Chemistry of lac resin—I

Wadia, M. S.; Khurana, R.; Mhaskar, V.V.; Dev, Sukh

doi:10.1016/s0040-4020(01)82916-1

Cited by 40 publications

(15 citation statements)

References 23 publications

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“…This resinous secretion, called Seed Lac once semi-refined, contains resin, dyes and 6-7% wax. Seed Lac is processed separating the wax, shellac wax, from the principally resinous part, shellac [27,28]. However, small wax impurities can still be found in shellac, principally used in varnishes and coatings.…”

Section: Beeswax From Conservation Treatments and Wax From Natural Immentioning

confidence: 99%

Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks

Beltrán

Salvadó

Butí

et al. 2015

Microchemical Journal

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The presence of coating on manufactures either to protect them from the environment, or to give them specific properties -as well as simply to change their aspect -has shown to be a constant practise throughout history. Their characterization is complex not only because of the inherent variability and diversity of the composition, but also due to the small amount of sample material available. A methodology to study those coatings using microFTIR is proposed. In some cases the use of microSR-FTIR which heavily increases spatial resolution particularly appropriate for the analysis of these heterogeneous samples is also proposed. Data processing tools such as distribution maps of specific infrared bands and curve fitting facilitate the interpretation of the spectra and help identifying heavily overlapped spectra. Through the identification of individual bands, it has been possible to discriminate materials and comprehend the interaction processes during aging. Infrared spectra from reference aged materials of known production dates and which are essential in understanding those processes are given. A set of selected case studies including materials of different chemical nature and various historical periods are presented: identification of guanine on an inner coating of a hope chest; determination of a protein glue coating from a gilded Baroque altarpiece; assessment of a beeswax superficial application during an historical restoration of a late 19 th century canvas painting; identification of impurities of shellac wax in a shellac coating on a wood moulding from a medieval altarpiece; aging and reaction compounds in Pinus resin, drying oil and green copper pigment mixtures used as colour coatings on Baroque and modern desks.

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Section: Beeswax From Conservation Treatments and Wax From Natural Immentioning

confidence: 99%

Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks

Beltrán

Salvadó

Butí

et al. 2015

Microchemical Journal

View full text Add to dashboard Cite

show abstract

“…It is a mixture of resin (70–80%), wax (6–7%) and colourant molecules (4–8%) 8 , obtained by refining sticklac, which is the material collected directly from the plant. After washing the sticklac, most of the water-soluble material (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…; jalaric and laccijalaric acids. The relative amounts of these acids and the manner in which the corresponding esters are formed differ for the “soft” and “hard” resin, with the “soft” resin generally having a lower molecular weight and the “hard” resin constituting the backbone of the material 8,10–15 . Minor compounds are also present among the hydroxyaliphatic acids, such as 6-oxotetradecanoic acid, 16-hydroxyhexadecanoic acid, 6-hydroxyhexadec-9-enoic acid, 9,10-dihydroxytetradecanoic acid and 9,10-dihydroxyhexadecanoic acid 16 .…”

Section: Introductionmentioning

confidence: 99%

“…8-hydroxyacids have also been detected as shellac components 6 . With regards to the terpenoid acids, the disproportionation products of jalaric and laccijalaric acids are usually detected 8,10,17,18 . In these compounds the original aldehyde group is substituted by a hydroxyl or carboxyl group.…”

Section: Introductionmentioning

confidence: 99%

“…These molecules are produced via a Cannizzaro-type reaction, which occurs in alkaline conditions, i.e . during the saponification step usually needed to cleave the ester bonds for subsequent analysis of the resin by GC-MS 8 . However, shellolic and laccishellolic acids are also original components of the resin 17 , produced to a lesser extent by the natural oxidation of aldehyde moieties with ageing.…”

Section: Introductionmentioning

confidence: 99%

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The characterisation of shellac resin by flow injection and liquid chromatography coupled with electrospray ionisation and mass spectrometry

Tamburini

Dyer

Bonaduce

2017

Sci Rep

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A strategy based on electrospray ionisation (ESI) in negative mode coupled with quadrupole-time of flight (Q-ToF) detection techniques was adopted to characterise some samples of shellac resin. Flow injection analysis (FIA) was used to investigate the distribution of the components of the resin. Eight groups of compounds with increasing masses were detected and assigned to free acids, esters and polyesters with up to eight units. High pressure liquid chromatography (HPLC) enabled the compounds to be chromatographically separated. Accurate molecular masses and tandem mass (MS/MS) spectra interpretation were used to characterise the different compounds, assigning and/or suggesting molecular structures. In some cases, highly detailed information about the ester linkages was provided by the MS/MS spectra, enabling the different isomers to be distinguished. Oxidation products were also identified in the samples and differences were observed in terms of hydrolysis and oxidation. In addition to providing the first characterisation of shellac by HPLC-ESI-Q-ToF and an atlas of MS/MS spectra of shellac components, this work demonstrates the suitability of the proposed strategy for characterising the resin, and provides the identification of previously unknown degradation products and minor components. This represents a significant step forward in the chemical knowledge of this material.

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Aliphatic Polyesters

2002

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Introduction Historical Outline Chemical Structure Naturally Occurring Polyesters: Shellac Microbial Polyesters Condensation Polyesters Polyesters Prepared by ROP Structural Modification by Copolymerization Occurrence Degradation Applications Outlook and Perspectives Acknowledgements

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Chemistry of lac resin—I

Cited by 40 publications

References 23 publications

Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks

Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks

The characterisation of shellac resin by flow injection and liquid chromatography coupled with electrospray ionisation and mass spectrometry

Aliphatic Polyesters

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