chemical bond can be regarded as being in an entangled quantum state, that is, the chemical bond is seen as a new "indivisible" particle. There has been provided an algorithm for calculating the two-electron chemical bond "on the tip of the pen". An attempt was made to explain the mechanism of interaction of particles in an entangled quantum state on the basis of a new model of the interfering Universe. The interaction of two three-electron bonds in a molecule of benzene at a distance of 2.42 Å (on opposite sides) can be explained if we consider these two three-electron bonds as two particles (two fermions) in an entangled quantum state [1, p. 4-11]. That is, these two fermions are in an entangled quantum state. Quantum entanglement is a quantum mechanical phenomenon, in which the quantum states of two or more fermions or bosons prove to be interconnected [2-6]. And surprisingly, this interconnection remains at virtually any distance between the particles (when there are no other known interactions). It should be realized that the entangled quantum system is in fact an "indivisible" object, a new particle with certain properties (and the particles of which it is composed should meet certain criteria). And most importantly, when measuring the spin (or other property) of the first particle we will automatically unambiguously know the spin (property) of the second particle (let's say we get a positive spin of the first particle, then the spin of the second particle will always be negative, and vice versa). Two particles in an entangled state prove to be bound by an "invisible thread", that is, in fact, they form a new "indivisible" object, a new particle. And this is an experimental fact.

Using the concept of three-electron bond one can represent the actual electron structure of benzene, explain specificity of the aromatic bond and calculate the delocalization energy. It was shown, that functional relation y = a + b/x + c/x^2 fully describes dependence of energy and multiplicity of chemical bond on bond distance. In this article carbon-to-carbon bonds are reviewed. Using these dependences it is possible to calculate chemical bound energy by different bond distance or different multiplicity of chemical bond, that makes possible to calculate delocalization energy of benzene molecule.

Aim of this research is to evaluate the impact of argumentation in the chemistry laboratory on conceptual comprehension of students. This research follows a triangulation design, categorized under mixed-method design variations, which include both qualitative and quantitative research designs. The research is conducted with 91 first grade university students studying in two different classes of the Department of Science Education, Kazım Karabekir Education Faculty at the Ataturk University, located in eastern Turkey. One class was randomly designated as the experimental group, with another as the control group. Research data was collected via a General Chemistry Laboratory Concept Test (GCLCT) containing 33 items, a test containing ten open-ended items, a semi-structured interview form, and a written feedback form, all designed by the researchers. Data from the GCLCT were analyzed through predictive statistics method, while data from the open-ended questions, semi-structured interview and written feedback form were analyzed through the descriptive analysis method. It is concluded from this research, that there is statistically significant difference between the GCLC post-test averages of the experimental and control groups. It was found that when compared to the control group, the proportion of experimental group students who answered the GCLC post-test items correctly is higher. In addition to this, the proportion of students who demonstrated misconceptions were higher in the control group students compared to the experimental group. It is concluded by this research, that argumentation provides more effective results in terms of comprehension of fundamental chemistry concepts, when compared to a traditional approach.

The aim of this research is to analyze the effect of Argumentation on prospective
science teachers' scientific process skills and their understanding of the nature of
scientific knowledge in the chemistry laboratory. In this study, non-equivalent pre-test
post-test control group approach, which is one of the quasi-experimental methods, is
used. The study group contains 91 college freshmen students studying in the
Department of Science Education of the Kazim Karabekir Education Faculty, Ataturk
University, which is located in the Eastern Anatolian Region of Turkey. Data of the
study is collected through scientific process skill test (SPST) and the nature of scientific
knowledge test (NSKT). Data from SPST and NSKT are analyzed through inferential
statistics method. A statistically significant difference is found between experimental
and control groups' SPS post-test mean scores (t(89)= 4.943; p= .000). A statistically
significant difference is found between experimental and control groups' NSK post-test
mean scores (t(89)= .819; p= .05). It is shown in this study that the argumentation
contributes to the scientific process skills of the students, but does not have a
significant influence on their understanding of the nature of scientific knowledge.

Der α-Effekt ist ein „Reaktivitats-Booster“, der dem weniger basischen Peroxid (HOO−) den Vorteil gegenuber Hydroxid (HO−) im Grand Prix der SN2-Reaktivitat verschafft! In ihrem Forschungsartikel (DOI: 10.1002/ange.202106053) stellen Trevor A. Hamlin et al. zwei Kriterien auf, die α-Nucleophile erfullen mussen, um einen α-Effekt zu zeigen: (i) ein kleiner HOMO-Lappen am nukleophilen Zentrum, um die destabilisierende Pauli-Abstosung mit dem Substrat zu verringern; und (ii) ein hochenergetisches HOMO, um den Verlust der gunstigen Orbitaluberlappung mit dem Substrat zu uberwinden.

Entre las técnicas de separación de mezclas existe la de cromatografía la cual está dividida en varios métodos, como la cromatografía sólido-líquido, líquido-líquido y gas-líquido, cada uno puede separar diferentes tipos de sustancias, pero el que se va a utilizar  en este laboratorio es cromatografía sólido-líquido que contiene varios procesos: cromatografía de columna, cromatografía de papel y cromatografía de capa fina; esta última sirve para separar azúcares simples, lípidos, aminoácidos y para separar los pigmentos de las hojas, como la clorofila A y B que son los encargados de dar el color verde de las hojas.