An efficient and inexpensive device for undergraduate chemistry classes aiming teaching the photolytic synthesis concepts

Quim. Nova 2014, 37(1), 164-167,  2014

Um reator fotoquímico barato e eficiente para experimentos de química

Ramon Kenned Sousa Almeida^I; Cláudia Martelli^I; Gilson Herbert Magalhães Dias^I; Julio Cesar Araujo da Silva^{II, *}

An efficient and inexpensive device for undergraduate chemistry classes aiming teaching the photolytic synthesis concepts. This device presents simplicity, low costs, class-compatible reaction times and good yields. Ramon Kenned Sousa Almeidaa , Cláudia Martellia , Gilson Herbert Magalhães Diasa e Julio Cesar Araujo da Silvab,* a Instituto de Química, Universidade Estadual de Campinas, 13083-970 Campinas – SP, Brasil b Instituto Federal de Ciência e Tecnologia de Santa Catarina, Estrada do Senadinho, s/no , Centro, 88625-000 Urupema – SC, Brasil A CHEAP AND EFFICIENT PHOTOCHEMICAL REACTOR FOR CHEMICAL EXPERIMENTS. In this work, we present an efficient and inexpensive device for undergraduate chemistry classes aimed at teaching and learning the photolytic synthesis concepts. A photochemical reactor was tested for the synthesis of the organometallic compound enneacarbonyldiiron from iron pentacarbonyl in acetic acid, and its formation evidenced by FTIR analysis. Although similar devices have been described in other studies, none of these offered the simplicity, low cost, class-compatible reaction times and good yields afforded by the procedure reported herein. Keywords: photochemistry; reactor; enneacarbonyldiiron.                         Instituto de Química, Universidade Estadual de Campinas  

1. 1. 

  Instituto Federal de Ciência e Tecnologia de Santa Catarina, Estrada do Senadinho

Campus Palhoça-Bilingue. Atualizado por Rafael Batista. O Instituto Federal de Educação, Ciência e Tecnologia de Santa Catarina ...     Aberto o concurso do Instituto Federal de Educação, Ciência e Tecnologia de Santa Catarina (IFSC). A seleção visa prover um total de 145 vagas.   Instituto Federal de Educação, Ciência e Tecnologia - Campus Rio do Sul - Cantagalo

Synthesis of 2-dimethylaminomethyl-cyclohexanone hydrochloride

Synthesis of 2-dimethylaminomethyl-cyclohexanone hydrochloride

http://orgspectroscopyint.blogspot.in/2014/09/synthesis-of-2-dimethylaminomethyl.html




++

EtOH, HCl

Synthesis of 2-dimethylaminomethyl-cyclohexanone hydrochloride

Reaction type:	reaction of the carbonyl group in aldehydes, Mannich reaction
Substance classes:	ketone, aldehyde, amine
Techniques:	heating under reflux, stirring with magnetic stir bar, evaporating with rotary evaporator, filtering, recrystallizing, heating with oil bath
Degree of difficulty:	Easy

Equipment

	round bottom flask 25 mL			reflux condenser
	suction filter			suction flask
	heatable magnetic stirrer with magnetic stir bar			rotary evaporator
	exsiccator with drying agent			oil bath

Instruction (batch scale 100 mmol) 

Equipment 

100 mL round bottom flask, reflux condenser, Buechner funnel (Ø 5.5 cm), suction flask, 

heatable magnetic stirrer, magnetic stir bar, rotary evaporator, desiccator, oil bath 

Substances 

cyclohexanone (bp 156 °C) 9.82 g (10.3 mL, 100 mmol) 

paraformaldehyde (mp 120-170 °C) 3.60 g (120 mmol) 

dimethylammonium chloride 8.16 g (100 mmol) 

hydrochloric acid (conc.) 0.4 mL 

ethanol (bp 78 °C) 64 mL 

acetone (bp 56 °C) 180 mL 

Reaction 

9.82 g (10.3 mL, 100 mmol) cyclohexanone, 3.60 g (120 mmol) paraformaldehyde, 8.16 g 

(100 mmol) dimethylammonium chloride and 4 mL ethanol are filled in a 100 mL round 

bottom flask with reflux condenser and magnetic stir bar. 0.4 mL conc. hydrochloric acid are 

added and the mixture is heated under stirring for 4 hours under reflux. 

Work up 

The hot solution is filtered in a round-bottom flask and the solvent is evaporated at the rotary 

evaporator. The residue is dissolved in 20 mL ethanol under heating. At room temperature 

70 mL acetone are added to the solution. For complete crystallization the solution is stored 

over night in the freezer compartment. The crystallized crude product is sucked off over a 

Buechner funnel (Ø = 5.5 cm) and dried in the desiccator over silica gel. 

Crude yield: 15.6 g; mp 149-150 °C 

For further purification the crude product is again dissolved in about 40 mL ethanol under 

reflux and at room temperature 110 mL acetone are added. The crystallization is completed in 

the freezer compartment. The product is sucked off and dried in the desiccator. 

Yield: 14.7 g (76.7 mmol, 77%,); mp 156-157 °C 

Comments 

To verify a complete crystallization, the mother liquor is stored in the freezer compartment. 

No product should crystallize any further.

Simple evaluation indices

Atom economy		not defined
Yield		76	%
Target product mass		1.45	g
Sum of input masses		54	g
Mass efficiency		27	mg/g
Mass index		37	g input / g product
E factor		36	g waste / g product

1H-NMR: 2-Dimethylaminomethyl cyclohexanone hydrochloride
500 MHz, CDCl3
delta [ppm]	mult.	atoms	assignment
1.35	m	1 H
1.54	m	1 H
1.73	m	1 H
1.82	m	1 H
2.05	m	1 H
2.37	m	2 H	6-H (ring)
2.41	m	1 H
2.67	d	3 H	N-CH3
2.74	m	1 H
2.77	d	3 H	N-CH3
3.09	m	1 H	N-CH2
3.57	m	1 H	N-CH2
11.88	m	1 H	N-H
7.26			CHCl3

13C-NMR: 2-Dimethylaminomethyl cyclohexanone hydrochloride
125 MHz, CDCl3
delta [ppm]	assignment
24.70	C5
27.70	C3
33.88	C4
41.75	CH3
42.26	CH3
44.99	C6
46.69	C2
56.80	-CH2-N-
209.58	C1 (C=O)
76.5-77.5	CDCl3

IR: 2-Dimethylaminomethyl cyclohexanone hydrochloride
[Film, T%, cm-1]
[cm-1]	assignment
3068, 3020	N-H valence
2932, 2858	C-H valence
1698	C=O valence, ketone

http://kriemhild.uft.uni-bremen.de/nop/en/instructions/pdf/4008_en.pdf

Self-contained chemical synthesis

Scientists in the UK have used reactors made on a 3D printer to complete a three stage organic synthesis. The reagents, catalyst and purification step for the synthesis are completely integrated into the chambers of the sealed reactor. When the reactor is rotated, gravity pulls reactants through the different chambers to complete the synthesis.
read all at
http://www.rsc.org/chemistryworld/2013/06/organic-synthesis-reactor-3d-printer

From the Wings of Butterflies: The Discovery and Synthesis of Alimta

Vol. 33 No. 5
September-October 2011

From the Wings of Butterflies: The Discovery and Synthesis of Alimta

http://www.iupac.org/publications/ci/2011/3305/1_taylor.html

by Edward C. Taylor

The following essay describes in broad terms the history of the discovery of Alimta. It was written as a part of a brochure celebrating the dedication of Princeton’s magnificent new chemistry building, completed by the end of 2010. The building, recognized as perhaps the finest, best-equipped, and designed facility for academic chemistry research in the country, was financed by royalties to Princeton from sales of Alimta by Eli Lilly & Co., to whom Princeton had given an exclusive license. The article was addressed to a general audience; my lecture in Glasgow1 filled in the organic and heterocyclic chemistry involved in the extensive explorations that finally led to the discovery and synthesis of Alimta.

http://www.iupac.org/publications/ci/2011/3305/1_taylor.html





.......

DNA: From Structure to Synthesis

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Vol. 35 No. 2
March-April 2013

DNA: From Structure to Synthesis

by Krishna N. Ganesh
 http://www.iupac.org/publications/ci/2013/3502/2_caruthers.html

The DNA double helix made up of two antiparallel strands complementary to each other through specific base pairing of A with T and G with C codes the key information necessary for synthesis and regulation of all proteins and enzymes required of functioning of a cell from cell division to cell differentiation and cell development. The discovery also gave birth to the fields of molecular and structural biology, which have been key to the genetic revolution that has resulted in the development of vital products, ranging from hormones and enzymes to therapeutic molecules and vaccines. The penultimate achievement stemming from the discovery of DNA’s structure was the unraveling of the entire human genome in 2001 and work continues unabated on the genomes of other organisms. These discoveries have implications for our understanding of diseases at the molecular level and, thereby, the development of cures. Some of the most spectacular applications take advantage of the self-assembling properties of the genetic molecule DNA to make nonbiological novel generic materials.http://www.iupac.org/publications/ci/2013/3502/2_caruthers.html

Novel Aromatic Compounds

Novel Aromatic Compounds

by Shih-Yuan Liu and Michael Haley
The 14th International Symposium on Novel Aromatic Compounds (ISNA-14) was held 24–29 July 2011 in Eugene, Oregon, USA, on the campus of the University of Oregon. Over 250 participants from 21 countries were present, making this gathering the largest ISNA conference on North American soil. The scientific program consisted of the 2011 Nozoe Lecture presented by Peter Bäuerle (University of Ulm, Germany), 11 plenary lectures, 20 invited lectures, 29 contributed lectures, and 160 posters presented in two sessions. This IUPAC-sponsored symposium was organized by Michael M. Haley (University of Oregon) and Benjamin T. King (University of Nevada, Reno, USA).

http://www.iupac.org/publications/ci/2011/3306/cc1_240711.html



,

Hybrid Nanoscale Ligand

A new salen–C₆₀ dyad forms complexes with transition metals, thereby tuning the optical, redox, and catalytic properties
Read more

sp3-Carbon-Based Liquid Crystals

The liquid-crystalline phase of poly(ethylidene acetate) is described and explained by the formation of triple-helix aggregates
Read more

Bond-Length Alternation in Overcrowded Borazines

X-ray crystallography and state-of-the art computations were applied to the question of bond-length alternation in overcrowded borazines
Read more

Fries Rearrangement Mechanism

The Fries rearrangement proceeds through ionic intermediates. The reaction depends on the structure of the substrates and the reaction conditions. 

The scheme depicts the formation of an ortho-acylated phenol from a substituted phenolic ester in the presence of aluminium trihalide catalyst. The photo Fries rearrangement mechanism proceeds through Radical intermediates.




The Fries rearrangement, named for the German chemist Karl Theophil Fries, is a rearrangement reaction of a phenyl ester to a hydroxy aryl ketone by catalysis of Lewis acids.^[1][2][3][4]
It involves migration of an acyl group of phenyl ester to benzene ring. The reaction is ortho and para selective and one of the two products can be favoured by changing reaction conditions, such as temperature and solvent.

Mechanism

Despite many efforts a definitive reaction mechanism for the Fries rearrangement is not available. Evidence for inter- and intramolecular mechanisms have been obtained by so-called cross-experiments with mixed reactants. Reaction progress is not dependent on solvent or substrate. A widely accepted mechanism involves a carbocation intermediate.

In the first reaction step a Lewis acid for instance aluminium chloride AlCl
3 co-ordinates to the carbonyl oxygen atom of the acyl group. This oxygen atom is more electron rich than the phenolic oxygen atom and is the preferred Lewis base. This interaction polarizes the bond between the acyl residue and the phenolic oxygen atom and the aluminium chloride group rearranges to the phenolic oxygen atom. This generates a free acylium carbocation which reacts in a classical electrophilic aromatic substitution with the aromatic ring. The abstracted proton is released as hydrochloric acid where the chlorine is derived from aluminium chloride. The orientation of the substitution reaction is temperature dependent. A low reaction temperature favors para substitution and with high temperatures the ortho product prevails. Formation of the ortho product is also favoured in non-polar solvents; as the solvent polarity increases, the ratio of the para product also increases.^[5]

Scope

Phenols react to esters but do not react to hydroxyarylketones with acylhalogen compounds under Friedel-Crafts acylation reaction conditions and therefore this reaction is of industrial importance for the synthesis of hydroxyarylketones which are important intermediates for several pharmaceutics such as paracetamol and salbutamol. As an alternative to aluminium chloride, other Lewis acids such as boron trifluoride and bismuth triflate or strong protic acids such as hydrogen fluoride and methanesulfonic acid can also be used. In order to avoid the use of these corrosive and environmentally unfriendly catalysts altogether research into alternative heterogeneous catalysts is actively pursued.

Limits

In all instances only esters can be used with stable acyl components that can withstand the harsh conditions of the Fries rearrangement. If the aromatic or the acyl component is heavily substituted then the chemical yield will drop due to steric constraints. Deactivating meta-directing groups on the benzene group will also have an adverse effect as can be expected for a Friedel–Crafts acylation.

Photo-Fries rearrangement

In addition to the ordinary thermal phenyl ester reaction a so-called photochemical Photo-Fries rearrangement exists^[6] that involves a radical reaction mechanism. This reaction is also possible with deactivating substituents on the aromatic group. Because the yields are low this procedure is not used in commercial production. However, photo-Fries rearrangement may occur naturally, for example when a plastic bottle made of polyethylene terephthalate (PET) is exposed to the sun, particular to UV light at a wavelength of about 310 nm, if the plastic has been heated to 40 degrees Celsius or above (as might occur in a car with windows closed on a hot summer day). In this case, photolysis of the ester groups would lead to leaching of phthalate from the plastic.^[7]

Anionic Fries rearrangment

In addition to Lewis acid and photo-catalysed Fries rearrangements, there also exists an anionic Fries rearrangement. In this reaction, the aryl ester undergoes ortho-metallation with a strong base, which then rearranges in a nucleophilic attack mechanism.

1.  Fries, K. ; Finck, G. (1908). "Über Homologe des Cumaranons und ihre Abkömmlinge". Chemische Berichte 41 (3): 4271–4284. doi:10.1002/cber.190804103146.
2.  Fries, K.; Pfaffendorf, W. (1910). "Über ein Kondensationsprodukt des Cumaranons und seine Umwandlung in Oxindirubin". Chemische Berichte 43 (1): 212–219. doi:10.1002/cber.19100430131.
3.  March, J. Advanced Organic Chemistry, 3rd Ed.; John Wiley & Sons: Chichester, 1985; S. 499ff.
4.  Blatt, A. H. Org. React. 1942, 1.
5.  Kürti, László; Czakó, Barbara (2005). Strategic Applications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms. Elsevier Academic Press. p. 181. ISBN 0123694833.
6.  Bellus, D. Advances in Photochemistry; John Wiley & Sons: Chichester, 1971; Vol. 8, 109–159.
7.  Norma Searle, "Environmental effects on polymeric materials," pp. 313–358, in Plastics and the Environment, edited by Anthony Andrade, Wiley, 2003.